NREL is a national laboratory of the U.S. Department of Energy, 

Office of Energy Efficiency & Renewable Energy, operated by the 

Alliance for Sustainable Energy, LLC.

Contract No. DE-AC36-08GO28308

National Renewable Energy Laboratory

15013 Denver West Parkway

Golden, CO 80401

303-275-3000 • www.nrel.gov

Case Studies of Potential 

Facility-Scale and Utility-Scale 

Non-Hydro Renewable Energy 

Projects across Reclamation

S. Haase, K. Burman, D. Dahle, D. Heimiller,

A. Jimenez, J. Melius, B. Stoltenberg, and

O. VanGeet

Technical Report

TP-7A30-57123 

May 2013

Produced under direction of Bureau of Reclamation by the National 

Renewable Energy Laboratory (NREL) under Interagency Agreement 

IAG-11-1816 and Task No WFJ2.1000.

Placement for optional 
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy 

Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Contract No. DE-AC36-08GO28308

National Renewable Energy Laboratory

15013 Denver West Parkway

Golden, CO 80401

303-275-3000 • www.nrel.gov

Case Studies of Potential 

Facility-Scale and Utility-Scale 

Non-Hydro Renewable Energy 

Projects across Reclamation 

S. Haase, K. Burman, D. Dahle, D. Heimiller, 

J. Melius, T. Jimenez, B. Stoltenberg, and 

O. VanGeet

Prepared under Task No. WFJ2.1000

Technical Report

TP-7A30-57123 

May 2013
NOTICE

This manuscript has been authored by employees of the Alliance for Sustainable Energy, LLC (“Alliance”) under 

Contract No. DE-AC36-08GO28308 with the U.S. Department of Energy (“DOE”).

This report was prepared as an account of work sponsored by an agency of the United States government. 

Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, 

express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of 

any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately 

owned rights. Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, 

or favoring by the United States government or any agency thereof. The views and opinions of authors expressed 

herein do not necessarily state or reflect those of the United States government or any agency thereof.

Cover photos courtesy of NREL (NREL 15549 and NREL 16706) 

Printed on paper containing at least 50% wastepaper, including 10% post consumer waste. 
 

iv

Contacts

Bureau of Reclamation National Renewable Energy Laboratory

Curt Brown, Ph.D.

Director, Research and Development

U.S. Bureau of Reclamation 

P.O. Box 25007 

Denver, CO 80225 

303-445-2098

Kari Burman

Senior Engineer 

303-384-7558 

Email: kari.burman@nrel.gov

Erin Foraker 

Renewable Energy Research Coordinator 

Research and Development Office

303-445-3635 

Douglas Dahle 

Principal Program Manager

303-384-7513 

Email: douglas.dahle@nrel.gov

Mitch Haws

Program Development 

Phoenix Area Office

623-773-6274 

Scott Haase

Program Manager, Department of the Interior 

303-275-3057 

Email: scott.haase@nrel.gov

Miguel Rocha

Science and Technology Administrator

Research and Development Office

303-445-2841 

Donna Heimiller

Senior GIS Analyst

303-275-4667 

Email: donna.heimiller@nrel.gov

Diana Weigmann, Ph.D.

Sustainability/Energy Coordinator 

Policy and Administration (Policy)

303-445-2940 

Tony Jimenez

Senior Engineer 

303-384-7027 

Email: tony.jimenez@nrel.gov 

Blaise Stoltenberg

Senior Engineer 

303-384-6833 

Email: blaise.stoltenberg@nrel.gov 

Otto VanGeet, P.E.

Senior Mechanical Engineer 

303-384-7369 

E-mail: otto.vangeet@nrel.gov
 

v 

Acknowledgments

The National Renewable Energy Laboratory (NREL) thanks the Bureau of Reclamation for 

funding this work. In particular, NREL is grateful to Dr. Curt Brown, Miguel Rocha, and Erin 

Foraker for their leadership and assistance with the overall work. 

Additional thanks to: 

• Mitch Haws, Aaron Adam Ricks, and Don Reiff for their initial GIS analysis of the 

Central Arizona Project, and to Mitch Haws, Don Reiff, Mike Pryor, and David Trimm

for hosting the NREL team during the site visit in August 2011. 

• Diana Weigmann for her insights into Reclamation’s sustainability program and efforts to 

integrate renewable into existing facilities. 

• Bruce Whitesell for providing utility-scale Reclamation data layers.
 

vi 

List of Abbreviations and Acronyms

AC alternating current

ACC Arizona Corporation Commission 

APS Arizona Public Service

BLM U.S. Department of the Interior, Bureau of Land Management 

CAISO California independent system operator 

CAP Central Arizona Project

CPUC California Public Utilities Commission

CPV concentrating photovoltaics 

CSI California solar incentives

CSP concentrating solar power 

DC direct current

DG distributed generation

DNI direct normal irradiance

DOE U.S. Department of Energy 

DRECP Desert Renewable Energy Conservation Plan

DSCR debt service coverage ratio

DSIRE Database for State Incentives for Renewable Energy

EIS environmental impact statement

ft2 square-foot 

FTHL flat-tailed horned lizard

FY fiscal year

GHG greenhouse gas

GHI global horizontal irradiance

GIS geographic information system 
 

vii 

GSA U.S. General Services Administration 

IEEE Institute of Electrical and Electronics Engineers

IRR internal rate of return

ITC investment tax credit

km2 square-kilometer

kV kilovolt 

kW kilowatt 

kWh kilowatt-hour 

lbs pounds 

LCOE levelized cost of energy

LEED Leadership in Energy and Environmental Design 

m

2 square-meter

MA management area

MACRS modified accelerated cost-recovery system

MW megawatt

MWh megawatt-hour 

NEPA National Environmental Policy Act

NEG net excess generation

NGS Navajo Generating Station 

NREL National Renewable Energy Laboratory 

O&M operation and maintenance 

PBI performance-based incentives

PG&E Pacific Gas and Electric

PPA power purchase agreement

PV photovoltaics 
 

viii

RE renewable energy

REC renewable energy certificate 

Reclamation U.S. Department of the Interior, Bureau of Reclamation 

ROW right-of-way

RPS renewable portfolio standard

RPUID real property unique identifier 

SDGE San Diego Gas & Electric

SEZ solar energy zone

SHPO State Historic Preservation Office

SROPTTC Site, Resource, Offtaker, Permits, Technology, Team, and Capital 

SRP Salt River Project (electric utility)

TMY typical meteorological year

TOU time of use 

USFWS U.S. Fish & Wildlife Service

W watt

WAPA Western Area Power Administration
ix

Table of Contents

List of Abbreviations and Acronyms ....................................................................................................... vi

List of Figures ........................................................................................................................................... xii

List of Tables ............................................................................................................................................ xiv

Executive Summary.................................................................................................................................. xv

1 Background ........................................................................................................................................... 1

2 Solar Technology Overview ................................................................................................................ 3

2.1 Introduction...................................................................................................................................... 3

2.2 Solar Thermal (Concentrating Solar Power) Technologies............................................................. 3

2.2.1 Parabolic Trough............................................................................................................... 3

2.2.2 Power Tower..................................................................................................................... 6

2.2.3 Dish Stirling ...................................................................................................................... 7

2.3 Photovoltaic Technologies............................................................................................................... 9

2.3.1 How Solar Cells Work ...................................................................................................... 9

2.3.2 PV System Components.................................................................................................... 9

2.3.3 Facility-Scale PV ............................................................................................................ 10

2.3.4 Utility-Scale PV.............................................................................................................. 11

2.4 Government Incentives for Solar Energy Plants............................................................................ 13

2.4.1 Federal and States Incentives.......................................................................................... 13

3 Wind Technology Overview............................................................................................................... 15

3.1 Introduction.................................................................................................................................... 15

3.2 How Wind Turbines Work............................................................................................................. 15

3.2.1 Wind Turbine Topologies............................................................................................... 15

3.2.2 Wind Turbine Components............................................................................................. 16

3.2.3 Wind Turbine Siting........................................................................................................ 17

3.3 Wind Turbine Market and Applications........................................................................................ 18

3.3.1 Introduction..................................................................................................................... 18

3.3.2 Small Wind Turbines...................................................................................................... 18

3.3.3 Large Wind Turbines...................................................................................................... 20

3.3.4 Mid-Size Wind Turbines................................................................................................. 21

3.4 Government Incentives for Wind Energy Projects........................................................................ 22

3.4.1 Federal Incentives........................................................................................................... 22

4 GIS Screening ..................................................................................................................................... 23

4.1 Utility-Scale Screening .................................................................................................................. 23

4.1.1 Concentrating Solar Power ............................................................................................. 23

4.1.2 Utility-Scale Photovoltaics ............................................................................................. 23

4.1.3 Onshore Wind ................................................................................................................. 24

4.2 Results............................................................................................................................................ 24

4.3 Facility-Scale Screening ................................................................................................................ 28

5 Facility-Scale Assessment of Phoenix Area Office ........................................................................ 31

5.1 Energy Use and Utility Data .......................................................................................................... 32

5.2 Facility-Scale PV Systems............................................................................................................. 34

5.3 PV Site Location and Performance................................................................................................ 34

5.4 Potential Roof and Carport Areas.................................................................................................. 36

5.5 Economics and Performance.......................................................................................................... 40

5.5.1 Assumptions and Input Data for Analysis ...................................................................... 40

5.5.2 Other Incentives and Financing Opportunities................................................................ 41

5.5.3 Data and Assumptions .................................................................................................... 43

5.5.4 Performance and Savings Results................................................................................... 43

5.6 Facility-Scale Conclusions and Recommendations....................................................................... 45

6 Facility-Scale Assessments of Willows Office and Lake Berryessa Facility ............................... 46
x 

6.1 Willows Office ................................................................................ .............................................. 46

6.1.1 Willows Office—Facility Overview............................................................................... 46

6.1.2 Willows Office—PV Performance ................................................................................. 48

6.1.3 Willows Office—Potential PV System Locations.......................................................... 50

6.2 Lake Berryessa Office.................................................................................................................... 52

6.2.1 Lake Berryessa Office—Facility Overview.................................................................... 52

6.2.2 Lake Berryessa—PV Performance ................................................................................. 54

6.2.3 Lake Berryessa Office—Potential PV System Locations............................................... 55

6.3 Facility-Scale PV Systems............................................................................................................. 57

6.4 Economics and Performance.......................................................................................................... 57

6.4.1 Assumptions and Input Data for Analysis ...................................................................... 57

6.4.2 Other Incentives and Financing Opportunities................................................................ 58

6.4.3 Data and Assumptions .................................................................................................... 59

6.4.4 Performance and Savings Results................................................................................... 59

6.5 Facility-Scale Conclusions and Recommendations....................................................................... 62

7 Utility-Scale Assessment of Pumping Plants Along the Central Arizona Project ....................... 63

7.1 Site Assessments............................................................................................................................ 63

7.2 PV Potential to Meet Hassayampa Pumping Load ........................................................................ 66

7.2.1 Electrical Production Analysis........................................................................................ 66

7.2.2 Economics....................................................................................................................... 68

7.3 Technology Description................................................................................................................. 69

7.4 Preliminary Solar Plant Economics............................................................................................... 70

7.4.1 Federal and States Incentives.......................................................................................... 70

7.5 Modeling Preliminary Economic Feasibility ................................................................................. 70

7.6 Large-Scale Solar Project Development Issues............................................................................. 71

7.7 Utility-Scale Analysis—Next Steps............................................................................................... 73

8 Yuma Utility-Scale Solar Assessment.............................................................................................. 74

8.1 Introduction.................................................................................................................................... 74

8.2 Site Descriptions............................................................................................................................ 74

8.2.1 Brock Reservoir .............................................................................................................. 75

8.2.2 Site A22 .......................................................................................................................... 77

8.3 Solar Resource ............................................................................................................................... 78

8.4 Transmission Access...................................................................................................................... 82

8.5 Analysis Assumptions.................................................................................................................... 82

8.6 Analysis.......................................................................................................................................... 84

8.7 Next Steps....................................................................................................................................... 85

9 Utility-Scale Wind Assessment of North Platte Cluster..................................................................... 88

9.1 Introduction .................................................................................................................................... 88

9.2 Reclamation Land Description....................................................................................................... 90

9.3 Suitablity Assessment..................................................................................................................... 91

9.3.1 Wind Resource.................................................................................................................. 91

9.3.2 Available Land/Road Access/Constructability ................................................................ 93

9.3.3 Transmission Access........................................................................................................ 94

9.3.4 Environmental.................................................................................................................. 95

9.3.5 Community Receptiveness.............................................................................................. 95

9.4 Ownership Structures..................................................................................................................... 95

9.5 Economic Analysis......................................................................................................................... 96

9.6 Results Discussion........................................................................................................................ 100

9.7 Overall Conclusions and Recommendations................................................................................ 103

10 Montana Reclamation Lands Wind Screening Assessment........................................................ 104

10.1 Introduction ........................................................................................................................... 104
 

xi 

10.2 Methodology ......................................................................................................................... 104

10.3 Sites Summary....................................................................................................................... 105

10.4 General Notes, Conclusions, and Next Steps........................................................................ 106
 

xii 

List of Figures

Figure 2-1. Parabolic troughs are aligned north-south and track the sun from east to west............. 4

Figure 2-2. Schematic of a CSP thermal electric plant that can also use thermal storage ................. 4

Figure 2-3. 280 MW Arizona trough plant. ................................................................................................ 5

Figure 2-4. Aerial view of CSP trough plants at Kramer Junction, California (in operation for 30 

years) ..................................................................................................................................................... 5

Figure 2-5. Solar trough at a 50 MW plant ................................................................................................ 6

Figure 2-6. DOE solar demonstration power tower in southern Nevada .............................................. 7

Figure 2-7. Aerial view of Daggett, California, DOE solar demonstration power tower. .................... 7

Figure 2-8. Characteristics of a CSP dish engine system ...................................................................... 8

Figure 2-9. 1.5-MW Maricopa, Arizona, solar power plant–60 25-kW dish Stirling systems ............... 8

Figure 2-10. Generation of electricity from a PV cell............................................................................... 9

Figure 2-11. Depiction of major components of grid-connected PV systems.................................... 11

Figure 2-12. Ground mount array diagram............................................................................................. 12

Figure 2-13. 8 MW, single-axis tilt-PV system in Alamosa, Colorado.................................................. 13

Figure 2-14. Photovoltaic field at the National Wind Technology Center ........................................... 13

Figure 3-1. Large wind turbine components .......................................................................................... 17

Figure 3-2. Wind turbine siting ................................................................................................................ 18

Figure 3-3. Basic parts of a small wind turbine ..................................................................................... 19

Figure 3-4. Examples of small wind turbines......................................................................................... 19

Figure 3-5. Wind farm schematic............................................................................................................. 20

Figure 3-6. Large wind turbines............................................................................................................... 21

Figure 3-7. Mid-size wind turbine ............................................................................................................ 22

Figure 5-1. Aerial view of Phoenix Area Office ...................................................................................... 31

Figure 5-2. Phoenix Area Office south elevation view .......................................................................... 32

Figure 5-3. Electrical cost (FY06 – FY11)................................................................................................ 33

Figure 5-4. Electrical usage (kWh, FY06 – FY11)a.................................................................................. 33

Figure 5-5. Proposed PV system locations for Reclamation’s Phoenix building............................... 35

Figure 5-6. Typical ballasted PV system at GSA Denver Federal Center (Phoenix Area Office 

building roof PV would be similar) ................................................................................................... 36

Figure 5-7. South wing looking west where PV is proposed (left) and looking south (right) ........... 36

Figure 5-8. East wing roof looking east is also suitable for PV (left) and typical parapet is 

approximately 28” high (right) .......................................................................................................... 37

Figure 5-9. Panel LP2A has many spaces where a PV breaker could be installed (left) and 225 

ampere (A) 480 V Panel LP2A has adequate capacity for PV (right) ............................................. 37

Figure 5-10. Panel LP2A is located in the electrical room near the roof............................................. 37

Figure 5-11. Existing carports looking southeast (left) and looking northeast (note existing PV on 

east-most carports) (right) ................................................................................................................. 38

Figure 5-12. Northwest carports looking northwest (left) and carport structure, which would 

require the attachment of PV support racking (right)..................................................................... 38

Figure 5-13. Solmetric SunEye used to measure solar access (all recommended areas have 

excellent solar access) ...................................................................................................................... 39

Figure 5-14. Possible CPV location behind center light post (which would need to be removed) 

(left) and close up of area (right)....................................................................................................... 40

Figure 5-15. Possible CPV locations at southwest corner of site (left) and behind southeast 

sidewalk (right). .................................................................................................................................. 40

Figure 5-16. PV costs................................................................................................................................ 41

Figure 6-1. Aerial view of Willows Office................................................................................................ 47

Figure 6-2. Willows Office entrance and north elevation view (left), and Willows Office northeast 

view (right)........................................................................................................................................... 47

Figure 6-3. Site plan of Willows Office.................................................................................................... 48

Figure 6-4. Existing inverters and PV system at Willows Office.......................................................... 48

Figure 6-5. Proposed PV system locations at Reclamation’s Willows building (in blue) ................. 49

Figure 6-6. Existing PV system electrical breaker subpanel (left) and right building main 240 V, 600 

A electrical panel with spaces for future solar breakers................................................................ 50
xiii

Figure 6-7. East roof of Willow building looking north (Area 1) (left), and east side of building and 

roof looking northwest (right) ........................................................................................................... 51

Figure 6-8. South-facing courtyard roof of Willow building looking west (Area 2) (left) and southfacing courtyard roof looking north from courtyard (right) ........................................................... 51

Figure 6-9. PV-covered carports could be installed over parking lot: (clockwise from upper left) 

looking northeast, looking east, east edge looking north (notice shade from trees defines east 

boundary), and looking southeast.................................................................................................... 52

Figure 6-10. Aerial view of Lake Berryessa Office................................................................................. 53

Figure 6-11. Existing PV system and inverters at Lake Berryessa Office (existing PV 1)................. 53

Figure 6-12. Second existing PV system and inverters at Lake Berryessa Office (existing PV 2)... 

54 Figure 6-13. Proposed PV system locations at Reclamation’s Lake Berryessa site (highlighted 

in blue) ..................................................................................................................................................... 55

Figure 6-14. PV Area 1 looking west (note existing PV 1 near sidewalk in distance) (left) and east 

side of PV Area 1 looking northeast (right) ..................................................................................... 55

Figure 6-15. PV Area 2 beyond fence looking north (left) and PV Area 3 looking northeast (right). 56

Figure 6-16. PV Carport Area 1: looking southeast (left) and looking north (right)........................... 56

Figure 6-17. PV Carport Area 2: looking northeast (left), and main meter and electrical panel that 

serves south buildings at Lake Berryessa and possible PV tie in location (right) ...................... 56

Figure 6-18. PV costs................................................................................................................................ 58

Figure 7-1. High potential solar site east of Little Harquahala Pumping Station ............................... 63

Figure 7-2. View of site 1 looking north from northern edge of CAP .................................................. 64

Figure 7-3. High potential solar site east of Hassayampa Pumping Station ...................................... 65

Figure 7-4. View looking north at site 3 from northern edge of CAP................................................... 65

Figure 7-5. Annual average daily load profile at Hassayampa............................................................. 66

Figure 7-6. Seasonal load profile for Hassayampa................................................................................ 66

Figure 7-7. Monthly average electric production (100 MW system)..................................................... 67

Figure 7-8. Annual hourly PV production at Hassayampa.................................................................... 68

Figure 7-9. Sensitivity analysis on increase price of power................................................................. 69

Figure 8-1. Proposed solar project locations......................................................................................... 74

Figure 8-2. Proposed solar project locations......................................................................................... 75

Figure 8-3. Proposed Brock Reservoir site (west)................................................................................. 76

Figure 8-4. Proposed Brock Reservoir site (east) ................................................................................. 77

Figure 8-5. Proposed A22 site.................................................................................................................. 78

Figure 8-6. California global at latitude tilt solar resource (PV)........................................................... 79

Figure 8-7. Arizona global at latitude tilt solar resource (PV) .............................................................. 80

Figure 8-8. Arizona concentrating solar resource (CPV and CSP) ...................................................... 81

Figure 8-9. DRECP starting point map.................................................................................................... 86

Figure 8-10. DRECP alternative 5 map.................................................................................................... 87

Figure 9-1. Reclamation North Platte cluster......................................................................................... 88

Figure 9-2. Reclamation North Platte cluster......................................................................................... 89

Figure 9-3. Relief map of the North Platte cluster.................................................................................. 90

Figure 9-4. Reclamation North Platte cluster wind resource................................................................ 91

Figure 9-5. Morgan Creek area and northern Seminoe Reservoir wind resource (close up of Figure 

9-4) ....................................................................................................................................................... 92

Figure 9-6. North Platte cluster wind rose.............................................................................................. 92

Figure 9-7. Morgan Creek area road access........................................................................................... 93

Figure 9-8. Hypothetical turbine layout on Reclamation parcel at northern end of Seminoe 

Reservoir ............................................................................................................................................. 94

Figure 9-9. Sage grouse habitat in the North Platte cluster ................................................................. 95

Figure 9-10. Wind farm location on 80 m wind map 80 m wind data ................................................... 97

Figure 10-1. Glacier County Reclamation-owned land........................................................................ 110

Figure 10-2. Chouteau County Reclamation-owned land ................................................................... 110

Figure 10-3. Phillips County Reclamation-owned land....................................................................... 111

Figure 10-4. Hill County Reclamation-owned land .............................................................................. 111

Figure 10-5. Teton County Reclamation-owned land.......................................................................... 112

Figure 10-6. Teton and Liberty County Reclamation-Owned Land.................................................... 112
xiv 

List of Tables

Table ES-1. Summary of Specific Tasks and Results .......................................................................... xvi

Table 4-1. Top 20 Counties by CSP Potential Installed Capacity......................................................... 26

Table 4-2. Top 20 Counties by Utility-Scale PV Potential Installed Capacity...................................... 26

Table 4-3. Top 20 Counties by Wind Potential Installed Capacitya ...................................................... 27

Table 4-4. Reclamation Facilities with the Highest Potential Energy Delivered from Solar Vent 

Preheating ........................................................................................................................................... 28

Table 4-5. Reclamation Facilities with the Highest Annual Average Photovoltaic Resource from a 

Fixed Flat-Plate Collector with Tilt Equal to Latitude ..................................................................... 29

Table 4-6. Reclamation Facilities with the Highest Annual Average Wind Resource at 50 m Height 

Above Ground..................................................................................................................................... 29

Table 5-1. Annual AC Energy and Cost Savings Results in kWh/kW for 10-Degree Fixed-Tilt PV 

from PVWatts for Phoenix ................................................................................................................. 35

Table 5-2. PV Economics–Phoenix Area Office ..................................................................................... 44

Table 6-1. Annual AC Energy and Cost Savings Results in kWh/kW for South-Facing, 5-DegreeSloping, Fixed-Tilt PV from PVWatts for Willows (Carport PV) ..................................................... 49

Table 6-2. Annual AC Energy and Cost Savings Results in kWh/kW for South-Facing, 5-Degree, 

Fixed-Tilt PV from PVWatts for Lake Berryessa.............................................................................. 54

Table 6-3. PV Economics.......................................................................................................................... 61

Table 7-1. Electrical Production .............................................................................................................. 67

Table 7-2. Comparison of Grid Cost with PV Sizes ............................................................................... 68

Table 7-3. Preliminary Economic Feasibility Model Results ................................................................ 71

Table 8-1. Assumptions Used in Analysis.............................................................................................. 83

Table 8-2. Brock Reservoir Analysis Results......................................................................................... 84

Table 8-3. Yuma Desalting Plant Sludge Disposal Site Analysis Results........................................... 84

Table 9-1. Site and Turbine Assumptions .............................................................................................. 98

Table 9-2. Economic and Financial Assumptions ................................................................................. 99

Table 9-3. Analysis Results–Cash Purchase Option........................................................................... 101

Table 9-4. Analysis Results–Third-Party Lease ................................................................................... 102

Table 10-1. High-Level Wind Energy Potential Assessment for BOR Land in Montana (Part 1)a... 107

Table 10-2. High-Level Wind Energy Potential Assessment for BOR Land in Montana (Part 2) .... 108

Table 10-3. High-Level Wind Assessment for BOR Land in Montana (Part 3)a ................................ 109
xv 

Executive Summary

The following report summarizes the results of an assessment and analysis of renewable energy

opportunities conducted for the U.S. Department of the Interior, Bureau of Reclamation 

(Reclamation) by the National Renewable Energy Laboratory (NREL). The work was conducted 

under interagency agreement number IAG-11-1816, entitled Technical Assistance for the Bureau

of Reclamation’s Non-Hydro Renewable Energy Program. This report represents the results of

Tasks 1.1 and 1.2 of the effort (Resource Screening and Site Assessments).

In particular, this report contains results from the following tasks and activities:

Task 1.1–GIS Utility-Scale Screening. Using geographic information system (GIS) technology, 

identify and rank Reclamation lands potentially suitable for wind and solar energy development. 

This publication gives only a summary of the results. Full results are given in the publication 

“Renewable Energy Assessment of Bureau of Reclamation Land and Facilities Using

Geographic Information Systems.”1

Task 1.1.1–Utility-Scale Site Visits. Conduct detailed technical and economic assessments of

Reclamation lands potentially suitable for development. This report includes solar assessments of

a site along the Central Arizona Project (CAP), solar assessments for two sites near Yuma, AZ,

and a wind energy development assessment for the North Platte cluster in Wyoming. 

Task 1.1.1–Montana Screening Analysis. Conduct a screening analysis of Reclamation-owned 

property in Montana to identify the parcels most suitable for wind energy development. 

Task 1.2–GIS Facility-Scale Screening. Using GIS, identify Reclamation facilities that have

the best potential for deployment of facility-scale wind and/or solar energy resources. This

publication gives only a summary of the results. Full results are given in the publication 

“Renewable Energy Assessment of Bureau of Reclamation Land and Facilities Using

Geographic Information Systems.” 

Task 1.2.1–Facility-Scale Site Visits. Conduct an analysis of the technical and economic 

feasibility of installing solar energy technologies at Reclamation’s Phoenix Area Office and the 

Willows and Lake Berryessa (California) offices. 

1 Haase, et al. Renewable Energy Assessment of Bureau of Reclamation Land and Facilities Using Geographic 

Information Systems (forthcoming). NREL/TP-7A30-57123. Golden, CO: National Renewable Energy Laboratory.
 

xvi 

Summary Results

The specific activities completed and key results are highlighted in Table ES-1. 

Table ES-1. Summary of Specific Tasks and Results

Task Description Key Results

Geographic 

Information 

System (GIS) 

Screening 

Utility: Used GIS to identify Reclamationowned land (by county) potentially suitable for 

utility-scale concentrating solar power (CSP),

photovoltaic (PV), and wind power 

development

Facility: Used GIS to analyze 748 

Reclamation facilities’ potential suitability for 

solar vent preheating, PV, and small wind

power

• The counties with the greatest potential for CSP, PV, and wind power 

development on Reclamation lands were identified and ranked from 

highest to lowest. Further analysis is necessary at each individual site to 

identify the specific capacity potential based on Reclamation’s land and 

facilities.

• For each technology, the facilities were ranked in terms of the available 

resource.

Facility-Scale 

Assessment at 

Phoenix Area 

Office

Conducted a technical and economic feasibility 

analysis of installing PV at the Phoenix area 

office

• The facility can host up to 200 kW of PV.

• Salt River Project (SRP) incentives are available for systems up to 30

kW in size.

• The payback for a federal government-owned system (up to 30 kW) is 

estimated to be 27 years. A power purchase agreement (PPA) with a 

private developer may have better economics. Systems larger than 30 

kW in size are currently ineligible for SRP incentives and thus will have 

longer payback periods. 
xvii 

Task Description Key Results

Facility-Scale 

Assessment at

Willows Office

(Mid-Pacific

Construction 

Office) and 

Lake Berryessa

Facility 

Conducted a technical and economic feasibility

analysis of installing PV at the Willows Office 

and Lake Berryessa facility (located in 

California) 

• The Willows Office already has a small PV installation that generates

approximately 12,000 kWh/year.

• The east roof (Area 1) at the Willows Office can accommodate 15 kW of

PV. Estimated payback is 22-25 years for a federal government-owned

system.

• The south courtyard roof at the Willows Office can accommodate up to

20 kW of PV but will require extensive tree trimming or removal.

Estimated payback is 15 years for a third party-owned system or 22

years for a federal government-owned system.

• A carport at the Willows Office could accommodate up to 220 kW of PV

(93 kW is sufficient to make the office net zero). Operational constraints

preclude a carport at this time. Payback is estimated to be 15 years for a

third party-owned system.

• The Lake Berryessa facility has three ground-mounted PV opportunities

totaling 133 kW. Estimated payback is 15 years for a third party-owned

system and 22 years for a federal government-owned system.

• The Lake Berryessa facility has two potential carport-mounted PV

opportunities. Estimated payback is 16 years for a third party-owned

system and 24 years for a federal government-owned system.

Operational considerations preclude carports in some locations at this

time. 
 

xviii 

Task Description Key Results

Utility-Scale 

Assessment of 

Pumping Along

the Central 

Arizona Project

(CAP) 

Conducted site assessments of three potential 

sites for utility-scale CSP and PV facilities: 

• East of Little Harquahala Pumping Station 

(La Paz and Maricopa Counties) 

• Belmont Mountain

• East of Hassayampa Pumping Station

• The location east of the Hassayampa Pumping plant determined to be 

the most viable site.

• Most cost-effective option is a 20-100 MW third party-owned, single-axis 

tracking PV plant. The levelized cost of energy (LCOE) is estimated at 

$0.10/kWh.

• LCOE of comparable CSP plant is approximately $0.17/kWh. 

• The analysis used publicly available capital cost data. Informal 

discussions with developers indicate that current capital costs are lower 

than those used in the analysis. Thus the actual LCOEs are likely to be 

less than shown in the analysis. Recent PPA prices for solar projects 

appear to be in the $0.07-$0.10/kWh range. In terms of costs of energy, 

this site appears to be competitive for a PV project.

• Near-term demand for PV project is uncertain. Many utilities have met 

their near- and mid-term solar renewable portfolio standards (RPS)

obligations. Despite dropping costs for PV power plants, LCOEs from PV 

plants are higher than current LCOEs from natural gas-fired power 

plants due to current low natural gas prices.

Utility-Scale 

Solar 

Assessment at 

Yuma

Conducted site assessments of two sites for 

utility-scale CSP, power tower, and PV 

facilities: 

• Brock Reservoir

• A22

• Shape of the Brock Reservoir parcel precludes CSP or power tower 

facilities. Estimated LCOE for PV is approximately $0.10/kWh.

• For A22, the most cost-effective option is PV, with an LCOE of 

approximately $0.10/kWh. Power tower is a close second choice with an 

LCOE of approximately $0.11/kWh. 

• The analysis used publicly available capital cost data. Informal 

discussions with developers indicate that current capital costs are lower 

than those used in the analysis. Thus the actual LCOEs are likely to be 

less than shown in the analysis. Recent PPA prices for solar projects 

appear to be in the $0.07-$0.10/kWh range. In terms of costs of energy, 

this site appears to be competitive for PV and perhaps power tower 

projects.

• Near-term demand for PV project is uncertain. Many utilities have met 

their near- and mid-term solar RPS obligations. Despite dropping costs 

for PV power plants, the LCOEs from PV power plants are higher than 

current LCOEs from natural gas-fired power plants due to current low 

natural gas prices.
 

xix 

Task Description Key Results

Utility-Scale Wind 

Assessment of 

North Platte 

Cluster

Evaluated the North Platte cluster, a set of 

Reclamation-owned parcels along the North 

Platte River west of Casper, Wyoming, for 

suitability for wind energy development

• Compared with neighboring land, the Reclamation-owned parcels within 

the North Platte cluster do not appear especially attractive for wind 

energy development. The Reclamation-owned parcels in this area are 

generally of relatively small size (which limits wind farm size unless the 

wind farm extends into non-Reclamation land), awkwardly shaped 

(which leads to inefficient turbine layout), and either in low-lying terrain 

(which generally has less of a wind resource) and/or is comprised of 

rugged terrain (which increases the cost of construction and 

transmission).

• Estimated LCOEs (busbar) for a small, utility-scale wind energy project 

(approximately 10 MW) are $0.07-$0.08/kWh for federal government

owned projects and $0.08-$0.10/kWh for privately owned projects. 

These LCOEs are higher than the current PPA price range of $0.04-

$0.06 per kWh for non-California, non-“Wind Belt” wind farms.

Montana Wind 

Screening 

Analysis

Conducted a screening analysis of 

Reclamation-owned property in Montana to 

identify the parcels most suitable for wind 

energy development

• Identified one set of parcels, (Chouteau County cluster), that can support 

over 300 MW of wind energy development, and two parcels (Glacier 

County cluster, Philips County cluster) that can support approximately

100 MW each. 

• Identified five additional parcels that can potentially support modest (50-

100 MW) wind energy development.

• Selected Reclamation-owned parcels appear to have development 

potential; however, in general, Reclamation-owned parcels do not 

appear to offer compelling advantages over nearby non-Reclamationowned land. In most cases, Reclamation-owned parcels will need to be 

aggregated with adjacent non-Reclamation-owned land to support a 

large wind farm.
xx 

Conclusions

Facility-Scale Renewables 

Reclamation’s Phoenix Area Office, Willows Construction Office, and Lake Berryessa Office 

each have near-ideal areas in which to implement a PV system. However, the Willows 

Construction Office and Lake Berryessa Office both have operational considerations that 

preclude implementation for some of the identified carport areas at this time. The remaining 

potential project at Willows is less cost-effective, but may still merit consideration. 

If Reclamation chooses to proceed with this type of installation at the Phoenix office, it should 

contact Salt River Project (SRP) and reserve incentives for a 30 kW direct current (DC) system

(or other size, as determined by Reclamation). If incentives for larger systems become available 

again, a larger system should be installed. Similarly, if Reclamation chooses to proceed with 

these installations at Willows and/or Lake Berryessa, Reclamation should reserve incentives 

with Pacific Gas and Electric Company (PG&E). 

When the systems go out to bid, a design-build contract should be issued that requests the best 

performance (in kWh/yr) at the best price, letting the vendors optimize the system configuration, 

including racking, slope, modules, etc. Because of the high cost of energy, the dropping cost of 

PV, the excellent solar resource, and excellent incentives, government-owned PV systems 

provide reasonable payback, are easy to implement, and are therefore recommended. 

If funding is not available, then a third-party PPA is the most reasonable way for a system to be

financed at these sites. Due to high transaction costs, third-party ownership of PV systems sited

at government facilities is generally only feasible for systems larger than 90-100 kW or so. A

possible method to install smaller (< 90 kW) systems under a third-party ownership scenario 

would be to aggregate the installation of PV systems at several facilities under one contract. 

More generally, Reclamation should consider a program to systematically screen and assess 

Reclamation-owned facilities for suitability for renewable energy projects. The recently

completed facility GIS screening is a key step in this process. This would be followed by RE 

installations at those facilities found to be most suitable. It is anticipated that solar PV will be 

generally suitable, but opportunities to deploy other technologies such as solar preheating, small

wind, and geothermal may exist. When evaluating facility-scale RE projects, consideration 

should be given to EISA Sec 434, which mandates a 40-year analysis period when conducting 

life cycle cost (LCC) analysis of major equipment replacement, expansion, renovation, etc. 

Utility-Scale Solar

Given current power market conditions and the low costs of power from the Navajo Generating 

Station (NGS), the economic case of installing utility-scale solar on Reclamation land and using 

this power directly to power Central Arizona Project (CAP) pumps is challenging on a cost basis. 

However, given the continued drop in solar prices and an expected increase in NGS generation 

costs over time, it will be important for Reclamation to monitor market conditions going forward 

and revisit this analysis as situations change.

Evaluation of the Brock Reservoir and A22 sites indicates that these sites are potentially suitable 

for utility scale solar projects. Of the available solar technologies, single axis PV appears to be
xxi 

the most cost-effective, with a levelized cost of energy (LCOE) of $0.10-$0.11 per kWh using 

published installation cost data. Informal discussions with developers and more recent data 

indicate that installation costs have continued to drop. Using these costs would likely result in 

LCOEs of $0.08-$0.10 per kWh for PV projects, which is comparable to the most recent PPA 

prices.

If Reclamation desires to pursue siting of utility-scale projects on its land, the best case would be 

for Reclamation to act simply as a land owner and issue a right-of-way grant to a private sector 

company. Results of the analysis in this report indicate that the developer would need to obtain a 

long-term PPA from a utility of at least $0.10/kWh (perhaps lower if more recent installation 

costs are used) to make the project economically viable. The ability of a private sector company 

to obtain a purchase price of $0.10/kWh is not known at this time. The demand for renewable 

energy in the western United States is dependent on a number of factors, including regulatory 

mandates arising from state renewable portfolio standards (RPSs), low prices for natural gas, 

lack of transmission into the California market, and projections for continued drops in PV prices 

due to technology improvements and structural imbalances (global oversupply of panel 

manufacturing capacity) in the industry. Many utilities have met their near- and mid-term solar 

RPS requirements. Currently, due to low natural gas prices, the LCOEs of natural gas power 

plants are lower than for PV plants, which may limit utility appetite for PV plants in the short 

term.

One next step to further facilitate siting a project on Reclamation land would be for Reclamation 

to prequalify the development potential of the most promising sites (e.g., Hassayampa, Brock 

Reservoir, and A22), especially in terms of identifying areas that are near transmission lines that 

have the capacity and the potential for very low environmental and cultural impacts. The Bureau 

of Land Management (BLM) is conducting an analysis in Arizona called the Restoration Design 

Project to identify the best suitable lands and areas in the state for renewable energy 

development. Reclamation’s Phoenix Area Office has submitted the top five sites identified in its 

“Renewable Energy Suitability Analysis for the Central Arizona Project Canal System” to the 

BLM for inclusion in the Restoration Design Energy Project Environmental Impact Statement 

(EIS). Alternatively, Reclamation could conduct its own programmatic EIS or a site-specific EIS 

for a given site. Once Reclamation determines that a site is a high quality location with strong 

development potential, Reclamation can issue a competitive lease solicitation that can be used to 

evaluate industry interest in moving forward with a project at that site. 

Utility-Scale Wind

In general, Reclamation-owned parcels are not strong candidates for utility-scale wind energy 

development. Due to its mission, Reclamation-owned parcels tend to be relatively small

compared to the area needed for a wind farm. In addition, most Reclamation-owned land is 

generally located near water, which being at a comparatively lower elevation, has a weaker wind 

resource than nearby areas. Finally, many Reclamation-owned parcels are awkwardly shaped, 

precluding efficient turbine array layout. For these reasons, Reclamation-owned land is, in 

general, less attractive for wind energy development than nearby privately owned or BLM land. 

While most Reclamation-owned parcels may not be suitable for hosting whole wind farms, some 

parcels may be suitable to host portions of wind farms that are mainly sited on adjacent land. 

Reclamation-owned parcels are often located near larger parcels of BLM-owned land. By 
xxii 

harmonizing its procedures with BLM, Reclamation may encourage developers to expand

projects onto Reclamation-owned land. 

Next Steps

Utility-Scale GIS Screening

As appropriate, NREL can work with Reclamation to improve the level of detail associated with 

the GIS screening. One possible next step is to replace the “land areas of interest” with the actual

size and location of Reclamation-owned parcels. This will allow for more accurate estimates of

the solar and wind energy potential of Reclamation-owned parcels. Follow-on analysis may also

include consideration of regional wholesale electricity prices and regional demand for utilityscale RE facilities.

Facility-Scale GIS Screening

As appropriate, NREL can work with Reclamation staff to improve the level of detail associated

with the facility-level GIS screening. A potential next step would be to redo the analysis taking 

into consideration the cost of electricity at each facility, as well as potential incentives available 

at each location. In addition to the available renewable energy resource, the cost of electricity

greatly impacts the economics of facility-scale renewable energy projects. 

Identify additional candidate sites to perform more detailed facility-scale site visits and 

evaluations similar to what was done for the Phoenix Area Office, Willows Office, and Lake 

Berryessa facility. 

Facility-Scale Site Visit for Phoenix Area Office Photovoltaics and Willows/Lake 

Berryessa Photovoltaics 

Should Reclamation decide to further pursue facility-scale solar at the Phoenix, Willows, or 

Lake Berryessa sites, the following steps should be undertaken (as desired by Reclamation, 

NREL can assist with any or all of these steps): 

• Determine the preferred ownership models (government ownership or third-party

ownership)

• Determine if PV should be installed at other Reclamation-owned facilities in the region (a

larger aggregate purchase may allow for lower unit costs)

• If there is interest in third-party ownership, contact developers to determine interest in a

PPA model for the various options at each site

• Procure the system (procurement, bid evaluation, design reviews, etc.).

Utility-Scale Site Development for Hassayampa, Brock Reservoir, or A22 

Should Reclamation decide to further pursue utility-scale solar at the Hassayampa, Brock 

Reservoir, or A22 sites, the following steps, comprising an initial project development roadmap, 

should be undertaken: 

• Contact transmission line owners, CAP, and the Western Area Power Administration to

determine the technical feasibility of interconnecting PV at Hassayampa
xxiii 

• Conduct a fatal flaw analysis for the presence of any significant cultural and 

environmental concerns at the site

• If transmission access is favorable, then: 

o Brief key Reclamation decision-makers on the potential for large-scale solar 

project development on Reclamation lands

o Identify other stakeholders impacted by project development 

o Prepare a detailed action plan with milestones for project development.

Montana Wind-Screening Analysis

If Reclamation desires a more in-depth evaluation of the top two or three clusters identified in 

this analysis (such as Chouteau, Glacier, or Philips) NREL can assist with this process. 

Utility-Scale Site Development at Other Reclamation Sites 

New environmental regulations are likely to impact the costs of power generation at the NGS. 

These new regulations include the Environmental Protection Agency’s Best Available Retrofit 

Technology rule for NGS, and the utility Maximum Achievable Control Technology rule. While 

the exact impacts of these rules cannot be determined at this time, they are likely to increase the 

costs of generation from NGS. Combined with the expected continued decline of PV prices in 

the coming years, this means that the economics of utility-scale solar at CAP pumping plants are 

likely to improve over the next several years. Reclamation should continue to monitor these 

issues for future evaluation. 

Should Reclamation decide on further work in this area, NREL recommends the following next 

steps:

• Evaluate load profiles at other CAP pumping plants to determine if there are additional 

locations that may be suitable for PV deployment 

• Determine whether there are opportunities to use PV to offset CAP’s use of energy from 

NGS energy during peak periods, thus increasing potential sales of excess NGS energy 

during these periods 

• Work with Reclamation staff to identify additional sites for more detailed utility-scale 

analysis.
1 

1 Background

The President’s National Energy Policy of 2001 and Section 211 of the Energy Policy Act of 

2005 (P.L. 109-58) encourage the development of renewable energy resources, including solar 

and wind energy, as part of an overall strategy to develop a diverse portfolio of domestic energy 

supplies for the future. A partial listing of laws, executive orders, and polices promoting use of 

renewable energy by federal agencies includes:

• Energy Policy Act of 2005 (Public Law 109-58), which addresses energy savings, energy 

management requirements, and energy use accountability

• The Energy Independence and Security Act of 2007 features goals that include increasing 

the production of clean renewable fuels, increasing the efficiency of products, buildings 

and vehicles, and improving the energy performance of the federal government 

• The Omnibus Public Land Management Act of 2009 (Public Law 111-11, Title IX 

Bureau of Reclamation Authorizations, Subtitle F–Secure Water) authorizes grants to 

enhance water management, including increasing the use of renewable energy in the 

management and delivery of water 

• EO 13423, Strengthening Federal Environmental, Energy, and Transportation 

Management, was signed in 2007, building on a body of federal work aimed at improving 

environmental and energy performance. It directs federal agencies to implement a 

number of sustainable practices, including “energy efficiency and reductions in 

greenhouse gas emissions,” and “use of renewable energy” 

• EO 13514, Federal Leadership in Environmental, Energy, and Economic Performance, 

was signed in 2009 and establishes greenhouse gas (GHG) emission reductions as an 

overarching, integrating performance metric for all federal agencies.

The Energy Policy Act of 2005 also requires federal agencies to reduce their internal energy use 

by 30% by 2015 and obtain 7.5% of their energy needs from renewable sources by 2013. 

Through Executive Order 13514 (EO 13514), President Obama established greenhouse gas 

reduction targets for federal agencies. Agencies submitted their draft inventory and plans to the 

U.S. Department of Energy (DOE) on Feb. 1, 2011. 

The Department of the Interior and U.S. DOE are signatories to a memorandum of understanding 

promoting joint efforts to, among other things, “evaluate the use of nonhydropower renewable 

resources with water management operations.”

It is a Department of the Interior priority goal to increase approved capacity for production of 

renewable (solar, wind, and geothermal) energy resources on Department of the Interiormanaged lands to at least 10,000 MW by the end of 2012. 

Reclamation, while primarily a water and hydropower management agency, holds lands that may 

be well suited to wind and/or solar power installations (typically, greater than 1 MW) insofar as 

these lands: 

• Are in parts of the West receiving abundant solar radiation and wind 
2 

• Have good road access but restricted public access

• Are often adjacent to power plants, substations, pumps, transmission lines, or other 

components of the energy grid. 

In addition, Reclamation has a number of facilities, such as visitor centers, which may be 

suitable for deployment of renewable energy and energy efficiency technologies. 

Reclamation is also developing rural water projects that may be suitable for deployment of a 

variety of renewable energy technologies. 

To this end, Reclamation and NREL entered into an interagency agreement in mid-2011 for 

Reclamation to obtain technical assistance from NREL. NREL is supporting Reclamation 

through four primary activities: 

1. Technical Assistance. Provide Reclamation with assistance on renewable energy 

deployment activities, including: resource screening, estimation of generation potential 

from wind and solar on Reclamation lands, integration of wind and solar into existing 

hydro generation, technology evaluation of advanced hydro technologies, and suitability 

of renewable energy technologies for use at Reclamation facilities such as dams, 

buildings, pumps and visitor centers. 

2. Acquisition and Financing Strategies. Develop strategies to assist Reclamation to 

understand the various options of deploying renewable energy technologies on 

Reclamation-owned lands or facilities. Potential strategies include direct leasing of land 

or identifying interest in third-party financing of projects on Reclamation lands or 

facilities.

3. Technology Training. Provide staff training on renewable energy technologies, 

including wind, hydro, solar, transmission and other topics as may be requested by 

Reclamation. 

4. Program Management and Coordination. Manage the work to be performed under the 

Agreement. Provide integrated technical and policy program support and ensure 

coordination of Reclamation activities across the Department of the Interior and the DOE 

technology programs (e.g., Solar, Wind and Water Power, Federal Energy Management 

Program, Tribal, Geothermal).

This report represents the major deliverable under the technical assistance portion of the 

interagency agreement.
3 

2 Solar Technology Overview

2.1 Introduction

Two general technology approaches exist to creating electricity using solar energy. The first 

approach, termed solar thermal or concentrating solar power (CSP), converts the sun’s energy 

into heat which is used to create steam that then drives a conventional generator. With the 

exception of dish Stirling technology, CSP technologies are generally best suited for utility-scale 

applications.

The second approach, photovoltaics (PV), uses panels comprised of special semiconductor 

material that converts light directly into electricity. PV is very modular and is used in application 

sizes ranging from individual devices (such as calculators) through facility-scale to utility-scale 

applications.

2.2 Solar Thermal (Concentrating Solar Power) Technologies

The three principal CSP technologies use direct normal insolation, which is defined as the rate of 

delivery of solar radiation directly from the sun per unit of surface. These technologies make 

little use of indirect insolation, which is the portion of solar radiation that comes from the parts 

of the sky where the sun is not located and also radiation that is reflected off the ground. 

2.2.1 Parabolic Trough

Most commercial systems to date are parabolic trough systems that reflect and focus sunlight 

onto a linear receiver tube (Figure 2-2). The receiver contains a high-temperature fluid that is 

heated by sunlight and then pumped through a heat exchanger with water to produce superheated 

steam that drives the turbine generator. The parabolic trough CSP technology has been in 

commercial operation in southern California since 1981 (nine plants with a total of 350 MW). 

The latest CSP trough plant in southern Nevada, Nevada Solar One (64 MW), came on line in 

2009. Figures 2-1 and 2-2 show schematics of a thermal electric CSP power tower. Figures 2-3, 

2-4, and 2-5 show photographs of operating trough plants. 
4 

Figure 2-1. Parabolic troughs are aligned north-south and track the sun from east to west

Source: Josh Bauer, NREL 

Figure 2-2. Schematic of a CSP thermal electric plant that can also use thermal storage

Source: Alfred Hicks, NREL
5 

Figure 2-3. 280 MW Arizona trough plant. Photo by Dennis Schroeder, NREL 20097

Figure 2-4. Aerial view of CSP trough plants at Kramer Junction, California (in operation for 30 

years). Photo by Warren Gretz, NREL 01225
6 

Figure 2-5. Solar trough at a 50 MW plant. Photo by Geri Kodey, NREL 14390

2.2.2 Power Tower

The second type of CSP thermal electric plant is called a power tower. A solar power plant 

utilizes hundreds of ground-mounted two-axis tracking mirrors called heliostats that focus 

sunlight on a receiver at the top of the tower, which is 100–300 feet high. In the receiver, a heat 

transfer fluid, commonly molten salt, is heated into liquid form and piped to a steam generation 

system to produce superheated steam. The superheated steam drives a Rankine cycle turbine 

generator to produce electricity. This technology is currently becoming commercialized and 

financeable. A 377 MW three-tower plant is being constructed on BLM lands in Ivanpah, 

California. Figure 2-6 and Figure 2-7 show demonstration solar power tower plants. 
7 

Figure 2-6. DOE solar demonstration power tower in southern Nevada. Photo from Sandia National 

Laboratories, NREL 06051

Figure 2-7. Aerial view of Daggett, California, DOE solar demonstration power tower. Photo by Joe 

Flores, NREL 02163

2.2.3 Dish Stirling

The third CSP technology is the dish Stirling engine system (Figure 2-8 and Figure 2-9). This 

technology uses a parabolic dish or mirrors to direct and concentrate sunlight onto a single-stroke 

Stirling engine. This engine powers an alternator to generate electricity.
8 

Figure 2-8. Characteristics of a CSP dish engine system

Source: Josh Bauer, NREL 

Figure 2-9. 1.5-MW Maricopa, Arizona, solar power plant–60 25-kW dish Stirling systems. Photo by 

David Hicks, NREL 18379
9 

2.3 Photovoltaic Technologies

Photovoltaics are semiconductor devices that convert sunlight directly into electricity. They do 

so without any moving parts and without generating any noise or pollution. They must be 

mounted in unshaded locations—rooftops, carports, and ground-mounted arrays are common 

mounting locations. PV is highly scalable, suitable for both facility- and utility-scale 

applications.

2.3.1 How Solar Cells Work

Solar PV technology converts energy from solar radiation directly into electricity. Solar PV cells 

are the electricity-generating component of a solar energy system. When sunlight (photons) 

strikes a PV cell, an electric current is produced by stimulating electrons (negative charges) in a 

layer in the cell designed to give up electrons easily. The existing electric field in the solar cell 

pulls these electrons to another layer. By connecting the cell to an external load, this current 

(movement of charges) can then be used to power the load, e.g., light bulb (see Figure 2-10). 

Figure 2-10. Generation of electricity from a PV cell

2.3.2 PV System Components

PV cells are assembled into a PV panel or module. PV modules are then connected to create an 

array. The modules are connected in series and then in parallel as needed to reach the specific 

voltage and current requirements for the inverter. The direct current (DC) electricity generated 

by the array is then converted by an inverter to useable alternating current (AC) that can be 

consumed by interconnected buildings and facilities or exported to the electricity grid (see Figure 

2-11). PV system size varies from small residential [2-10 kilowatts (kW)], commercial (100-500 

kW), to large utility scale [1-100+ megawatts (MW)]. 

PV systems have the following components: 

• PV arrays that convert light energy to DC electricity 
10 

• Inverters that convert DC to AC, and provide important safety, monitoring, and control 

functions 

• Various wiring, mounting hardware, and combiner boxes 

• Monitoring equipment. 

PV Array. The PV array, which is the primary component of a PV system, converts sunlight to 

electrical energy; all other components simply condition or control energy use. Most PV arrays 

consist of interconnected PV modules that range in size from 50 to 300 peak DC watts. Peak 

watts are the rated output of PV modules at standard operating conditions of 25°C (77°F) and 

insolation of 1,000 watt/square-meter (W/m2). Because these standard operating conditions are 

nearly ideal, the actual output will be less under typical environmental conditions. PV modules 

are the most reliable components in any PV system. They have been engineered to withstand 

extreme temperatures, severe winds, and impacts. PV modules have a life expectancy of over 30 

years, and manufacturers warranty them against power degradation for 20-25 years. The array is 

usually the most expensive component of a PV system, typically accounting for approximately 

two-thirds the cost of a grid-connected system. 

Inverters. PV arrays provide DC power at a voltage that depends on the configuration of the 

array. This power is converted to AC at the required voltage and number of phases by the 

inverter. Inverters enable the operation of commonly used equipment such as appliances, 

computers, office equipment, and motors. Current inverter technology provides true sine wave 

power at a quality often better than that of the serving utility. A location for the inverter along 

with the balance of the system equipment should be considered. 

Inverters are available that include most or all of the control systems required for operation, 

including some metering and data-logging capability. Inverters must provide several operational 

and safety functions for interconnection with the utility system. The Institute of Electrical and 

Electronics Engineers, Inc. (IEEE) maintains standard P929, Recommended Practice for Utility 

Interface of Photovoltaic Systems, which allows manufacturers to write “Utility-Interactive” on 

the listing label if an inverter meets the requirements of frequency and voltage limits, power 

quality, and nonislanding inverter testing. Underwriters Laboratory maintains standard UL 1741, 

Standard for Static Inverters and Charge Controllers for Use in Photovoltaic Power Systems, 

which incorporates the testing required by IEEE P929 and includes design (type) testing and 

production testing. There is a large choice of inverter manufacturers, although it is recommended 

that the inverter be approved by Go Solar California.2

2.3.3 Facility-Scale PV

The amount of energy produced by a PV panel depends on several factors, including type of 

collector, tilt and azimuth of the collector, temperature, level of sunlight, and weather conditions. 

An inverter is required to convert DC to AC. A transformer may or may not be needed to change 

the inverter output voltage to a voltage compatible with building and utility power systems. The 

balance of the system consists of conductors/conduits, switches, disconnects, and fuses. Gridconnected PV systems feed power into the facility’s electrical system and do not typically 

 

2

 “List of Eligible Inverters per SB1 Guidelines.” Go Solar California, 2007-2012. 

http://www.gosolarcalifornia.org/equipment/inverters.php. 
11 

include batteries unless backup power is desired. Figure 2-11 shows the major components of a 

grid-connected PV system and illustrates how these components are interconnected.

Figure 2-11. Depiction of major components of grid-connected PV systems

Source: Alfred Hicks, NREL

PV panels are very sensitive to shading. When shade falls on a panel, that portion of the panel is 

no longer able to collect the high energy beam radiation from the sun. PV panels are made up of 

many individual cells that each produce a small amount of current and voltage. These individual 

cells are connected in series to produce a larger current. If an individual cell is shaded, it will act 

as a resistance to the whole series circuit, impeding current flow and dissipating power rather 

than producing it. By estimating the amount of shading, the NREL team can determine whether 

the area is appropriate for solar panels. 

If a site is found to have good potential for a PV system, the next step is to determine the size of 

that system. This is highly dependent on the average energy use of the facilities on the site. It is 

generally not advisable to provide more power than the site will use due to the economics of 

most net-metering agreements. 

2.3.4 Utility-Scale PV

Utility-scale PV systems are growing in number and benefit from economies of scale to reduce 

the dollar per watt cost of large-scale plants. Although PV provides variable power, the 

technology is financeable and the cost of PV modules has dramatically dropped in the last few 

years.
12 

Figure 2-12. Ground mount array diagram 

Source: Kosol Kiatreungwattana, NREL, EPA Photovoltaic Solar on Landfills Technical Guidance (forthcoming)

In the 1980s and 1990s, due to the high cost of PV systems (≥$10/W) most PV installations were 

small roof-mounted or ground-mounted systems. Today, due to dramatic reductions in PV 

system costs ($3-4/W), private and federal landowners are developing utility-scale 50-200 MW 

PV plants. 

The typical choices are equator-facing rows of fixed panels tilted at 10-30 degrees or single-axis 

tracking arrays oriented north-south that tilts from east to west during the day to track the sun. 

Single-axis tracking PV systems use 10% more land to minimize adjacent panel shading; 

however, the cost increase over fixed panels is small (10%) and the system produces up to 35% 

more electrical energy. Two such installations are shown in Figure 2-13 and Figure 2-14. 
13 

Figure 2-13. 8 MW, single-axis tilt-PV system in Alamosa, Colorado. Photo by Tom Stoffel, 

NREL 15558

Figure 2-14. Photovoltaic field at the National Wind Technology Center. Photo by Dennis 

Schroeder, NREL 19794

2.4 Government Incentives for Solar Energy Plants

Like most renewable technologies, there are market driving policies. The main driver has been 

state renewables portfolio standards (RPS), where utility companies are mandated to increase 

power generation from renewable energy resources. State and utility financial incentives, and 

state and federal tax incentives are also allowing the utility-scale solar power cost of electrical 

generation to approach that of conventional fossil fuel-generation plants. 

2.4.1 Federal and States Incentives 

Federal incentives for corporate sector-developed utility-scale solar projects include:

• Federal Investment Tax Credit: 30% of cost basis, expires 2016 
14 

• 5-year Accelerated Depreciation: no expiration

Arizona incentives for corporate-sector developed projects include: 

• Renewable Energy Production Tax Credit, where: 

o Minimum size is 5 MW

o Maximum incentive of $2 million per year 

• Program budget of $20 million per year on first come, first serve basis (timing is critical)

o Energy Equipment Property Tax Exemption: 100% of asset value 

o Solar Equipment Sales Tax Exemption: 100% of sales tax on equipment 

The financial and tax incentives for solar equipment for all states with Reclamation lands or 

facilities are provided at http://www.dsireusa.org/incentives/index.cfm?state=us&re=1&EE=1. 
15 

3 Wind Technology Overview

3.1 Introduction

Wind turbines convert the mechanical motion of moving air into electricity. While not as 

modular as PV, wind turbines come in a range of sizes ranging from small units with a rated 

power of a few hundred watts that provide energy to yachts or cabins, to large units with a rated 

power of several megawatts that provide bulk energy to the grid. While turbines of all sizes have 

the same basic physics, turbines can be grouped into three size classes, small, medium, and large, 

each subject to very different sets of market forces.

3.2 How Wind Turbines Work

3.2.1 Wind Turbine Topologies

Wind turbine design involves difficult trade-offs. While horizontal-axis, three-bladed upwind 

machines are most common, wind turbines employing a variety of topologies have been 

deployed. This section describes the major categories of machines.

Drag versus lift: Drag machines use the wind to push the blades. Lift machines use the wind to 

lift the blades, with similar physics to that of an airplane wing. Lift machines are much more 

efficient than drag machines, and thus the vast majority of wind turbines on the market are lift 

machines. An example of a drag machine is the classic water pumping wind mill. Drag machines 

typically have high solidity (i.e. the blades cover most or all of the swept area. Lift machines 

typically have two or three blades. Drag machines always have a tip speed ratio of less than one. 

In other words, the speed of the blade tip is always less than the wind speed. In contrast, lift 

machines have a tip speed ratio greater than one (i.e., the speed of the tip of the blade is greater 

than the wind speed). It is this higher tip speed ratio that accounts for the greater efficiency of lift 

machines. Drag machines do have the advantage of greater torque, something that is useful in 

direct mechanical water pumping applications.

Vertical axis versus horizontal axis: Vertical axis wind turbines have an axis of rotation that is 

vertical, while horizontal-axis turbines have an axis of rotation that is horizontal. An advantage 

of vertical-axis turbines is that much of the heavy equipment such as the generator can be located 

close to the ground. This is also a big disadvantage. Being located closer to the ground, verticalaccess turbines are not exposed to the greater wind resource that is located higher off the ground 

and thus produce less energy than a comparable horizontal-axis wind turbine. Despite longstanding interest and the introduction of several small vertical-axis turbines in recent years, 

horizontal-axis turbines dominate the market.

Upwind versus downwind: Upwind machines have the blades upwind of the tower. Downwind 

machines have the blades downwind of the tower. Especially on larger machines, the force of the 

wind on the blades causes the blades to bend in the downwind direction. The blades in upwind 

machines need to be stiff enough to avoid bending so much that they hit the tower. In downwind 

machines the blades bend away from the tower and thus don’t have to be as stiff, which reduces 

materials costs. A disadvantage of the downwind configuration is tower shadow. As the blades 

go behind the tower, they are partially sheltered from the wind. This sheltering leads to cyclic 

loads on the blades that can lead to increased maintenance requirements. While there is 
16 

continuing interest in downwind machines and downwind machines are available, especially in 

the small turbine category, most wind turbines use the upwind configuration. 

Two blades versus three blades: The advantage of two-bladed machines is cost. Two blades are 

less expensive than three blades. The disadvantage of two-bladed machines is that the 

gravitational forces on the rotor are different when the blades are horizontal as compared to 

when the blades are vertical. Thus as the rotor spins, two-bladed machines are subject to cyclic 

loads that can lead to more wear and tear. A three-bladed rotor is always balanced, regardless of 

blade orientation and is thus subject to fewer cyclic loads. Three-bladed machines dominate the 

market. Interest remains in two-bladed machines, and some two-bladed models are available in 

the market.

3.2.2 Wind Turbine Components

All turbines work by converting the energy in moving air into electricity. Figure 3-1 shows the 

major wind turbine components of a utility-scale turbine. The blades, comprising the rotor, 

capture energy from the wind. The rotor is connected via a shaft to the generator, which converts 

the shaft’s rotation into electricity. In smaller turbines and in some larger turbines, the shaft is 

directly connected to the generator. This configuration is called direct drive. In most larger 

turbines the rotor is connected to the generator via a gearbox, which increases the rotational 

speed to a value more suitable for typical generators. Most turbines include a brake on either the 

low speed or high speed shaft. The shaft(s), brakes, gearbox, and generator together comprise the 

drive train, which is typically housed within a nacelle that protects the drive train components 

from the elements. The nacelle is mounted on a tower that exposes the turbine to the higher wind 

speeds that are typically found higher off the ground. 

Large turbines typically have an active yaw system (a yaw drive, powered by a yaw motor), that 

orients the turbine into the wind. The motor is controlled by a signal coming from a wind vane 

mounted on top of the nacelle. A nacelle-mounted speed sensor signals the rotor to start spinning 

when the wind speeds are above the minimum “cut-in” wind speed, typically about 8 mph. 

Signals from the speed sensor will cause the turbine to shut off if the winds exceed the turbine’s 

“cut-out” speed, typically around 50 mph. 

Small turbines (up to 10-20 kW in rated power) typically have passive yaw systems (no yaw 

drive or yaw motor) and use a tail to orient the rotor into the wind. These small turbines also use 

passive strategies to protect themselves from extreme winds. A common strategy is furling, 

where the force from high winds causes the turbine nacelle to tilt out of the wind. Other passive 

protection strategies involve twisting the blades in high winds to reduce the blade’s lift and thus 

reduce the forces on the turbine. 
17 

Figure 3-1. Large wind turbine components 

Source: DOE/EERE 

3.2.3 Wind Turbine Siting

The power in the wind is proportional to the cube of the velocity. This means that a 10% increase 

in wind speed results in a 30% increase in power. The take away is that the key consideration in 

siting a wind turbine is to place it in a location with a good wind resource. For maximum energy 

production, a wind turbine should be away from or above any ground obstacles (ground clutter) 

that could cause local turbulence. Figure 3-2 shows the zone of turbulent winds that is typically 

found downwind of buildings and trees. For utility-scale turbines, ground clutter is typically not 

an issue as these turbines are mostly located outside of urban areas in locations with good wind 

exposure. Ground clutter is more of an issue for smaller turbines that provide energy to a specific 

load. Ideally, the turbine should be located upwind of the load (per the prevailing wind direction) 

and on a tower taller than any other building or tree within several hundred meters. However, 

given on-the-ground realities, the best available turbine location on a given property may not 

meet the criteria for ideal siting. In this case, the prospective turbine owner should realize that 

the turbine energy production will suffer and determine if the project is still worthwhile.
18 

Figure 3-2. Wind turbine siting

Source: OpenEI

3.3 Wind Turbine Market and Applications

3.3.1 Introduction

Wind turbines can be loosely grouped into three different size categories, small, medium, and 

large. Each have different applications, and encounter different regulatory and market 

environments. 

3.3.2 Small Wind Turbines 

There is no universally accepted maximum cutoff for small wind turbines. For this publication, a 

small turbine is defined as a turbine with a rated power less than 100 kW. Turbines within this 

category are mostly used to power a specific load such as a cabin, house, farm, commercial 

facility, or industrial facility. Economically, these turbines are competing against retail electricity 

rather than wholesale electricity. Because most infrastructure is located in less windy areas, 

small turbines are more likely to be placed in less windy locations and in spots that are subject to 

the effects of ground clutter. Thus, small turbines tend to have lower capacity factors than larger 

turbines. 

Small turbine design at the small end of this category typically emphasizes maximum reliability 

and a minimum number of moving parts. As can be seen, there are many fewer parts than for 

larger turbines. Figure 3-3 shows a schematic of a small turbine. Figure 3-4 shows a couple of 

sample small wind turbines. Small turbines are mounted on either monopole or lattice towers. 

Less expensive guyed towers (monopole or lattice) are commonly used for the smaller turbines 

in this category. 

A dizzying variety of turbines rated up to 20 kW is available in the small end of the small 

category. Above 20 kW there are fewer choices. At the larger end of this category there is an 

active market in refurbished turbines. The original 1980’s wind farms that used the then current 

50-100 kW wind turbines are being “repowered” with modern, multi-MW, turbines. The usable 
19 

old turbines are being refurbished and sold on the secondary market. Cost and quality of these 

refurbished turbines vary drastically. 

Figure 3-3. Basic parts of a small wind turbine 

Source: OpenEI

Figure 3-4. Examples of small wind turbines. Photos by (left) Abigail Krich, NREL 13491, and 

(right) Lee Jay Fingersh, NREL 14642
20 

3.3.3 Large Wind Turbines

The size of utility-scale turbines has steadily increased since these turbines were first deployed in 

the early 1980s. Since then, turbine-rated power has increased from 50 kW to over 3 MW. 

Similar to the situation with small turbines, there is no universally accepted definition of a large 

wind turbine. This paper will categorize as “large” or “utility scale” any turbine with a rated 

power greater than 1 MW. Current utility-scale turbine blade length ranges from 35 meters (m) 

to over 50 m. Hub heights range from 60 m to over 100 m. The overwhelming majority of large 

turbines are mounted on steel monopole towers. Large turbines are deployed in projects using 

anywhere from one to several hundred turbines. These projects supply bulk power to the grid and 

thus compete in the wholesale electric market. Since these projects are not tied to a specific load, 

project developers have more flexibility to select the windiest sites. The largest portion of large 

turbine projects is owned by independent power producers (IPPs) that sell electricity to utilities 

under long-term (10-20 year) power purchase agreements. A significant minority of projects are 

owned directly by utilities. Figure 3-5 shows a schematic of a wind farm. Figure 3-6 shows a 

couple of example utility-scale wind turbine installations. 

Figure 3-5. Wind farm schematic

Source: DOE/EERE 
21 

Figure 3-6. Large wind turbines. Photos by (left) Dennis Schroeder, NREL 19022, and (right) Ruth 

Baranowski, NREL 21207 

3.3.4 Mid-Size Wind Turbines 

For the purposes of this publication, turbines with a rated power of 100 kW–1000 kW comprise 

the category of mid-size wind turbines. Turbines of this size range are not as competitive as 

larger turbines for providing bulk power, while the applications that require mid-size turbines are 

fewer in number compared to the number of small turbine applications. Most newly installed 

turbines in this category supply electricity to a specific load. Performance and economics of midsize turbines are between those of the large and small turbines. As can be expected, the larger 

mid-size turbines are similar to large turbines, while the smaller mid-size turbines are similar to 

the (larger) small turbines. This size market segment is not as active as the large and small 

turbine market segments. The lower level of activity means that there are only a few suppliers 

manufacturing new turbines in this size range. This market segment sees steady business in 

refurbished older machines. Figure 3-7 shows a sample mid-size wind turbine. 
22 

Figure 3-7. Mid-size wind turbine. Photo by Lee Jay Fingersh, NREL 16641

3.4 Government Incentives for Wind Energy Projects

Like most renewable technologies, there are market driving policies to encourage wind turbine 

deployment. A large driver has been state RPSs, where utility companies are mandated to 

increase power generation from renewable energy resources. State and utility financial 

incentives, and state and federal tax incentives are also allowing the utility-scale wind power cost 

of electrical generation to approach that of conventional fossil fuel-generation plants. 

3.4.1 Federal Incentives 

Federal incentives for corporate sector developed utility-scale solar projects include:

• Federal Investment Tax Credit (turbines up to 100 kW): 30% of cost basis, expires 2016. 

• Production Tax Credit: $0.022 (escalating with inflation) for each kWh sold to an unrelated 

third party for the first 10 years of the facility. Facilities must begin construction by Dec. 31, 

2013 to qualify. The credit may be extended. 

• 5-year Accelerated Depreciation: No expiration. 

The financial and tax incentives for solar equipment for all states with Reclamation lands or 

facilities are provided at http://www.dsireusa.org/incentives/index.cfm?state=us&re=1&EE=1. 
23 

4 GIS Screening

4.1 Utility-Scale Screening

A utility-scale screening was conducted to broadly identify the renewable energy potential for 

Reclamation lands. Reclamation provided a generalized representation of its land interests in the 

17 western states, depicting the survey sections that contained some Reclamation lands of 

interest. Individual sites were not specified. The analysis was subdivided into state and countylevel tables to aid in reporting and ranking individual areas. This analysis is intended to provide 

general information on renewable energy resource intensity in different regions of interest to 

Reclamation, with the potential for more detailed analysis of specific areas of interest. State-level 

maps and overall tables are fully presented in the separate publication titled “Renewable Energy 

Assessment of Bureau of Reclamation Land and Facilities Using Geographic Information 

Systems.”3

This analysis examined potential resource intensity for CSP, utility-scale solar PV, and onshore 

wind. NREL used resource exclusion scenarios developed for characterizing overall technical 

potential in its resource assessments and modeling. The exclusion scenarios are described in 

Appendix A of “Renewable Energy Assessment of Bureau of Reclamation Land and Facilities

Using Geographic Information Systems.” Other site-based characteristics (proximity to 

transmission lines and roads) were omitted because the specific locations of the Reclamation

land interests were unknown. 

4.1.1 Concentrating Solar Power

CSP is power generated from a utility-scale solar power facility in which the solar heat energy is 

collected in a central location. The resource potential estimates utilize annual average direct 

normal solar radiation produced by the State University of New York–Albany and NREL4

. The 

data are modeled at a 10-km horizontal resolution and are averaged over the period from 1998 to 

2005. The resource areas have been filtered to identify only the areas that are more likely to be 

developed based on their resource intensity and general site characteristics. The minimum annual 

average resource value used is 6 kWh/m2

/day. The site exclusion criteria are detailed in the 

separate publication. Site characteristics that are incompatible with utilization for solar power

include steeply sloped areas, urban areas, and protected environmental areas. 

A trough system, dry-cooled with 6 hours of storage and a solar multiple of 2.0, was used in 

NREL’s System Advisor Model (SAM) (https://sam.nrel.gov) to estimate generation capacity 

factor values within five solar resource ranges. An overall installation density of 32.8 

MW/square-kilometer (km2

) was also estimated for this configuration.

4.1.2 Utility-Scale Photovoltaics

Utility-scale PV is defined as large-scale PV deployed outside urban boundaries, as defined by 

the U.S. Census Bureau’s urbanized area boundaries data set (http://www.census.gov/geo/www). 

The data used to represent this resource is a single-axis tracking collector at a 0-degree tilt with a 

 

3 Haase, et al. Renewable Energy Assessment of Bureau of Reclamation Land and Facilities Using Geographic 

Information Systems (forthcoming). NREL/TP-7A30-57123. Golden, CO: National Renewable Energy Laboratory. 4 Wilcox, S. National Solar Radiation Database 1991-2005 Update: User's Manual. NREL/TP-581-41364. Golden, 

CO: National Renewable Energy Lab, 2007. http://www.nrel.gov/docs/fy07osti/41364.pdf. 
24 

48 MW/km2 power density5

. The site characteristic exclusion criteria utilized are the same as 

described for CSP, and the minimum annual average resource value used is 6 kWh/m2

/day. 

State-level annual capacity factors were generated using the National Solar Radiation Database 

Typical Meteorological Year 3 (TMY3) data set (see Table A-3 from “Renewable Energy 

Assessment of Bureau of Reclamation Land and Facilities Using Geographic Information 

Systems.”6

) and SAM. 

4.1.3 Onshore Wind

The onshore wind resource was calculated for wind at 80 m height above the ground, 

extrapolating from validated onshore wind power estimates at 50 m height. These data were

compiled from several sources that have released their data to NREL for use in its modeling 

efforts. These sources include NREL’s internal modeling (North Dakota, South Dakota, and 

portions of Texas), Alternative Energy Institute (Texas), and AWS Truepower with NREL (the 

remaining 14 states). The 50-m estimates were shifted to 80 m height by increasing the resource 

by 1⁄2 power class for those areas below 500 W/m2

 annual average wind power density. A 

resource threshold of class 3 or better was applied, and site characteristic exclusions were 

applied as detailed in Table A-4 of “Renewable Energy Assessment of Bureau of Reclamation 

Land and Facilities Using Geographic Information Systems.” In estimating generation from wind 

resource areas, capacity factors by class were utilized, representing estimates for typical utilityscale wind turbines within that resource profile (Table A-5 of “Renewable Energy Assessment of 

Bureau of Reclamation Land and Facilities Using Geographic Information Systems.”). A power 

density of 5 MW/km2 was used,

7

 representing a turbine spacing of 10x10 rotor diameters. 

4.2 Results

“Renewable Energy Assessment of Bureau of Reclamation Land and Facilities Using 

Geographic Information Systems.” includes summaries of the resource potential with and 

without exclusions to demonstrate the impact of the exclusion scenarios utilized. The top 20 

counties for solar and wind (based on total potential installed capacity) are shown in Figure 4-1. 

Table 4-1, Table 4-2, and Table 4-3 list the top 20 counties for CSP, utility-scale PV, and 

onshore wind, respectively. NREL was not provided the actual Reclamation land area, but rather 

the boundaries that were provided were public land survey sections (each section consisting of 

640 acres/1 square mile) that contained some portion of Reclamation-owned lands. The exact 

amount of Reclamation-owned land within each section is unknown. Thus, the MW values 

shown represent the potential capacity within the land survey sections provided by Reclamation 

within a county, not just Reclamation lands. Therefore, the potential installed capacity estimates 

are slightly high, serving as an index of the relative potential in areas owned by Reclamation. 

Additional site-specific analyses would be required to determine the suitability and potential of 

actual Reclamation lands. 

 

5 Denholm, P.; Margolis, R. M. “Impacts of Array Configuration on Land-Use Requirements for Large-Scale 

Photovoltaic Deployment in the United States.” Preprint. Prepared for SOLAR 2008-American Solar Energy 

Society, May 3–8, 2008. NREL/CP-670-42971. Golden, CO: National Renewable Energy Laboratory, May 2008. 

http://www.nrel.gov/docs/fy08osti/42971.pdf. 6 Haase, et al. Renewable Energy Assessment of Bureau of Reclamation Land and Facilities Using Geographic 

Information Systems (forthcoming). NREL/TP-7A30-57123. Golden, CO: National Renewable Energy Laboratory. 7 DOE EERE. 20% Wind Energy by 2030: Increasing Wind Energy's Contribution to U.S. Electricity Supply.

NREL/TP-500-41869. Golden, CO: National Renewable Energy Laboratory, July 2008; pp. 179.
25 

Figure 4-1. Summary of top 20 counties and top 20 facilities (by technology) for potential 

renewable energy deployment

As shown in the figure and tables, southern Arizona and southeast California show good promise 

for both CSP and PV. Western Nevada and southwest Wyoming also have promising parcels for 

CSP, while additional promising sites for PV are located in southern New Mexico. The 
26 

Reclamation parcels with the greatest wind resource are generally located in the northern Rocky 

Mountains and northern plains (Wyoming, Montana, and North Dakota). 

Table 4-1. Top 20 Counties by CSP Potential Installed Capacity

CSP

County MW Rank

MW Capacity for Reclamation Area of 

Interest (by County)

a

Churchill, NV 1 44,432

Lyon, NV 2 43,544

Pershing, NV 3 42,899

Imperial, CA 4 26,720

Yuma, AZ 5 22,688

La Paz, AZ 6 21,593

Maricopa, AZ 7 14,599

Pinal, AZ 8 11,856

Pima, AZ 9 8,125

Washoe, NV 10 7,434

Riverside, CA 11 5,934

Delta, CO 12 5,386

Montrose, CO 12 5,386

Eddy, NM 14 4,547

Loving, TX 14 4,547

Reeves, TX 14 4,547

Lander, NV 17 2,204

Lincoln, WY 18 1,926

Sweetwater, WY 18 1,926

San Bernardino, CA 20 1,605

Clark, NV 20 1,605 a Listed capacities are for an area somewhat larger than actual Reclamation-owned land. For more 

details, see section 4.2 Results. 

Table 4-2. Top 20 Counties by Utility-Scale PV Potential Installed Capacity

Utility-Scale PV

County MW Rank

County-Level MW Potential for 

Reclamation Area of Interesta

Imperial, CA 1 38,990

Yuma, AZ 2 33,106

La Paz, AZ 3 31,508

Maricopa, AZ 4 21,303

Pinal, AZ 5 17,301

Pima, AZ 6 11,856

Churchill, NV 7 11,189

Riverside, CA 8 8,659

Eddy, NM 9 6,635
27 

Utility-Scale PV

County MW Rank

County-Level MW Potential for 

Reclamation Area of Interesta

Loving, TX 9 6,635

Reeves, TX 9 6,635

San Bernardino, CA 12 2,341

Clark, NV 12 2,341

Saguache, CO 14 1,891

Sierra, NM 15 1,733

Socorro, NM 15 1,733

De Baca, NM 17 1,519

Chaves, NM 18 1,389

Gila, AZ 19 1,294

Lyon, NV 20 1,002 a Listed capacities are for an area somewhat larger than actual Reclamation-owned land. For more 

details, see section 4.2 Results. 

Table 4-3. Top 20 Counties by Wind Potential Installed Capacitya

Big Horn, WY 1 2,975

Park, WY 1 2,975

Hill, MT 3 1,370

Liberty, MT 4 1,336

Sheridan, ND 5 1,201

Carbon, WY 6 1,152

Natrona, WY 6 1,152

Chouteau, MT 8 1,023

Wells, ND 9 967

Greer, OK 10 922

Burleigh, ND 11 829

McLean, ND 11 829

Red Willow, NE 13 748

Phillips, MT 14 715

Valley, MT 15 694

Blaine, MT 16 671

Eddy, ND 17 663

Toole, MT 18 645

Jackson, OK 19 612

Grant, WA 20 571 a

 Listed capacities are for an area somewhat larger than actual Reclamation-owned land. For more 

details, see section 4.2 Results. 
28 

4.3 Facility-Scale Screening

Facility-scale screening of selected locations has begun with the extraction of resource 

information from NREL databases. Reclamation selected 748 locations from its property 

database and provided NREL with the real property identifier, address (where available and not 

sensitive), city, state, and zip code. This information was georeferenced by NREL to establish 

specific coordinates to represent the locations, with the accuracy of that location dependent on 

the level of specificity of the address. In many cases, multiple real property identifiers are 

associated with the same location due to the structure of the addressing and location information 

given. Results for all properties are given in the related publication titled “Renewable Energy 

Assessment of Bureau of Reclamation Land and Facilities Using Geographic Information 

Systems.”8 Table 4-4, Table 4-5, and Table 4-6 show some of these results for the properties 

with the highest annual average potentials for energy delivered utilizing solar vent preheating to 

preheat air coming into a facility and for PV solar resources. The top 20 locations (for each 

technology) are also shown in Figure 4-1. 

As shown in the figure and tables the facilities with the greatest PV resource are located in the 

southern Arizona and New Mexico. The facilities with the greatest resource for solar vent preheating are in an area extending from northern New Mexico to southern Wyoming. The facilities 

with the greatest wind resource are located in the northern plains states (Wyoming and North 

Dakota). 

Other data extracted from the database that are included in the separate publication are annual 

global horizontal solar resource, annual solar resource from an east-west oriented single-axis 

tracking collector, maximum solar resource from a fixed flat-plate system with tilt equal to 

latitude, and annual heating degree days and annual cooling degree days (both relative to 65 

degrees).

These sites represent potential sites that can be further evaluated for deployment of facility-scale 

renewable energy systems. 

 

8 Haase, et al. Renewable Energy Assessment of Bureau of Reclamation Land and Facilities Using Geographic 

Information Systems (forthcoming). NREL/TP-7A30-57123. Golden, CO: National Renewable Energy Laboratory.
29 

Table 4-4. Reclamation Facilities with the Highest Potential Energy Delivered from Solar Vent 

Preheating 

Real Property 

Identifier City State

Solar Vent 

Preheat 

Annual 

Energy 

Delivered 

(kWh/m2/yr)

N0557000200B Page Arizona 844.0

N0557000400B Page Arizona 844.0

N0557000100B Page Arizona 844.0

N0557000500B Page Arizona 844.0

N0557000300B Page Arizona 844.0

N0382000100B Meredith Colorado 808.0

N0382000400B Meredith Colorado 808.0

N0154000300B Kemmerer Wyoming 805.0

N0154000400B Kemmerer Wyoming 805.0

N0154000200B Kemmerer Wyoming 805.0

N0154000500B Kemmerer Wyoming 805.0

Table 4-5. Reclamation Facilities with the Highest Annual Average Photovoltaic Resource from a 

Fixed Flat-Plate Collector with Tilt Equal to Latitude 

Real Property 

Identifier City State

Tilt = 

Latitude 

Solar 

(Annual 

Average 

kWh/m2/day)

N0423000100B Ehrenberg Arizona 6.55

N0423000200B Ehrenberg Arizona 6.55

N0423000300B Ehrenberg Arizona 6.55

N0423000400B Ehrenberg Arizona 6.55

N0163202500B Socorro New Mexico 6.55

N0024000100B Truth Or 

Consequences

New Mexico 6.54

N0024000200B Truth Or 

Consequences

New Mexico 6.54

N0024000300B Truth Or 

Consequences

New Mexico 6.54

N0024000400B Truth Or 

Consequences

New Mexico 6.54

N0024000500B Truth Or 

Consequences

New Mexico 6.54

N0024000600B Truth Or 

Consequences

New Mexico 6.54
30 

Table 4-6. Reclamation Facilities with the Highest Annual Average Wind Resource at 50 m Height 

Above Ground

Real Property 

Identifier City State

Annual Wind 

Power Density 

at 50 m height 

(W/m2)

N0144005000B Mills Wyoming 555

N0144005100B Mills Wyoming 555

N0467006400B Mills Wyoming 555

N1112000100B Elgin North 

Dakota

515

N1112000200B Elgin North 

Dakota

515

N0144000200B Casper Wyoming 477

N0144005600B Casper Wyoming 477

N0144001200B Sinclair Wyoming 476

N0144001300B Sinclair Wyoming 476

N0144001400B Sinclair Wyoming 476

N0144001700B Sinclair Wyoming 476
31 

5 Facility-Scale Assessment of Phoenix Area Office

On Aug. 30, 2011, a team led by NREL together with Reclamation personnel conducted an 

assessment of Reclamation’s Phoenix Area Office building. During the site visit, the team 

identified several suitable locations for grid-connected PV and a possible location for solar hot 

water. 

Reclamation’s Phoenix Area Office is located at 6150 W. Thunderbird Road, Glendale, AZ. The 

structure is a two-story steel frame, exterior masonry office building with roof-mounted 

mechanical equipment. The building faces south, with the main entry on the south side. An aerial 

image of the building and surrounding carports is shown in Figure 5-1, and a south elevation 

view is shown in Figure 5-2. 

The building is 6 years old and has a white membrane roof manufactured by Versico (Carlisle). 

The roof is in excellent condition and has 4 years left under warranty. It is important to confirm 

with the structural engineers that the roof is be capable of supporting a new ballasted PV system 

with a weight of about 4 pounds (lbs)/square-feet (ft2

). NREL believes that it will support such a 

system and has assumed so for this report.

Figure 5-1. Aerial view of Phoenix Area Office 

Source: Google Earth image provided by Reclamation
32 

Figure 5-2. Phoenix Area Office south elevation view. Photo by Otto VanGeet, NREL

5.1 Energy Use and Utility Data

The Phoenix Area Office is connected to the Salt River Project (SRP) electric utility and 

Southwest Gas for natural gas. The electric rate structure is General Service (E36)9

, which is an 

energy (kilowatt-hour)-driven rate (85% of cost is energy) with minimal demand charges (6% of 

cost is demand) and minimal monthly service charges. The highest energy and demand charges 

are during the “summer peak” of July and August (see Figure 5-3 and Figure 5-4). The annual 

electrical energy use was 892,800 kilowatt-hour (kWh) in fiscal year (FY) 2010, and the average 

rate during FY 2010 was $0.09/kWh. 

 

9 For more information, see http://www.srpnet.com/prices/business/general.aspx.
33 

Figure 5-3. Electrical cost (FY06 – FY11)

Figure 5-4. Electrical usage (kWh, FY06 – FY11)a 

a At the time of this writing, only data from September to June was available for FY11.
34 

The annual gas use during FY 2010 was 6,533 therms, and the total annual cost was $8,716 for 

an average of $1.33/therm. Gas is used just for space heating; the minimal amount of domestic 

hot water is generated by an electric water heater. The average cost per therm is high due to the 

monthly meter fee of about $50. 

5.2 Facility-Scale PV Systems

The amount of energy produced by a PV panel depends on several factors, including type of 

collector, tilt and azimuth of the collector, temperature, level of sunlight, and weather conditions. 

An inverter is required to convert DC to AC of the desired voltage compatible with building and 

utility power systems. The balance of the system consists of conductors/conduits, switches, 

disconnects, and fuses. Grid-connected PV systems feed power into the facility’s electrical 

system and do not include batteries. Section 2 Solar Technology Overview provides additional 

detail on the major components and functioning of PV systems. 

PV panels are very sensitive to shading. When shade falls on a panel, that portion of the panel is 

no longer able to collect the high energy beam radiation from the sun. PV panels are made up of 

many individual cells that each produce a small amount of current and voltage. These individual 

cells are connected in series to produce a larger current. If an individual cell is shaded, it will act 

as a resistance to the whole series circuit, impeding current flow and dissipating power rather 

than producing it. By estimating the amount of shading, the NREL team can determine whether 

the area is appropriate for solar panels. 

If a site is found to have good potential for a PV system, the next step is to determine the size of 

that system. This is highly dependent on the average energy use of the facilities on the site. It is 

generally not advisable to provide more power than the site will use due to the economics of 

most net-metering agreements. 

PV systems have the following components: 

• PV arrays that convert light energy to DC electricity

• Inverters that convert DC to AC and provide important safety, monitoring, and control 

functions 

• Various wiring, mounting hardware, and combiner boxes 

• Monitoring equipment. 

5.3 PV Site Location and Performance

The PV arrays must be installed in unshaded locations on the ground or on building roofs that 

have an expected life of at least 25 years. The proposed roof site has excellent annual solar 

access. The predicted array performance was found using PVWatts Version 2 for Phoenix, a 

performance calculator for grid-connected PV systems created by NREL’s Renewable Resources 

Data Center.10

 

10 For more information on NREL’s PVWatts Version 2, see http://www.nrel.gov/rredc/pvwatts/grid.html. 
35 

Table 5-1. Annual AC Energy and Cost Savings Results in kWh/kW for 10-Degree Fixed-Tilt PV 

from PVWatts for Phoenix

City: Phoenix 

State: Arizona 

Latitude: 33.43° N

Longitude: 112.02° W

Elevation: 339 m

PV System Specifications

DC Rating: 1.0 kW

DC to AC Derate Factor: 0.820

AC Rating: 0.8 kW

Array Type: Fixed Tilt 

Array Tilt: 10.0°

Array Azimuth: 180.0°

Energy Specifications

Cost of Electricity: 9.0 ¢/kWh

Results

Month 

Solar 

Radiation

(kWh/m2/day)

AC 

Energy 

(kWh)

Energy 

Value

($)

1 3.93 93 8.37

2 4.99 107 9.63

3 6.03 138 12.42

4 7.54 163 14.67

5 8.19 178 16.02

6 8.21 167 15.03

7 7.82 166 14.94

8 7.39 158 14.22

9 6.70 140 12.60

10 5.68 127 11.43

11 4.37 97 8.73

12 3.62 86 7.74

Year 6.21 1620 145.80

Figure 5-5. Proposed PV system locations for Reclamation’s Phoenix building

Source: Google Earth (modified by Otto VanGeet, NREL) 

The south rooftop area and carports designated for PV installations are flat, have excellent solar 

exposure (see Figure 5-6 and Figure 5-7), and have few existing obstructions. The north, east, 

and west roofs have too much shading for PV. 
36 

5.4 Potential Roof and Carport Areas 

The potential roof area assumes a 4-ft setback from the roof edge. A PV power density of 8 W/ft2

was assumed, which is representative of a crystalline silicon panel tilted at 10 ̊ installed on a 

ballasted racking system similar to GSA Denver Federal Center (Figure 5-6).

Figure 5-6. Typical ballasted PV system at GSA Denver Federal Center (Phoenix Area Office 

building roof PV would be similar). Photos by Otto VanGeet, NREL

Roof area. The roof is in excellent condition and suitable for a ballasted PV system. The south 

wing has approximately 2,300 ft2 total unshaded area available (Figure 5-7), the east wing has 

approximately 750 ft2 available (Figure 5-8), for an assumed total available area of 

approximately 3,000 ft2

. Using an installed PV power density of 8 W/ft2, up to 24 kW of PV 

could be installed. If the areas are optimized or higher efficiency modules are used, up to 30 kW 

could be installed, which is what is assumed for this study. The existing electrical panel LP2A 

has spaces and capacity for PV breakers (Figure 5-9). The electrical room has adequate room for 

PV inverters (Figure 5-10). 

Figure 5-7. South wing looking west where PV is proposed (left) and looking south (right). Photos 

by Otto VanGeet, NREL 
37 

Figure 5-8. East wing roof looking east is also suitable for PV (left) and typical parapet is 

approximately 28” high (right). Photos by Otto VanGeet, NREL

Figure 5-9. Panel LP2A has many spaces where a PV breaker could be installed (left) and 225 

ampere (A) 480 V Panel LP2A has adequate capacity for PV (right). Photos by Otto VanGeet, NREL

Figure 5-10. Panel LP2A is located in the electrical room near the roof. Photos by Otto VanGeet, 

NREL 

Carport area: The Phoenix Area Office has six large, unshaded carports that should be used for 

PV (Figure 5-11 and Figure 5-12). The two northeast-most carports have an existing SRP PV 

system. Each carport is 18 ft × 140 ft (2,520 ft2 each), so the available area is 15,120 ft2, which is 
38 

enough for 120 kW at 8 W/ft2

. The carport area is the best location for PV because there are no 

issues with roof warranties, potential roof leaks, etc. There is a minor concern about possible 

vandalism from people throwing rocks on the east-most carports. 

Figure 5-11. Existing carports looking southeast (left) and looking northeast (note existing PV on 

east-most carports) (right). Photos by Otto VanGeet, NREL

Figure 5-12. Northwest carports looking northwest (left) and carport structure, which would 

require the attachment of PV support racking (right). Photos by Otto VanGeet, NREL
39 

Figure 5-13. Solmetric SunEye used to measure solar access (all recommended areas have 

excellent solar access)

Source: Images generated by Otto VanGeet, NREL

Another good option to consider is concentrating PV (CPV), which uses optics to concentrate 

sunlight on high efficiency PV cells. Solfocus11 has a manufacturing plant in Mesa, Arizona, and 

could be contacted by Reclamation for a possible highly visible demonstration project at the 

Phoenix Area Office. There are several other good CPV manufacturers that could also be 

 

11 For more information about Solfocus, see http://www.solfocus.com/en/.
40 

considered, but they do not have Phoenix area manufacturing facilities. The southwest corner of 

the site behind the southeast sidewalk and the picnic area north of the building are all excellent 

highly visible locations (Figure 5-14 and Figure 5-15).

Figure 5-14. Possible CPV location behind center light post (which would need to be removed)

(left) and close up of area (right). Photos by Otto VanGeet, NREL

Figure 5-15. Possible CPV locations at southwest corner of site (left) and behind southeast 

sidewalk (right). Photos by Otto VanGeet, NREL

5.5 Economics and Performance

5.5.1 Assumptions and Input Data for Analysis

For this analysis, the following input data were used. The prices used include the PV array and 

the balance of system components for each system, including the inverter and electrical 

equipment, and installation. The economics of grid-tied PV depend on incentives, the cost and 

rate structure of electricity, and the solar resource, including panel tilt and orientation.

A system DC-to-AC conversion of 82% was assumed. This includes losses in the inverter, wire 

losses, PV module losses, and temperature effects, etc. Figure 5-16 summarizes average system 

installation costs for grid-tied U.S. PV systems in 2010 and 2011; the costs have dropped since 

June 2011—an installed cost of $5/W is assumed. For the economic analysis, an annual O&M 

cost of 0.17% of total installed cost is used based on O&M costs of other fixed-axis grid-tied PV 

systems.
41 

Figure 5-16. PV costs

Source: Ryan Wiser, Lawrence Berkeley National Laboratory12

5.5.2 Other Incentives and Financing Opportunities

The Database for State Incentives for Renewable Energy (DSIRE)13 provides a summary of net 

metering, interconnection, and incentives available to customers. The utility for the site is SRP. 

Net-metering agreement—SRP net metering is available to customers who generate electricity 

using PV, geothermal, or wind systems up to 100 kW in AC peak capacity. 

The kilowatt-hours delivered to SRP shall be subtracted from the kilowatt-hours delivered from 

SRP for each billing cycle. If the kilowatt-hours calculation is net positive for the billing cycle, 

SRP will bill the net kilowatt-hours to the customer under the applicable price plan (Standard 

Price Plan E-21, E-23, E-26, E-32, E-36, E-47, E-48, E-61, E-63, E-65, and E-66) for which they 

take service. If the kilowatt-hours calculation is net negative for the billing cycle, SRP will carry 

forward and credit the kilowatt-hours against customer kilowatt-hours usage on the next monthly 

bill. However, if the kilowatt-hours are net negative at the end of the April billing cycle, SRP 

will credit the net kilowatt-hours from the customer at an average annual market price. No 

credits will be carried forward to the May billing cycle.

Interconnection—In June 2007, the Arizona Corporation Commission (ACC) initiated a 

rulemaking process to establish statewide interconnection standards for distributed generation 

(DG). This proceeding is still in progress. Until the new official rules go into effect, the 

commission has recommended that the utilities use the Interconnection Document14 as a guide. 

This document applies to systems up to 10 MW in capacity. 

The state’s utilities independently developed interconnection agreements for DG prior to the 

ACC’s ongoing proceeding to establish statewide standards. The SRP, which is not regulated by 

 

12 Wiser, R., et al. Tracking the Sun II. Berkeley, CA: Environmental Energy Technology Division, Lawrence 

Berkeley National Laboratory, 2011.

13 For more information on DSIRE, see www.dsireusa.org. 14 Interconnection of Distributed Generation Facilities in the Generic Investigation of Distributed Generation. 

Arizona Corporation Commission. (June 2007). http://images.edocket.azcc.gov/docketpdf/0000074361.pdf. 
42 

the ACC on utility matters, developed DG interconnection guidelines and an interconnection 

agreement based on draft rules and a report released by the ACC in 1999 and 2000, 

respectively15. SRP’s rules include technical protection requirements, a flow chart of 

interconnection procedures, and a two-page interconnection application. The rules establish 

separate requirements for units based on system capacity: 

• Class I: 50 kW or less, single or three-phase 

• Class II: 51 kW to 300 kW, three-phase

• Class III: 301 kW to 5 MW, three-phase 

• Class IV: greater than 5 MW, three-phase. 

SRP’s EarthWise Solar Energy Program provides incentives to its residential and commercial 

customers to purchase PV or solar water-heating systems. In exchange for the incentives, SRP 

will receive all the renewable energy credits (RECs) associated with the systems. SRP’s board of 

directors set a voluntary goal in 2004 of having 15% of their retail sales come from renewable 

resources by 2025, mirroring the renewable energy standard that other Arizona utilities are 

required to meet. The RECs that SRP receives through the EarthWise program will help the 

utility meet this goal. Note that if Reclamation sells the RECs and wants to take credit for the 

solar system, Reclamation would need to buy replacement RECs.

As of June 28, 2011, small commercial PV systems (30 kW and smaller) can receive a one-time 

incentive of $1.35/watt DC, up to a maximum of $40,500. The budget for larger commercial PV 

systems (30 kW to 600 kW) is currently exhausted16. SRP has funding for a total of 1.1 MW of 

small commercial PV systems and 6 MW of large PV systems through April 30, 2012. PV 

incentives are scheduled to step down twice during this time period as certain MW levels are 

installed17.As of August 2011, funding set aside for production-based incentives for PV systems 

larger than 30 kW has been exhausted through April 30, 2012. SRP will, however, honor 

applications that have already been awarded an incentive reservation. SRP will also accept an 

additional 2 MW of applications in the event a previously approved project is cancelled. See the 

listed website above for updated information.

There are several options for getting a solar PV system financed. The best option is to obtain 

agency appropriations, which is analyzed in detail below. One potentially plausible financing 

option is third-party ownership. The agreement works by having a solar contractor install, 

finance, and operate the system while the customer (Reclamation) purchases the electricity 

generated by the system. This arrangement is called a power purchase agreement (PPA)18. 

 

15 For more information on SRP interconnection requirements, see 

http://www.srpnet.com/electric/Generators.aspx?res. 16 For details, see http://www.srpnet.com/electric/Generators.aspx?res. 17 For more information on PV incentives in Arizona, see

http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=AZ11F&re=1&ee=1. 18 For more information on PPAs, see 

http://www1.eere.energy.gov/femp/financing/power_purchase_agreements.html. 
43 

A solar lease agreement is another option that could be considered. If the PV system is owned by 

a private tax-paying entity, this entity can qualify for a 30% federal tax credit and accelerated 

depreciation on the PV system, which is worth about 15%. The total potential tax benefits to the 

tax-paying entity are about 45% of the system cost. Because state and federal governments do 

not pay taxes, private ownership of the PV system would be required to capture tax incentives. In 

this configuration, the land or roof area that the solar system is on would need to be leased to the 

owner of the system for the duration of the contract. Because of the high transaction costs of a 

PPA, only large PV systems should be considered. By combining carport (120 kW), roof (30 

kW), and ground-mounted CPV (100 kW), at least 200 kW of PV could be installed, which is 

large enough for a PPA. A possible method to install smaller (< 90 kW) systems under a PPA 

would be to aggregate the installation of PV systems at several installations under one contract. 

5.5.3 Data and Assumptions

Because the PV system size preferred by Reclamation is unknown, NREL assumed a 30 kW PV 

system; because of economies of scale, a large system will have lower costs and better 

economics. However, no incentives currently exist for larger systems. If incentives for larger 

systems become available again, NREL could analyze the economics based on the incentives. 

5.5.4 Performance and Savings Results

A 30-kW system will generate approximately 48,600 kWh per year, offsetting approximately 5% 

of the Reclamation Phoenix Area Office annual electrical energy needs. The system would cost 

approximately $111,000 after the SRP incentive of $39,000. The payback would be marginal at 

27 years. By including the carports (120 kW) with the rooftop system (30 kW), a 150 kW system 

could be installed that would generate approximately 243,000 kWh per year, offsetting 

approximately 27% of the Reclamation Phoenix Area Office’s annual electrical energy needs. If 

incentives for larger systems become available again, a PPA would be feasible (150 kW and 

larger) and would be recommended. If CPV is installed, the savings would be even larger. 
44 

Table 5-2. PV Economics–Phoenix Area Office

Tie-in 

Location

Array 

Tilt (°)

Area 

Reqd 

(ft2)

PV 

System 

Size 

(kW)

Annual 

Output 

(kWh/yr)

Annual 

Cost 

Savings 

($/yr)

Annual 

O&M 

($/yr)

Annual 

Cost 

Savings 

After 

O&M 

($/yr)

System 

Cost With 

No 

Incentives 

($)

Payback 

Period 

With No 

Incentive 

(years)

SRP 

Incentive 

$1.35/W 

DC 

capped 

at 

$40,500

Cost After 

Incentives 

($)

Payback 

Period 

After 

SRP 

Incentive 

(years)

System 

Cost After 

Federal 

(45%) and 

SRP 

Incentives 

($)

Payback 

Period 

After 

SRP and 

Federal 

Incentive 

(years)

BOR Phoenix Area Office = 892,800 kWh annual

Roof 

mounted 10 3,750 30 48,600 4,374 255 4,119 150,000 36 39,000 111,000 27 61,050 15

Carport 

mounted 10 3,750 30 48,600 4,374 255 4,119 150,000 36 39,000 111,000 27 61,050 15

Maximum Carport PV

Carport 

mounted 10 15,120 121 195,955 17,636 1,028 16,608 604,800 36 40,500 564,300 34 310,365 19

Note: Federal tax incentives are only available for taxpaying entities.
45 

5.6 Facility-Scale Conclusions and Recommendations

Reclamation’s Phoenix Area Office in Glendale, Arizona, which is considered for a solar PV 

system in this report, has many near-ideal areas in which to implement a PV system. If 

Reclamation proceeds with this type of installation, it is recommended that Reclamation contact 

SRP and reserve incentives for a 30 kW DC system (or other size, as determined by 

Reclamation). If incentives for larger systems become available again, a larger system should be 

installed. When the system goes out to bid, a design-build contract should be issued that requests 

the best performance (in kWh/yr) at the best price, letting the vendors optimize the system 

configuration, including racking, slope, modules, etc. Because of the high cost of energy, 

dropping cost of PV, excellent solar resource, and excellent incentives, a government-owned PV 

system provides a reasonable payback, is easy to implement, and is therefore recommended. If 

funding is not available, then a third-party PPA is the most plausible way for a system to be 

financed on this site. 
46 

6 Facility-Scale Assessments of Willows Office and 

Lake Berryessa Facility 

On June 21, 2012, a team led by NREL together with Reclamation personnel conducted an 

assessment of Reclamation’s Willows Office building and the Lake Berryessa site. During the 

site visit, the team identified several suitable locations for grid-connected PV. 

6.1 Willows Office

6.1.1 Willows Office—Facility Overview

Reclamation’s Willows Office building is located at 1140 W. Wood St., Willows, CA 95988. 

The structure is a single-story wood frame office building with roof-mounted mechanical

equipment. The building faces south, with the main entry on the north side. An aerial image of 

the building is shown in Figure 6-1. Figure 6-2 shows elevation views, and a site plan is shown 

in Figure 6-3. 

The building has a composite shingle sloped roof. The roof is in excellent condition. The south 

facing roof has an existing PV array that annually generates approximately 12,000 kWh. Figure 

6-4 shows photos of the existing PV array and inverters.

The Willows Office is connected to Pacific Gas and Electric Company (PG&E) electric utility.

The electric tariff is “A1–Small General Service”19

, which is complex time of use (TOU) energy

(kWh) only (no demand charges) and minimal monthly service charges. The rate has a summer

(May 1 to October 31) week day on-peak, partial-peak, and off-peak rate, and a winter partialpeak and off-peak rate. The rate is very favorable for PV systems because the highest rates are 

mid-day during the summer when PV output is at its maximum. The annual electrical energy use 

was 125,520 kWh in FY 2011, and the average rate during FY 2011 was $0.17/kWh. 

19 For details regarding the A1-Small General Service electric rate, see 

http://www.pge.com/tariffs/tm2/pdf/ELEC_SCHEDS_A-1.pdf. 
47 

Figure 6-1. Aerial view of Willows Office 

Source: Google Earth image provided by Reclamation

Figure 6-2. Willows Office entrance and north elevation view (left), and Willows Office northeast 

view (right). Photos by Otto VanGeet, NREL
48 

Figure 6-3. Site plan of Willows Office

Figure 6-4. Existing inverters and PV system at Willows Office. Photos by Otto VanGeet, NREL

6.1.2 Willows Office—PV Performance

The PV arrays must be installed in unshaded locations on the ground or on building roofs that 

have an expected life of at least 25 years. The proposed site has excellent annual solar access. 

The predicted array performance was found using PVWatts Version 2 for Willows, a 
49 

performance calculator for grid-connected PV systems created by NREL’s Renewable Resources 

Data Center.20

Table 6-1. Annual AC Energy and Cost Savings Results in kWh/kW for South-Facing, 5-DegreeSloping, Fixed-Tilt PV from PVWatts for Willows (Carport PV)

City: Willows

State: California

Latitude: 39.3° N

Longitude: 122.3° W

Elevation: 42 m

PV System Specifications

DC Rating: 1.0 kW

DC to AC Derate Factor: 0.820

AC Rating: 0.8 kW

Array Type: Fixed Tilt 

Array Tilt: 5.0°

Array Azimuth: 180.0°

Energy Specifications

Cost of Electricity: 17.0 ¢/kWh

Results

Month 

Solar 

Radiation

(kWh/m2/day)

AC 

Energy 

(kWh)

Energy 

Value

($)

1 2.25 52 8.84

2 3.39 74 12.58

3 4.35 104 17.68

4 5.76 132 22.44

5 6.82 158 26.86

6 7.46 162 27.54

7 7.78 173 29.41

8 7.06 158 26.86

9 5.86 127 21.76

10 4.25 98 16.66

11 2.71 60 10.20

12 2.14 49 8.33

Year 4.99 1348 229.16

Figure 6-5. Proposed PV system locations at Reclamation’s Willows building (highlighted in blue) 

Willow’s staff indicate the carport is not feasible at this time due to operational space 

requirements. Source: Google Earth (modified by Otto VanGeet, NREL)

 

20 For more information on NREL’s PVWatts Version 2, see http://www.nrel.gov/rredc/pvwatts/grid.html. 
50 

The rooftop area and carports designated for PV installations have excellent solar exposure (see 

Figure 6-5) and few existing obstructions. The north and west roofs have too much shading for 

PV.

6.1.3 Willows Office—Potential PV System Locations 

Roof area. The roof is asphalt composite shingles in excellent condition and suitable for a direct 

attached PV system similar to the existing system. The east roof (Area 1) is sloped to the east at 

5/12 (23 degrees) and has approximately 967 ft2 total unshaded area available (Figure 6-7). 

Using an installed PV power density of 10 W/ft2, up to 10 kW of PV could be installed. If higher 

efficiency modules with power density of 15 W/ft2are used, up to 15 kW could be installed (this 

is assumed for this study). From PVWatts, the annual PV production of an east-facing roof that 

slopes at 23 degrees is 1,226 kWh/kW. 

The south-facing courtyard roof (Area 2) is sloped to the south at 3/12 (14 degrees) and has 

approximately 1,373 ft2 total area available that is currently shaded by courtyard trees (Figure 6-

8) PV could not be installed on Area 2 without significant trimming or removal of existing trees. 

From PVWatts, the annual PV production of a south-facing roof sloped at 14 degrees is 1,426 

kWh/kW. Using an installed PV power density of 10 W/ft2, up to 14 kW of PV could be 

installed. If higher efficiency modules with a power density of 15 W/ft2

 are used, up to 20 kW 

could be installed (this is assumed for this study). 

The existing electrical panel LP2A has spaces and capacity for PV breakers (Figure 6-6). The 

outside of the building has adequate room for additional PV inverters similar to the existing 

installation.

Figure 6-6. Existing PV system electrical breaker subpanel (left) and right building main 240 V, 600 

A electrical panel with spaces for future solar breakers. Photos by Otto VanGeet, NREL
51 

Figure 6-7. East roof of Willow building looking north (Area 1) (left), and east side of building and 

roof looking northwest (right). Photos by Otto VanGeet, NREL

Figure 6-8. South-facing courtyard roof of Willow building looking west (Area 2) (left) and southfacing courtyard roof looking north from courtyard (right). Photos by Otto VanGeet, NREL

Carport area: The east and south parking lots areas have a total unshaded area of approximately 

22,533 ft2

, which is enough for up to 220 kW at 10 W/ft2. From PVWatts (see Table 6-1), the 

annual PV production of a south-facing roof sloped at 5 degrees is 1,348 kWh/kW. A 93 kW PV 

system would have an annual output of 125,364 kWh, which would make the office net-zero 

electrical annual energy. The assumed size of the carport that would be installed is 93 kW. A 

carport PV system would be a nice amenity in the hot sunny Willows area; however, Willow’s 

staff indicates the carport is not feasible at this time due to operational space requirements.
52 

Figure 6-9. PV-covered carports could be installed over parking lot: (clockwise from upper left) 

looking northeast, looking east, east edge looking north (notice shade from trees defines east

boundary), and looking southeast. Willow’s staff indicates the carport is not feasible at this time 

due to operational space requirements. Photos by Otto VanGeet, NREL

6.2 Lake Berryessa Office 

6.2.1 Lake Berryessa Office—Facility Overview 

Reclamation’s Lake Berryessa Office is located at 5520 Knoxville Road, Napa, CA 94558. 

The Lake Berryessa Office is connected to PG&E electric utility. The electric tariff is “A1–Small 

General Service”21, which is a complex Time Of Use (TOU), energy (kWh) only (no demand 

charges) rate with minimal monthly service charges. The rate has a summer (May 1 to October 

31) week day on- peak, partial-peak, and off-peak rate, and a winter partial-peak and off-peak

rate. The rate is very favorable for PV systems because the highest rates are mid-day during the

summer when PV output is at its maximum. The annual electrical energy use was 182,080 kWh

in FY 2011, and the average rate during FY 2011 was $0.15/kWh.

21. For details regarding the A1-Small General Service electric rate, see

http://www.pge.com/tariffs/tm2/pdf/ELEC_SCHEDS_A-1.pdf.
53 

Figure 6-10. Aerial view of Lake Berryessa

Office Source: Google Earth image provided by 

Reclamation 

Figure 6-11. Existing PV system and inverters at Lake Berryessa Office (existing PV 1). Photos 

by Otto VanGeet, NREL 
54 

Figure 6-12. Second existing PV system and inverters at Lake Berryessa Office (existing PV 

2). Photos by Otto VanGeet, NREL

6.2.2 Lake Berryessa—PV Performance 

The PV arrays must be installed in unshaded locations on the ground or on building roofs that 

have an expected life of at least 25 years. The proposed ground-mounted and carport PV sites 

have excellent annual solar access. The predicted array performance was found using 

PVWatts Version 2 for Lake Berryessa, a performance calculator for grid-connected PV 

systems created by NREL’s Renewable Resources Data Center.22

Table 6-2. Annual AC Energy and Cost Savings Results in kWh/kW for South-Facing, 5-

Degree, Fixed-Tilt PV from PVWatts for Lake Berryessa

City: Napa

State: California

Latitude: 38.3° N

Longitude: 122.3° W

Elevation: 227 m

PV System Specifications

DC Rating: 1.0 kW

DC to AC Derate Factor: 0.820

AC Rating: 0.82 kW

Array Type: Fixed Tilt 

Array Tilt: 5.0°

Array Azimuth: 180.0°

Energy Specifications

Cost of Electricity: 15.0 ¢/kWh

Results

Month 

Solar 

Radiation

(kWh/m2/day)

AC 

Energy 

(kWh)

Energy 

Value

($)

1 2.47 57 8.55

2 3.57 77 11.55

3 4.61 111 16.65

4 6.10 140 21.00

5 7.04 168 25.20

6 7.73 174 26.10

7 7.77 179 26.85

8 6.84 158 23.70

9 5.91 132 19.80

10 4.38 101 15.15

11 2.97 66 9.90

12 2.29 53 7.95

Year 5.15 1717 212.55

22. For more information on NREL’s PVWatts Version 2, see http://www.nrel.gov/rredc/pvwatts/grid.html.
55 

Figure 6-13. Proposed PV system locations at Reclamation’s Lake Berryessa site (highlighted in 

blue) 

Source: Google Earth (modified by Otto VanGeet, NREL) 

6.2.3 Lake Berryessa Office—Potential PV System Locations 

It would be difficult to install PV on the tile rooftop area so only ground-mount and carports PV 

installations are considered. All are nearly flat, have excellent solar exposure (see Figure 6-13), 

and few existing obstructions. Photographs of potential ground mount and carport locations are 

shown in Figures 6-14 to 6-17. Lake Berryessa staff indicates PV Carport Area 1 and the south 

half of PV Carport Area 2 are not feasible at this time because of operational space 

requirements. 

Figure 6-14. PV Area 1 looking west (note existing PV 1 near sidewalk in distance) (left) and east 

side of PV Area 1 looking northeast (right). Photos by Otto VanGeet, NREL
56 

 Figure 6-15. PV Area 2 beyond fence looking north (left) and PV Area 3 looking northeast (right). 

Photos by Otto VanGeet, NREL

Figure 6-16. PV Carport Area 1: looking southeast (left) and looking north (right)-Lake 

Berryessa staff indicates PV Carport Area 1 is not feasible at this time because of operational 

space requirements. Photos by Otto VanGeet, NREL 

Figure 6-17. PV Carport Area 2: looking northeast (left), and main meter and electrical panel 

that serves south buildings at Lake Berryessa and possible PV tie in location (right). Photos by 

Otto VanGeet, NREL 
57 

6.3 Facility-Scale PV Systems

The amount of energy produced by a PV panel depends on several factors, including type of 

collector, tilt and azimuth of the collector, temperature, level of sunlight, and weather conditions. 

An inverter is required to convert DC to AC of the desired voltage compatible with building and 

utility power systems. The balance of the system consists of conductors/conduits, switches, 

disconnects, and fuses. Grid-connected PV systems feed power into the facility’s electrical 

system and do not include batteries. Section 2 Solar Technology Overview provides additional 

detail on the major components and functioning of PV systems. 

PV panels are very sensitive to shading. When shade falls on a panel, that portion of the panel is 

no longer able to collect the high energy beam radiation from the sun. PV panels are made up of 

many individual cells that each produce a small amount of current and voltage. These individual 

cells are connected in series to produce a larger current. If an individual cell is shaded, it will act 

as a resistance to the whole series circuit, impeding current flow and dissipating power rather 

than producing it. By estimating the amount of shading, the NREL team can determine whether 

the area is appropriate for solar panels. 

If a site is found to have good potential for a PV system, the next step is to determine the size of 

that system. This is highly dependent on the average energy use of the facilities on the site. It is 

generally not advisable to provide more power than the site will use due to the economics of 

most net-metering agreements. 

PV systems have the following components: 

• PV arrays that convert light energy to DC electricity

• Inverters that convert DC to AC, and provide important safety, monitoring, and control 

functions 

• Various wiring, mounting hardware, and combiner boxes 

• Monitoring equipment. 

6.4 Economics and Performance

6.4.1 Assumptions and Input Data for Analysis

For this analysis, the following input data were used. The prices used include the PV array and 

the balance of system components for each system, including the inverter and electrical 

equipment, and installation. The economics of grid-tied PV depend on incentives, the cost and 

rate structure of electricity, and the solar resource, including panel tilt and orientation.

A system DC-to-AC conversion of 82% was assumed. This includes losses in the inverter, wire 

losses, PV module losses, and temperature effects, etc. Figure 6-18 summarizes average system 

installation costs for grid-tied U.S. PV systems in 2010 and 2011; the costs have dropped since 

June 2011—an installed cost of $5/W is assumed for roof- and ground-mounted PV, and 

$5.50/W for carport PV. 
58 

Figure 6-18. PV costs

Source: Ryan Wiser, Lawrence Berkeley National Laboratory23

6.4.2 Other Incentives and Financing Opportunities

DSIRE24 provides a summary of net metering, interconnection, and incentives available to 

customers. The utility for both sites is PG&E.

Expected performance-based buydowns for systems under 30 kW—Began in 2007 at 

$2.50/W AC for residential and commercial systems (adjusted based on expected performance) 

and $3.25/W AC for government entities and nonprofits (adjusted based on expected 

performance). The incentive levels decline as the aggregate capacity of PV installations 

increases. Incentives will be awarded as a one-time, up-front payment based on expected 

performance, which is calculated using equipment ratings and installation factors such as 

geographic location, tilt, orientation, and shading. At the time of writing this report the PG&E 

incentive was in “step 10,” which provides $0.70/W if the system is owned by the government. 

Performance-based incentives (PBI) for systems 30 kW and larger—Began in 2007 at 

$0.39/kWh for the first five years for taxable entities, and $0.50/kWh for the first five years for 

government entities and nonprofits. The incentive levels decline as the aggregate capacity of PV 

installations increases. PBI will be paid monthly based on the actual amount of energy produced 

for a period of five years. At the time of writing this report, the PG&E incentive was in “step 10” 

which provides $0.025/kWh for commercial (if system is owned by a third party) or $0.088/kWh 

if the system is owned by the government25.

Net Metering Agreement—California’s net-metering law, which took effect in 1996, requires 

all utilities to offer net metering to all customers for solar energy systems up to 1 MW. Net 

excess generation (NEG) is carried forward to a customer's next bill. Under prior law, any NEG 

remaining at the end of each 12-month period was granted to the customer's utility. AB 920 of 

2009 gave customers two additional options for the NEG remaining after a 12-month period— 

customers have the option of rolling over any remaining NEG month to month indefinitely, or 

they can receive financial compensation from their utility for the remaining NEG. The California 

 

23 Wiser, R., et al. Tracking the Sun IV. Berkeley, CA: Environmental Energy Technology Division, Lawrence 

Berkeley National Laboratory, 2011.

24 For more information on DSIRE, see www.dsireusa.org. 25 Current incentives can be found at http://www.csi-trigger.com/. 
59 

Public Utilities Commission (CPUC) set the compensation rate at the 12-month average spot 

market price for the hours of 7 a.m. to 5 p.m. for the year in which the surplus power was 

generated. 

Publicly owned utilities may elect to provide coenergy metering, which is the same as net

metering, but incorporates a time-of-use rate schedule. Customer-generators with systems sized

between 10 kW and 1 MW who are subject to time-of-use rates are entitled to deliver electricity

back to the system for the same time-of-use (including real-time) price that they pay for power 

purchases. However, time-of-use customers who choose to coenergy meter must pay for the 

metering equipment capable of making such measurements. Customer-generators retain

ownership of all RECs associated with the generation of electricity they use on site26. 

Interconnection—Nonexporting systems (sized and designed so that the electricity is only used 

on-site and will never deliver electricity to the grid) and all net metered systems, regardless of

nameplate capacity, can qualify for the fast track process. After a customer applies for

interconnection, the utility performs an initial review. If the applicant passes through initial 

review screen A through M, the system will be able to interconnect without a supplemental 

review. There is no interconnection size limit. The CPUC has explicitly ruled that technologies 

eligible for net metering (up to 1 MW) are exempt from interconnection application fees, as well 

as from initial and supplemental interconnection review fees.

There are several options for getting a solar PV system financed. The best option is to obtain 

agency appropriations, which is analyzed in detail below. One potentially plausible financing 

option is third-party ownership. The agreement works by having a solar contractor install, 

finance, and operate the system while the customer (Reclamation) purchases the electricity

generated by the system. This arrangement is called a PPA27

. 

A solar lease agreement is another option that could be considered. If the PV system is owned by 

a private tax-paying entity, this entity can qualify for a 30% federal tax credit and accelerated 

depreciation on the PV system, which is worth about 15%. The total potential tax benefits to the 

tax-paying entity are about 45% of the system cost. Because state and federal governments do

not pay taxes, private ownership of the PV system would be required to capture tax incentives. In 

this configuration, the land or roof area that the solar system is on would need to be leased to the 

owner of the system for the duration of the contract. Because of the high transaction costs of a 

PPA, only large PV systems (90 kW+) should be considered. 

6.4.3 Data and Assumptions

Because the PV system size preferred by Reclamation is unknown, NREL analyzed each

possible PV system individually. 

6.4.4 Performance and Savings Results 

PV performs well in the sunny Willows and Lake Berryessa offices. The California Solar 

Incentives (CSI) and falling PV prices lead to payback times of 21 to 24 years depending on 

location and system type (see Table 6-3). Carport PV systems have an approximately 2-year 

longer payback time because of the added structure cost for the carport but would provide a nice 

26. For additional information on PG&E net metering see

http://www.pge.com/b2b/newgenerator/netenergymetering/. 27 For more information on PPAs, see

http://www1.eere.energy.gov/femp/financing/power_purchase_agreements.html.
60 

amenity in the hot sunny locations. Both office could become net-zero annual electrical energy

by installing 93 kW of PV at Willows (would require a carport system that Willow staff has 

indicated could not be built at this time because of operational space requirements) or 128 kW 

at Lake Berryessa. If these large systems are installed, a PPA could be considered that would 

bring the payback down to about 16 years. 

A possible method to install smaller (< 90 kW) systems under a PPA would be to aggregate the 

installation of PV systems at several installations under one contract.
61 

Table 6-3. PV Economics

Tie-In

Location

Array 

Tilt 

(°)

Area 

Available 

(ft2)

PV 

System

Size 

(kW)

Annual 

Output 

kWh/yr

Annual Cost 

Savings ($/yr)

Annual 

O&M 

($/yr)

Annual 

Cost 

Savings 

After 

O&M 

($/yr)

Total 

System 

Cost With 

No 

Incentives 

($)

Payback 

Period 

With No 

Incentive 

(yr)

CSI 

Incentive 

$0.7/W AC 

or Over 30 

kW 

$0.088/kWh 

for 5 years

Cost 

After 

incentives 

($)

Payback 

Period 

After CSI 

Incentive 

(yr)

System Cost 

After Federal 

(45%) and CSI 

Incentives($) 

of $0.025/kWH 

for 5 years

Payback 

Period 

After 

PG&E

and 

Federal 

Incentive 

(yr)

BOR Willows Office = 125,520 kWh annual

East 

Roof 

Area 1 23 967 15 18,390 3,126 128 2,999 75,000 25 8,400 66,600 22 NA NA

South 

Roof 

Area 2 14 1,373 20 28,520 4,848 187 4,661 110,000 24 11,200 98,800 21 NA NA

Max. Carport PV

Carport 

Mounted 5 22,533 93 125,364 21,312 870 20,442 511,500 25 55,160 456,340 22 297,498 15

BOR Lake Berryessa Office = 182,080 kWh annual 

Area 1 5 5,431 54 76,957 11,544 462 11,082 271,550 25 30,414 241,136 22 162,930 15

Area 2 5 1,200 12 17,004 2,551 102 2,449 60,000 25 6,720 53,280 22 36,000 15

Area 3 5 6,684 67 94,712 14,207 568 13,639 334,200 25 37,430 296,770 22 200,520 15

Max. Carport PV

Carport 

1 5 8,270 83 117,186 17,578 773 16,805 454,850 27 51,562 403,288 24 264,121 16

Carport 

2 5 5,532 55 78,388 11,758 517 11,241 304,260 27 34,491 269,769 24 176,677 16

Notes: (1) Federal tax incentives are only available for taxpaying entities. (2) Willow staff indicated the carport could not be built at this time because of 

operational space requirements. (3) Lake Berryessa staff indicated PV Carport Area 1 and the south half of PV Carport Area 2 could not be built at this time 

because of operational space requirements. 
62 

6.5 Facility-Scale Conclusions and Recommendations 

Reclamation’s Willows and Lake Berryessa offices in California considered for a solar PV 

system in this report have many good areas in which to implement a PV system. It is 

recommended that Reclamation consider installing PV at these offices while PG&E incentives 

under CSI exist. When the system goes out to bid, a design-build contract should be issued 

requesting the best performance (in kWh/yr) at the best price, letting the vendors optimize the 

system configuration, including racking, slope, modules, etc. Because of the high cost of energy, 

dropping cost of PV, good solar resource, and fair incentives, a government-owned PV system 

provides a marginal payback, is easy to implement, and is therefore worth considering. If

funding is not available and a 90+ kW system is desired, then a third-party PPA is the most 

plausible way for a system to be financed on this site. A possible method to install smaller (< 90

kW) systems under a PPA would be to aggregate the installation of PV systems at several

installations under one contract. 
63 

7 Utility-Scale Assessment of Pumping Plants Along 

the Central Arizona Project

On Aug. 29, 2011, a team from NREL, Reclamation, and the BLM conducted visits to three sites 

to assess Reclamation-owned lands for potential utility-scale solar energy power plant 

development. The sites were previously identified by Reclamation through a screening and 

ranking analysis conducted by staff from Reclamation Phoenix Area Office.

28

7.1 Site Assessments

All three sites were north of Reclamation’s Hayden-Rhodes Aqueduct right-of-way. The sites 

were located: 1) east of Little Harquahala Pumping Station (La Paz and Maricopa County site), 

2) at Belmont Mountain, and 3) east of Hassayampa Pumping Station.

Site 1. The site is a 300-plus acre site east of the Little Harquahala Pumping Station on the 

western end of La Paz and Maricopa Counties; the site has an acceptable slope (≤ 3%) and a 

reasonable amount of mesquite vegetation to remove for a CSP or PV plant of 50–60 MW (see 

Figure 7-1 and Figure 7-2). 

Figure 7-1. High potential solar site east of Little Harquahala Pumping Station 

Source: Google Earth

 

28 Reclamation’s Science and Technologies Project ID 8343, “Renewable Power Generation for Water 

Transmission” study identified in the GIS analysis entitled “Renewable Energy Suitability Analysis for the Central 

Arizona Project Canal System.” 
64 

Figure 7-2. View of site 1 looking north from northern edge of CAP. Photo by Scott Haase, NREL

Site 2. The Belmont Mountain site is located on Avenue 395 near Tonopah, Arizona. The site is 

covered with mounds and outcroppings of saguaro cactus, which would require significant 

grading, etc. for removal of cactus and construction of a CSP or PV plant. An environmental 

assessment will be required at this particular location; therefore, this site was not considered 

reasonable for solar development. Also, the road to the site, which is about 4 miles, would 

require major improvement to handle the large vehicles used for material delivery. In addition,

there are no power transmission lines running through or adjacent to the site although there is a 

proposed 500 kilovolt (kV) line being considered at this time. This site is not being considered at 

this time, but future study is recommended since transmission may be available, and large 

quantities of BLM land (about 11,000 acres) are adjacent to this site.

Site 3. The site east of the Hassayampa Pumping Station just off the Sun Valley Parkway near 

the Sun City Festival housing development proved to be the best location. It has a slope ≤ 1% 

and little vegetation. The 400-plus acre site could support a utility-scale solar plant up to 60+ 

MW CSP and 60–70 MW PV. It is adjacent to a 500 kV transmission line for interconnection to 

the grid. This interconnection could be used if a feasible offtaker is available and if transmission 

capacity on the line is available. Also, it may be possible to access the 69 kV lines that serve the 

Hassayampa pumping station, with peak load of 58 MW (see Figure 7-3 and Figure 7-4). 
65 

Figure 7-3. High potential solar site east of Hassayampa Pumping Station

Source: Google Earth

Figure 7-4. View looking north at site 3 from northern edge of CAP. Photo by Otto VanGeet, NREL

 
66 

7.2 PV Potential to Meet Hassayampa Pumping Load

Pumping loads at the Hassayampa Pumping Station were analyzed for the potential for PV to 

meet its electrical pumping load. Three different sized PV systems were analyzed: 20 MW, 50 

MW, and 100 MW. 

7.2.1 Electrical Production Analysis

The annual hourly load data for 2010 at the Hassayampa Pumping Station was provided by 

Douglas Crosby, water operations supervisor, CAP. The average load in 2010 was approximately 

33 MW with a peak load of 55 MW. The total annual energy consumption is 288,272 MWh/year. 

The annual average daily load profile is consistently around 30 MW (Figure 7-5). 

Figure 7-5. Annual average daily load profile at Hassayampa

The seasonal load profile is shown in Figure 7-6. The maximum loads occurred in November and 

December 2010, and the minimum loads occurred in July and August. This unusual load pattern 

is due to the requirement to fill Lake Pleasant in the off-peak power demand season and the 

ability to conserve energy during high power demand in the summer season when water is 

released from the reservoir for power generation and water consumption. 

Figure 7-6. Seasonal load profile for Hassayampa

The software optimization tool HOMER was used to analyze a PV grid-tied system with three 

different PV system sizes installed: 20 MW, 50 MW, and 100 MW. The results are summarized

in Table 7-1. The PV system is modeled as a horizontal, continuous adjustment tracking system 

with a lifetime of 25 years and a derating factor of 95%. Note: The tracking algorithm in the 

HOMER model is not identical to the algorithm in the SAM model. To ensure the same annual 

power production from the PV, the derate factor was increased in the HOMER model.
67 

Table 7-1. Electrical Production

Scenario PV Size 

(MW)

Electrical PV 

Production 

(kWh)

Grid 

Purchase 

(kWh)

Grid Sales 

(kWh)

PV Production as 

a Fraction of the 

Load 

Base case 0 N/A 288,269,952 N/A 0%

1 20 47,507,504 245,133,200 4,371,542 16%

2 50 118,768,464 196,803,952 27,303,842 41%

3 100 237,536,928 172,086,144 121,354,960 82%

Figure 7-7 shows the monthly average electric source of power (yellow is power produced from 

PV, and blue is power provided by the grid) for scenario 3, a 100 MW PV system installed to 

meet the Hassayampa electric load.

Figure 7-7. Monthly average electric production (100 MW system)

Figure 7-8 shows the hourly annual PV production (yellow) with a 100 MW system installed at 

Hassayampa. The amount of power sold back to the grid is shown in purple, and the annual 

monthly load demand for Hassayampa is shown in blue. In July, for the scenario of a 100 MW 

PV system, nearly all the power from the PV production could be sold back to the grid because

the load is reduced significantly during this time. Due to the tracking algorithm used in HOMER, 

Figure 7-8 shows somewhat lower peak power production in the summer. Despite the lower 

peak, the actual monthly data in Figure 7-8 shows that the PV energy production is much higher 

in the summer. 
68 

Figure 7-8. Annual hourly PV production at Hassayampa

7.2.2 Economics

NREL analyzed the economics of the three different sized PV systems tied to the grid to meet the 

pumping load at Hassayampa. The capital cost for PV is modeled at $3/W and $2.50/W for 

replacement cost. The O&M cost for PV is assumed to be 0.1% of the capital cost annually. The 

price to purchase power from the grid was estimated to be $0.035/kWh, and the demand price for 

sellback was modeled at $0.10/kWh. The annual real interest rate was assumed to be 6% for a 

project lifetime of 25 years (life of the PV system). Table 7-2 summarizes the capital cost of the 

PV system, the annual operating cost, total net present cost, and LCOE. In scenario 3 (100-MW 

PV system installed), the PV system produces more power annually than is consumed by the 

Hassayampa load and thus the annual overall purchase cost from the grid is negative. CAP could 

receive approximately $5.8 million annually in excess power sold back. 

Table 7-2. Comparison of Grid Cost with PV Sizes

Scenario PV 

Size

(MW)

Capital Cost 

for PV

($)

Operating 

Cost

($/yr)

Total Net 

Present 

Cost

($)

LCOE

($/kWh)

Base case 0 N/A 10,089,448 128,977,008 0.035

1 20 60,000,000 8,202,507 164,855,568 0.044

2 50 141,000,000 4,298,754 195,952,512 0.049

3 100 286,000,000 -5,826,480 211,518,016 0.058
69 

NREL performed a sensitivity analysis that assumed the cost to purchase power from the grid 

will increase to see at what cost the PV systems would be economically viable. We modeled 

several grid power prices ranging from $0.035/kWh to $0.35/kWh. The assumed sell-back price 

to the grid remained the same at $0.10/kWh. The capital cost of the PV system also remained the 

same. The analysis indicates that PV becomes cost-effective when grid power prices rise above 

$0.09/kWh, with a 100 MW PV system being the most cost-effective solution when power prices 

are $0.11/kWh or greater. The graph in Figure 7-9 illustrates the optimal capacity size of the PV 

system (y-axis) as a function of the price of power (x-axis).

Figure 7-9. Sensitivity analysis on increase price of power 

7.3 Technology Description

Most commercial CSP systems to date are parabolic trough systems that reflect and focus 

sunlight onto a linear receiver tube. The receiver contains a high-temperature fluid that is heated 

by sunlight and then used through a heat exchanger with water to produce superheated steam that 

drives the turbine generator. The parabolic trough CSP technology has been in commercial 

operation in southern California since 1981 (nine plants with a total of 350 MW). The latest CSP 

trough plant in southern Nevada, Nevada Solar One (64 MW), came on line in 2009. 

Photovoltaics are semiconductor devices that convert sunlight directly into electricity. They do 

so without any moving parts and without generating any noise or pollution. They must be 

mounted in unshaded locations— rooftops, carports and ground-mounted arrays are common 

mounting locations. PV systems work well in the sunny Phoenix area. 

The typical choices are south-facing (0° azimuth) rows of fixed panels tilted at latitude or singleaxis modules oriented north-south that tilt from east to west during the day to track the sun. 

Single-axis tracking PV systems use 10% more land to mitigate adjacent panel shading; 

however, the cost increase over fixed panels is small (10%) and the system produces up to 35% 

more electrical energy. 

Current private-sector development on BLM lands shows a major trend to pursue 50–200 MW 

PV plants as financial investors support the highly reliable technology where PV manufacturers 

provide 25-year module warranties. 
70 

Section 2 Solar Technology Overview provides more details on CSP and PV technology. 

7.4 Preliminary Solar Plant Economics

Like most renewable technologies, there are market driving policies. The main driver has been 

state RPSs, where utility companies are mandated to increase power generation from renewable 

energy resources. State and utility financial incentives, and state and federal tax incentives are 

also allowing the utility-scale solar power cost of electrical generation to approach that of 

conventional fossil fuel-generation plants. 

7.4.1 Federal and States Incentives

Federal incentives for corporate sector developed utility-scale solar projects include:

• Federal Investment Tax Credit: 30% of cost basis, expires 2016 

• 5-year Accelerated Depreciation: no expiration

Arizona incentives for corporate sector-developed projects include: 

• Renewable Energy Production Tax Credit, where: 

o Minimum size is 5 MW

o Maximum incentive of $2 million per year 

o Program budget of $20 million per year on first come, first serve basis (timing is 

critical)

• Energy Equipment Property Tax Exemption: 100% of asset value

• Solar Equipment Sales Tax Exemption: 100% of sales tax on equipment 

The financial and tax incentives for solar equipment for all states with Reclamation lands or 

facilities are provided at http://www.dsireusa.org/incentives/index.cfm?state=us&re=1&EE=1. 

7.5 Modeling Preliminary Economic Feasibility

The NREL-developed System Advisor Model was used to identify the LCOE in ¢/kWh for 

assumed private sector owned and operated solar plants and delivery of electrical production 

through a 20–30 year PPA. 

The following assumptions were established before running the model: 

• All the tax and financial incentives above were applied 

• 30-year financed debt service of 38% with 8% internal rate of return at 6% interest

• Debt service coverage ratio ≥ 1.3

• After-tax internal rate of return = 10%

• Assumed tax equity financial partner with tax appetite to leverage tax incentives

• Land lease = $0 

• Sell price escalation rate = 2.5% (conservative) 
71 

• $3/W for large-scale PV systems (which is realistic based on recent large-scale project 

offers)

• PV system production degradation at 0.5% per year (NREL studies confirmed) 

• $6.20/W for CSP systems (current market rates), which does not vary much by system 

size. 

Models were run for: 

1. 20 MW single-axis PV

2. 50 MW single-axis PV

3. 100 MW single-axis PV

4. 50 MW CSP trough–no storage 

5. 60 MW CSP trough–no storage 

The key results are summarized in Table 7-3. 

Table 7-3. Preliminary Economic Feasibility Model Results

Annual MWh

Capital Cost

($M)

Land Area 

(Acres)

Capacity 

Factor

LCOE

($/kWh)

47,524 60 73 27.1 .104

118,812 141 183 27.1 .101

237,624 286 365 27.1 .101

107,476 275 343 27.6 .172

128,599 329 409 27.5 .175

Initial economic analyses indicate a single-axis tracking PV system may be the most costeffective. The greater production of the single-axis tracking PV system, compared to the fixedmount PV system, more than offsets the higher initial cost of the single-axis tracking PV system. 

The owner of the system would need to sell power for at least the value listed under the LCOE in 

Table 7-3 for the project to be economically feasible. 

This analysis used publicly available capital cost data. Informal discussions with developers 

indicate that current capital costs are lower than those used in the analysis. Thus actual LCOEs 

are likely to be less than shown in the analysis. Recent PPA prices for solar projects appear to be 

in the $0.07-$0.09/kWh range29. In terms of costs of energy, this site appears to be competitive 

for PV and perhaps power tower projects. The current market for solar projects is a bit uncertain. 

Many utilities have met their near- and mid-term renewable portfolio standard requirements for 

solar projects. Utility appetite for further solar projects will depend more upon cost of energy. 

Despite steadily dropping costs for solar energy projects, these projects still have a higher LOCE 

than do natural gas-fired plants.

7.6 Large-Scale Solar Project Development Issues

Development of large-scale renewable energy projects poses a significant challenge to attracting 

high-risk capital from developers and the financial industry. NREL uses a methodology referred 

to as SROPTTC (Site, Resource, Offtaker, Permits, Technology, Team, and Capital), which are 

 

29 Linden, S. “H2 2012 U.S. PPA Market Outlook.” Presented on Oct. 24, 2012. 
72 

incremental actions to be taken to position the proposed project to attract private-sector interest. 

The elements are discussed below together with related federal agency actions.

Site—An assumption for economic modeling was a no-cost lease. This assumption should be 

verified. Alternatives could be an easement or license as no project on federal land could be 

financed without developer access to the site for O&M. There is a cost impact for requiring a 

lease. Typical lease rates are 2% of the project’s direct cost. For example, the 20 MW PV project 

lease rate would be about $1.1M; however, the LCOE would increase to $.105/kWh for the next 

30 years, and the first year cost to the offtaker would be over $50,000. Assuming a 2.5% 

escalation rate, the overall cost of electricity would increase to the offtaker by over $2 million.

Resource—The solar resource is a compelling factor as the Phoenix area has high quality solar 

insolation. However, another resource that needs to be considered is the high use of water for 

CSP thermal electric plants. A wet-cooled 50 MW CSP plant would consume 84 million gallons 

per year, including mirror washing. CSP plants can be dry cooled, reducing water consumption 

to 8 million gallons per year, mostly for mirror washing and boiler make-up water, leading to a 

10% increase in capital cost and $.01/kWh increase in LCOE. By comparison, a 50 MW PV 

system would use 0.017 gallon/MWh or 2,009 gallons/year. Reduced water usage is another 

benefit of PV systems as compared to CSP systems.

Offtaker—As project development proceeds, it is essential to identify who would be the 

purchaser of the electricity produced. Project financing is not feasible without a confident source 

of revenue. This activity involves discussions with utilities or other large consumers that may 

have needs for renewable power (e.g., utility RPS goals) or that need reasonably priced peaking 

power with known projected LCOE.

Permits—This is a broad area of activity but primarily includes:

• National Environmental Policy Act compliance as development is a major action on 

federal land. This issue is always a major deterrent to private sector developers. If 

Reclamation can provide environmental analyses, surveys, assessments to identify 

impacts, and mitigation measures in advance, it would significantly attract industry 

interest.

• Interconnect Agreement. For any new generation plant in excess of 20 MW, the 

developer would need to contribute significant time and financial resources to conduct a 

large generation interconnect process. This involves three stages of studies (12–18 

months and $500,000–$1,000,000) and is usually managed by the entity that owns or 

manages the transmission system for interconnection, often a utility like Arizona Public 

Service. This process is required before the developer could acquire an interconnection 

agreement, which is needed before a PPA could be executed by the proposed offtaker. 

• Other Permits. These vary by state and regulatory bodies requiring permits before 

proceeding with construction and plant operations. 

Technology—This is straightforward as Reclamation has a superior solar resource and is 

focused on solar power projects through PV or CSP.

Team—Development of any large-scale renewable energy project will require a dedicated team 

with mix of skills in contracting, real estate, legal, environmental, engineering and other 

disciplines, and consultants. The team will work collaboratively to address Reclamation’s
73 

requirements along with the needs of the developer so that the federal team provides certainty 

that project development moves forward and mitigates delays.

Capital—There is clear evidence that the financial industry is interested in renewable resource 

investment. Recognizing that reduced uncertainty and commitment by Reclamation to support 

the developer and bringing resources (funding) for the project (e.g., National Environmental 

Policy Act) are key to attracting project capital from the private sector.

7.7 Utility-Scale Analysis—Next Steps

Conduct a Pre-Feasibility Interconnection Study to confirm the transmission lines near the 

project site have the capacity to accept the solar power generated. If transmission access is 

favorable, then: 

1. Brief key Reclamation decision-makers on the potential for large-scale solar project 

development on Reclamation lands 

2. Identify other stakeholders who will be impacted by project development 

3. Prepare a detailed action plan with milestones for project development. 
74 

8 Yuma Utility-Scale Solar Assessment

8.1 Introduction

The Bureau of Reclamation is considering two Reclamation-owned parcels in and around Yuma, 

Arizona, as possible solar generation sites to make land that is not currently used more 

productive. One site is the Yuma Desalting Plant sludge disposal site (A22) near Yuma, Arizona, 

and the other is land located around the Brock Reservoir (Brock), along Interstate 8 in California, 

west of Yuma. The electric load at both sites is relatively small; therefore, the purpose of this 

analysis is for Reclamation to define opportunities using the identified underutilized land for 

solar energy generation and to identify the feasibility for solar developers to obtain use 

authorizations on the land. By identifying potential solar opportunities locally, these projects 

allow Reclamation’s Lower Colorado Region to make progress toward meeting Department of 

the Interior goals for renewable energy while simultaneously creating economic development 

opportunities. 

8.2 Site Descriptions

The two preferred sites for solar power projects on Bureau of Reclamation land near Yuma, 

Arizona, are Brock and A22. Brock is located approximately 22 miles west of Yuma, in Imperial 

County, California. The A22 site is located approximately 13 miles south of Yuma, in Yuma 

County, Arizona. Figure 8-1 and Figure 8-2 show the locations of the two sites. 

Figure 8-1. Proposed solar project locations

Source: Bureau of Reclamation
75 

Figure 8-2. Proposed solar project locations

Source: Google Earth (modified by Blaise Stoltenberg, NREL) 

8.2.1 Brock Reservoir

The proposed site at Brock Reservoir has approximately 2,083 acres available for solar 

generation. The site consists mainly of sandy hummocks and rough terrain, except directly west 

of Brock Reservoir Cell No. 2, which is mostly flat and clear. To the northeast of the site are 

large sand dunes. To the south of the site are Interstate 8, a transmission line corridor, and the 

Mexican border. Some of the land within the parcel has been previously disturbed. For this 

previously disturbed land, environmental analysis is complete and some of the lost habitat has 

already been mitigated. However, certain areas outside the inlet canal’s right-of-way (ROW) 

would require action for National Environmental Policy Act (NEPA) compliance. Additionally, 

because the area is located within the Flat-Tailed Horned Lizard’s (FTHL) East Mesa 

Management Area (MA), conservation measures would apply. These lands have been identified 

to be within the Desert Renewable Energy Conservation Plan (DRECP) boundaries. The west 

end of the site is approximately 2.3 miles from BLM’s Imperial East Solar Energy Zone (SEZ), 

and most of the land area in this SEZ has been applied for by a single solar developer. The parcel 

available for solar development at this site is long and relatively narrow. This shape works fine 

for PV but is not viable for CSP technologies, which need more square or compact layouts to 

reduce thermal losses or to optimize heliostat fields. Figure 8-3 and Figure 8-4 give a close-up of 

the Brock site. 

When looking at the site maps that follow, there is a land classification associated with each 

parcel:
76 

• Class 1—Cleared land, NEPA covered, FTHL mitigation completed, no cultural issues

• Class 2—No prior clearing but NEPA covered, FTHL mitigation completed, no cultural 

issues

• Class 3—No prior clearing, no NEPA coverage, no FTHL mitigation issues, potential 

cultural issues

• Class 4—No prior clearing, no NEPA coverage, potential FTHL mitigation issues and 

cultural issues. 

The definitions for the terms listed in the above classes are as follows:

• Land clearing—The project area was previously cleared of vegetation 

• NEPA coverage—A prior NEPA document previously analyzed the project area 

• FTHL mitigation—Either FTHL mitigation and compensation have been covered for 

project area, and/or FTHL mitigation consisting of fence requirements, biological 

surveys, providing biological monitoring during construction, and paying compensation 

for habitat loss may be required 

• Cultural—The site was previously surveyed and cleared through the State Historic 

Preservation Office (SHPO) or a qualified archeologist.

Figure 8-3. Proposed Brock Reservoir site (west)

Source: Bureau of Reclamation
77 

Figure 8-4. Proposed Brock Reservoir site (east)

Source: Bureau of Reclamation

8.2.2 Site A22

The proposed area at the A22 site has approximately 1,994 acres available for solar generation. 

The site appears to be relatively flat with scattered scrub brush. To the north is irrigated 

cropland, and to the south are County 23rd street and a state prison. An Arizona Public Service 

(APS) distribution line (12 kV) goes through the proposed area, and a substation exists 

approximately 4 miles to the west. A majority of the proposed site is undisturbed and would 

require action for NEPA compliance including biological and cultural consultation with the 

appropriate agencies. The site is located outside the FTHL’s Yuma Desert MA but developing 

the site still may entail conservation measures based on the 2003 FTHL Rangewide Management 

Strategy, an interagency conservation agreement regarding the FTHL. This site could 

accommodate CSP technologies on the southern two sections of land but it probably is not 

practical on the northern half of the site. Figure 8-5 gives a close-up of A22. 
78 

Figure 8-5. Proposed A22 site

Source: Bureau of Reclamation

8.3 Solar Resource

The solar resource in and around Yuma, Arizona, is excellent. The TMY3 weather file for Yuma 

International Airport indicates the global horizontal irradiance (GHI) resource is 1,977 

kWh/m2/yr and the direct normal irradiance (DNI) resource is 2,319 kWh/m2

/yr. This resource is 

good for both PV and CSP and both can be considered. The Yuma TMY3 weather file was used 

by the SAM software to simulate solar generation systems and estimate energy production for 

this analysis. Solar Prospector30 is a tool that displays higher resolution solar only data and 

indicates that the GHI could be 7% higher than the TMY3 and the DNI could be 13% higher. 

The difference is due to how the datasets are derived but the result is that the SAM-calculated 

energy production results are probably conservative estimates. 

Solar resource maps are a quick way to assess the general solar resource of a site. Global solar 

radiation at latitude maps are a good indicator of solar resource for PV systems and are included 

below for both Arizona and California. The concentrating solar map is an indication of solar 

resource for CSP technologies and is included below for Arizona (A22 site). See Figure 8-6, 

Figure 8-7, and Figure 8-8. 

 

30 For more information on the Solar Prospector, see http://maps.nrel.gov/prospector. 
79 

Figure 8-6. California global at latitude tilt solar resource (PV)

Source: NREL
80 

Figure 8-7. Arizona global at latitude tilt solar resource (PV)

Source: NREL
81 

Figure 8-8. Arizona concentrating solar resource (CPV and CSP)

Source: NREL
82 

8.4 Transmission Access

The Brock Reservoir site has a number of transmission and sub-transmission lines adjacent to the 

site. On the site itself is a 34.5 kV sub-transmission line. On the south side of Interstate 8 there 

are a 161 kV, a 92 kV, and a 500 kV transmission lines, and a 34.5 kV sub-transmission line. 

The available capacity on these transmission lines is currently unknown. For this site, the 

economic assumption is that a substation will need to be built to connect to adjacent transmission 

lines at an estimated cost of $4 million. 

The Brock Reservoir site is ideally situated near the North Gila–Imperial Valley 500 kV line, and 

the completion of the Sunrise Project connecting Imperial Valley Substation into the San Diego 

Gas & Electric (SDGE) system will provide opportunity for PV projects in the near term. There 

are also a number of transmission projects in the early development stages, such as the second 

North Gila to Imperial Valley 500 kV line that may provide delivery capability for additional PV 

development in the future. There is much uncertainty about the timing of these transmission 

projects as several seem to be in competition for transmission customers. Some are still working 

through the California Independent System Operator (CAISO) approval process and may drop 

out as a result of the cost allocation for new transmission. 

The sludge disposal site (A22) is approximately 4 miles away from the nearest substation. 

Assuming this is the best place for interconnection, an economic assumption of $4 million for 

transmission lines to the substation was included in the analysis. 

8.5 Analysis Assumptions

The two sites were analyzed with NREL’s SAM to estimate power production and economic

feasibility. Table 8-1 lists the assumptions used in the model. 
83 

Table 8-1. Assumptions Used in Analysis

Property Value Source/Notes

Solar resource data Yuma International Airport TMY3 SAM uses TMY weather files as input 

for solar generation simulations

Project life 30 years

Financing terms 28-year loan at 6% Industry standard is 1-2 years less than 

project life

Debt fraction 47%-48% Adjusted to keep 1st year debt service 

coverage ratio (DSCR) near 1.3

Debt service coverage ratio Near 1.3 (first year) Industry standard

Equity internal rate of return 

(IRR)

15% Common IRR in industry

Project incentives 30% investment tax credit (ITC) and

5-year modified accelerated costrecovery system (MACRS)

DSIRE (www.dsireusa.org)

PPA escalation rate 2% Common escalation rate

PV installed price $2.79/W (fixed) & $3.37/W (1-axis 

tracking)

“Residential, Commercial, and UtilityScale Photovoltaic (PV) System Prices 

in the United States: Current Drivers 

and Cost-Reduction Opportunities,” pg. 

33. 

(www.nrel.gov/docs/fy12osti/53347.pdf)

CSP parabolic trough installed 

price (no storage)

$3.96/W SAM default based on industry contacts 

(no storage, 1.35 solar multiplier, and 

no capital land cost)

CSP power tower installed price 

(6 hours storage)

$5.90/W SAM default based on industry contacts 

and no capital land cost

PV system degradation 0.5% per year www.nrel.gov/docs/fy12osti/53713.pdf

PV O&M cost $30/kW per year for years 1-15 

$20/kW per year for years 16-30

First 15 years builds an escrow account 

for inverter replacement

CSP O&M cost $65/kW and $3/MWh SAM default based on industry contacts

Insurance 0.5% of installed cost per year Industry standard

System capacity 5.75 acres per MW (fixed PV and

CSP), 6.96 acres per MW (1-axis 

track PV)

Based on 4.0 W/ft2 (fixed) and 3.3 W/ft2

(1-axis) from EPA reports

Site lease costs (assumes BLM 

lease rate structure)

BLM Lease Structure:

Two-part fee: Base + Capacity 

(Note: Capacity fee is phased in 

over 5 years)

Brock: Base rent of $188.34/acre

A22: Base rent of $313.88/acre

Brock and A22: 

Capacity Fee: $5,256/MW (PV), 

$6,570/MW (CSP—no storage), 

$7,884/MW (CSP—3 hour or more 

storage)

Based on BLM 2010 rates: 

(http://www.blm.gov/wo/st/en/info/regula

tions/Instruction_Memos_and_Bulletins/

national_instruction/2010/IM_2010-

141.html) 
84 

8.6 Analysis

Table 8-2 and Table 8-3 below highlight the key results for the Brock Reservoir Site and A22 

site, respectively. Results reflect BLM lease rates. The system technologies are listed in order of 

lowest to highest LCOE. 

Table 8-2. Brock Reservoir Analysis Results 

System 

Technology

System 

Size 

(MW)

Net 

Annual 

Energy 

(MWh)

LCOE 

Real

($/kWh)

PPA Price

($/kWh) IRR

Capacity 

Factor

Annual Lease 

Payment ($)a

PV single-axis 

tracking

239 461,670 0.099 0.106 15% 22.1% 1,648,496

PV fixed tilt 290 451,467 0.105 0.112 15% 17.8% 1,916,552 a Lease payment based on BLM CY 2010 formula

Table 8-3. Yuma Desalting Plant Sludge Disposal Site Analysis Results

System 

Technology

System 

Size (MW)

Net 

Annual 

Energy 

(MWh)

LCOE 

Real

($/kWh)

PPA 

Price

($/kWh) IRR

Capacity 

Factor

Annual 

Lease 

Payment 

($)

PV single-axis 

tracking

229 442,353 0.097 0.104 15% 22.1% 1,829,501

PV fixed tilt 277 431,229 0.103 0.110 15% 17.8% 2,081,789

CSP molten salt 

power tower 

(6 hours)

116b 386,859 0.111 0.120 15% 37.9% 1,292,898b

CSP parabolic 

trough

(no storage)

194b 338,699 0.154 0.165 15% 20.0% 1,653,434a

a CSP power plants using only the two southern sections of land (i.e., 1,207 acres), and listed power is 

net power after 8% parasitic losses.

The results of the SAM analysis show that PV with single-axis tracking results in the lowest real 

levelized cost of energy at $0.099 to $0.104 per kWh and also the lowest PPA price at $0.104 to 

$0.106 per kWh. The LCOE for both the Brock Reservoir Site and the Sludge Disposal Site are 

slightly different due to the different land lease payments. The Brock Reservoir Site has the 

potential to produce slightly more power because the location offers more room for solar 

generating equipment. 

The PV technologies have a lower LCOE than the CSP technologies, which is likely due to the 

combination of lower capital costs and lower O&M costs for PV. PV with single-axis tracking 

offers a lower LCOE than PV with a fixed tilt due to a higher capacity factor, offering more 

production despite the slightly higher capital cost. CSP molten salt power tower with storage has 

the highest capacity factor, yet it is not high enough to offset the higher capital cost. The system 

size of CSP molten salt power tower was limited to 116 MW net to optimize the distance 

between the heliostats and the tower for the most favorable production and economics. 
85 

The results show both sites having similar economics and system production. It was assumed 

that land prep was the same for both sites. No property tax was assumed for the renewable 

generation technologies, and a difference in taxation between the sites could also change project 

economics. 

This analysis used publicly available capital cost data. Informal discussions with developers 

indicate that current capital costs are lower than those used in the analysis. Thus actual LCOEs 

are likely to be less than shown in the analysis. Recent PPA prices for solar projects appear to be 

in the $0.07-$0.09/kWh range.31 In terms of costs of energy, this site appears to be competitive 

for PV and perhaps power tower projects. The current market for solar projects is a bit uncertain. 

Many utilities have met their near- and mid-term renewable portfolio standard requirements for 

solar projects. Utility appetite for further solar projects will depend more upon cost of energy. 

Despite steadily dropping costs for solar energy projects, these projects still have a higher LOCE 

than do natural gas-fired plants.

8.7 Next Steps

Should Reclamation decide to move forward with preparing these sites for possible solar energy 

development, NREL recommends the following next steps: 

• Get Brock Reservoir included as a development focus area in the Desert Renewable Energy 

Conservation Plan (see maps below, Figure 8-9 and Figure 8-10) 

• Reclamation to confirm or amend, and finalize a draft Lease of Power Privilege (LOPP) 

D&S document 

• Understand the nature of adjacent land, and the challenges and opportunities it might provide 

(e.g., tribal lands and cultural concerns or BLM lands that might allow for a bigger project). 

 

31 Linden, S. “H2 2012 U.S. PPA Market Outlook.” Presented on Oct. 24, 2012.
86 

Figure 8-9. DRECP starting point map

Source: DRECP/CEC
87 

Figure 8-10. DRECP alternative 5 map

Source: DRECP/CEC
88 

9 Utility-Scale Wind Assessment of North Platte 

Cluster

9.1 Introduction

On May 22, 2012, NREL conducted a site visit to the Reclamation North Platte cluster, located 

roughly 60 miles southwest of Casper, Wyoming, to assess the potential for wind development 

on the Reclamation-owned land in the area. George Neuberger, of the Wyoming Area Office, 

facilitated the site visit. The visit focused on the Morgan Creek area, Seminoe Reservoir/Dam, 

Kortes Reservoir/Dam, and Pathfinder Dam. The methodology used to assess the site is a 

standard high-level “fatal flaw” analysis that looks for key enablers that would encourage wind 

energy development, and also key barriers or “fatal flaws” that would inhibit or preclude wind 

energy development. The site visit looked at the following: wind resource, proximity to 

transmission lines and substations, available land/road access, environmental issues, and 

community receptiveness. 

Figure 9-1 shows the location of the North Platte cluster in south central Wyoming. This area 

was selected for a site visit due to the large potential wind energy capacity of the Reclamation 

owned land, approximately 450 MW, even after applying a series of standard exclusions. 

Figure 9-1. Reclamation North Platte cluster
89 

Figure 9-2. Reclamation North Platte cluster

Source: Bureau of Reclamation 
90 

9.2 Reclamation Land Description

The Reclamation North Platte cluster consists of land adjacent to four reservoirs along the North 

Platte River, which flows from south to north through the area shown in Figure 9-2. From south 

to north the reservoirs are Seminoe, Kortes, Pathfinder, and Alcova. The reservoirs are used for

water supply, recreation, flood control, and electric power generation. Between the reservoirs, 

the North Platte flows through steep, rugged canyons. The area around the reservoirs is a mix of 

rugged terrain and flatter, more rolling terrain as shown in Figure 9-3. 

The Reclamation-owned parcels generally consist of the land directly adjacent to the shoreline 

and along the river. This land is flat in some areas, such as along the northern part of Seminoe 

Reservoir, and rugged in other areas, with steep terrain extending down to the water line. In 

addition to the land adjacent to the water, the Reclamation-owned land includes the Morgan 

Creek area. This is a rugged parcel of terrain located just north of Seminoe Reservoir on the west 

side of the North Platte River. Reclamation-owned land around northern Seminoe Reservoir is 

used as a state park under an agreement with the State of Wyoming. The land adjacent to the 

Reclamation-owned parcels is a mix of public (mostly BLM) land and privately owned land. 

Figure 9-3. Relief map of the North Platte cluster

Source: Bureau of Land Management (using 50 m wind data from NREL)
91 

9.3 Suitability Assessment

9.3.1 Wind Resource

Figure 9-4 shows the wind resource of the area prior to exclusions. The best wind resource 

within the North Platte cluster is along the ridge tops of the Morgan Creek area, which have a 

class IV and class V winds. Immediately adjacent to the reservoirs the wind resource is lower, 

mainly class III. Figure 9-5 gives close-up of the wind resource in the Morgan Creek area and 

northern end of Seminoe Reservoir. Figure 9-6 shows the wind rose for the area. As can be seen, 

the prevailing winds come from the west-southwest. 

Figure 9-4. Reclamation North Platte cluster wind resource

Source: Bureau of Land Management (using 50 m wind data from NREL)
92 

Figure 9-5. Morgan Creek area and northern Seminoe Reservoir wind resource 

(close up of Figure 9-4) 

Source: Bureau of Land Management (using 50 m wind data from NREL)

Figure 9-6. North Platte cluster wind rose 

Source: 3Tier
93 

9.3.2 Available Land/Road Access/Constructability

Overall road access to the general area is adequate. From the north, the area is accessible via 

paved/improved gravel road from Highway 220. From the south, the area is accessible from I-80 

via a paved road. Access to the Morgan Creek area is problematic (Figure 10-7). Seminoe Road 

(an improved gravel road) is marginal, with steep sections and some switchbacks. Morgan Creek 

Road, which accesses some of the ridge tops, is basically a 4-wheel drive road, which is 

completely inadequate for oversized semi-trailers.

The Reclamation-owned land is awkward for wind development purposes. The Reclamationowned parcels consist mainly of the shoreline around the reservoirs plus the Morgan Creek area. 

As discussed, access to Morgan Creek area is problematic. Some of the land around the 

reservoirs is flat and accessible but keeping a multiple-turbine installation within the 

Reclamation boundaries will require long cable runs between turbines, which will lead to 

prohibitive economics. Figure 9-8 shows a demonstrative layout of six 100-m diameter turbines 

on the Reclamation parcel at the north end of Seminoe Reservoir. The red lines show the rows, 

oriented perpendicular to the prevailing winds. The green squares show the turbine locations. 

Turbines within a row are spaced three turbine diameters apart (a typical spacing). The rows are 

six turbine diameters apart (about as close as good practice allows). This is the best possible 

scenario for siting turbine arrays on the Reclamation land in this area. The shape of the 

Reclamation owned parcels does not allow for the economical placement of large turbine arrays.

Figure 9-7. Morgan Creek area road access 

Source: Bureau of Reclamation
94 

Figure 9-8. Hypothetical turbine layout on Reclamation parcel at northern end of Seminoe 

Reservoir 

Source: Google Earth image overlaid with 50 m wind data from NREL (modified by Tony Jimenez) 

9.3.3 Transmission Access

Figure 9-3, Figure 9-4, Figure 9-5, and Figure 9-7 show the power lines and substations that 

serve the area. Interconnection to the grid requires a substation (preferable) or a dedicated switch 

to the power line. The power lines in the area run from the dams. Most of the lines are 115 kV, 

but there is one 230 kV line. Given the voltage ratings of these lines, direct interconnection of 

single turbine would be prohibitively expensive. The six-turbine array shown in Figure 9-8 may 

be large enough to support a dedicated substation or interconnect. 

Figure 9-5 shows the substations located on or near Reclamation-owned land. The figure shows 

three substations located along the North Platte River just downstream (north) of Seminoe River. 

An NREL team was able to visit two of these substations. Of the two substations visited, one is 

located at the base of Seminoe Dam, and the other is at the base of Kortes Dam. The main 

substation serving the area is the Western Area Power Administration (WAPA)-owned “Miracle 

Mile” substation located northeast of the Kortes Dam. This substation is not located on 

Reclamation land. 

Access to the substations is difficult from the areas in which turbines can be built. For example, 

the flat area around the northern part of Seminoe Reservoir is separated from the substation at 

Seminoe Dam by a rugged canyon about two miles in length. 
95 

9.3.4 Environmental

As shown in Figure 9-9, much of the area is listed as sage grouse habitat. Consultation with the 

U.S. Fish & Wildlife Service (USFWS) would be needed for a project to move forward. 

Figure 9-9. Sage grouse habitat in the North Platte cluster

Source: Bureau of Land Management (using 50 m wind data from NREL)

9.3.5 Community Receptiveness

The final consideration is the receptiveness of the local community to a wind project. The 

Reclamation parcel at the north end of Seminoe Reservoir is used as a state park. This was 

discussed with Mr. George Nueberger. While his sense is that most visitors that use the area for 

recreation would probably not object to a wind project, this certainly would need to be 

investigated further. 

9.4 Ownership Structures

This section will briefly describe two potential business models for Reclamation to pursue— 

passive lease holder and Reclamation ownership. When evaluating these models it is important 

to understand a key difference between a hydro facility and a wind farm; unlike water, wind 

cannot be stored for when it is needed. 

The first model is for Reclamation to be a passive leaseholder, collecting royalties for projects 

owned by others that are sited on Reclamation land. This has the advantage of being relatively 

easy. Reclamation would not have to learn all the details of wind farm development and would 

be spared the risks of development. The major disadvantage is that the scale of development is 

dependent on the decisions of others. There are steps Reclamation can take to encourage wind 

projects on Reclamation land but ultimately development is up to others. Should Reclamation 
96 

decide to go this route, we recommend that Reclamation harmonize its processes with BLM to 

attract/allow development from adjacent BLM land. It appears that most Reclamation holdings 

have the same characteristics as the North Platte cluster. The holdings are relatively small and 

awkwardly arranged around bodies of water. This makes it hard to develop large projects solely 

on Reclamation land. However, Reclamation land is often adjacent to much large BLM land 

holdings. In certain locations a developer with a lease on BLM land may find it attractive to 

expand a project onto adjacent Reclamation land. 

Reclamation owns many hydro facilities, and so is used to developing and owning large capital 

intensive projects. Reclamation may decide to develop a wind a wind farm. At this point, such a 

project would benefit from current very low federal government borrowing rates. However, there 

are significant disadvantages. Reclamation would take all the risks of ownership. A governmentowned facility would not benefit from the production tax credit (PTC) or accelerated 

depreciation. Reclamation would have to find buyers of the energy either through PPAs or the 

spot market. Unlike hydro power, the wind cannot be stored. Electricity produced by the wind 

farm has to be sold as it is produced. Finally, the private sector has extensive experience in 

developing and operating wind farms. There doesn’t appear to be a compelling need for large 

scale wind project development by the federal government. 

9.5 Economic Analysis

This section gives an overview of an economic analysis of a hypothetical wind farm located at 

the northern end of Seminoe Reservoir. 

Figure 9-10 shows the wind farm location on the 80 m wind map. The average wind speed [at 80 

m above ground level (AGL)] for the location is shown as lying in the range of 7.0-7.5 m/s. This 

analysis assumes an average wind speed of 7.25 m/s and a Weibull K of 2. 
97 

Figure 9-10. Wind farm location on 80 m wind map 80 m wind data 

Source: EERE/DOE (modified by Tony Jimenez) 

Table 9-1 lists the site and turbine assumptions. Table 9- 2 lists the economic and financial 

assumptions. The air density at the location is estimated to be 0.95 kg/m3

. The site has a lower 

air density due to its elevation. A turbine at this location will produce less energy (given the 

same wind resource) than a turbine at a lower elevation. The turbines used for this analysis are 

GE 1.6-100. This is a 1.6 MW Low Wind Speed Turbines (LWST) turbine with a 100 meter 

rotor. The LWST have extra-long rotors to enable greater energy capture in modest wind 

regimes. Use of this machine in the analysis may be optimistic. Due to the rugged surrounding 

terrain, the winds may be too turbulent to allow use of this machine. Table 9-1 shows the 

expected capacity factor for the GE 1.6-100 and the GE 1.6-82.5. The latter machine has a 

smaller rotor suitable for more turbulent winds than the GE 1.6-100. The wind farm consists of 

six turbines, laid out as shown in Figure 9-8 for a total rated capacity of 9.6 MW. 

Wind Farm 

Location
98 

Table 9-1. Site and Turbine Assumptions

Site Assumptions

Latitude N 42.136

Longitude W 106.896

Elevation 6420 ft (1950 m)

Air Density 0.95 kg/m3

Average Wind Speed at 80 m AGL 7.25 m/s

Weibull k 2.00

Turbine Assumptions

Turbine Loss Factor 15%

Net Capacity Factor (GE 1.6 100 m rotor) 35.7%

Net Capacity Factor (GE 1.6 82.5 m rotor) 31.5%

Wind Farm Rated Capacity 9.6 MW

Start Year 2014

Project Lifetime 20 years

The analysis examined two business models. The “cash-purchase” option assumes the wind farm 

is owned by Reclamation. The “third-party” lease assumes that a third party owns the wind farm, 

leasing the land from Reclamation. 

Table 9-2 lists the economic and financial assumptions. The base-case scenario assumes a total 

installed cost of $2,300/kW. The 2011 Wind Technologies Market Report32 lists an average 

installed cost of $2,300/kW. However, the report anticipates that project costs will drop as recent 

dramatic decreases in turbine hardware costs begin to be reflected in project costs. On the other 

hand, the LWSTs can be expected to have higher per kW costs due to the extra material in the 

blades. Also, a project at this location may have higher than normal interconnection costs. The 

use of $2,300/kW assumes these effects more or less cancel out. This analysis includes a 

sensitivity study over a range of installed costs to determine the effect of changes in the installed 

cost on the cost of energy. 

The analysis assumes an O&M cost of $0.02/kWh (this value comes from the 2011 Wind 

Technologies Market Report). This covers all O&M, including periodic “capital repairs” of large 

components such as blades and gear boxes. After some discussion with Reclamation 

representatives, it was decided to use BLM lease rates for the third-party lease scenario. Per IM 

2009-043, Wind Energy Development Policy, dated Dec. 19, 2009, the analysis used a site 

owner royalty of $4,155/MW/year. The IM has an expiration date of Sept. 30, 2010, but does not 

appear to have been updated. 

 

32 Wiser, R.; Bolinger, M. 2011 Wind Technologies Market Report. Berkeley, CA: Lawrence Berkeley National 

Laboratory, 2012. 
99 

Table 9-2. Economic and Financial Assumptions

Cash Purchase Third Party Lease

Capital Costs

Total Installed Unit Capital Costs ($/kW) $2,300/kW $2,300/kW

Total Installed Capital Cost ($) $22,080,000 $22,080,000

Operating Expenses

Variable O&M $0.02/kWh $0.021/kWh

Variable O&M Escalation Rate 0.9%/year 0.9%/year

Site Owner Royalty ($/MW/yr) 0 $4,155/MW/yr

Financing Assumptions

Debt (% of capital cost) 0 40%

Schedule Type N/A Level Principle

Interest Rate N/A 7%

Term N/A 20 years

Tax Assumptions

Marginal Federal Tax Rate N/A 35%

Marginal State Tax Rate N/A 0%

Incentive Amount (PTC) N/A $0.023/kWh

Incentive Length N/A 10 years

Incentive Escalation Rate N/A 0.9%/year

Economic Assumptions

General Inflation Rate 0.9%/year 0.9%/year

Power Purchaser Discount Rate

(Used for calculating LCOE)

3.9%/year 3.9%/year

Project Owner Discount Rate

(Used for calculating NPV)

3.9%/year 12.9%/year

Minimum IRR 3.9% 10.9%

Energy Payment Escalation Rate 0 0

The inflation rate (0.9%) and discount rates (3.9% nominal) for the cash purchase option were 

determined using the guidelines published by the U.S. Department of Commerce in the annual 

publication, Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis–2011.33

The 12.9% (nominal) project owner discount rate for the third-party lease scenario comes from 

discussions with project developers. 

For the lease option, the analysis assumed a marginal federal tax rate of 35%. Wyoming does not 

have a commercial state income tax so the state tax rate was set at zero percent. However, 

Wyoming does levy a $0.001/kWh tax on commercial wind farms. For simplicity, this was added 

to the overall O&M cost.

The third-party lease scenario benefits from two incentives. The first is the PTC, which is a 

credit given for every kWh sold to an unrelated third party. The credit is available for the first ten 

years of a project and escalates with inflation. The current value (2012) of the credit is 

$0.022/kWh. The estimated value for the 2014 start date used in the analysis is $0.023/kWh. The 

PTC is scheduled to expire at the end of 2013. At the time of this writing, extension is uncertain. 

 

33 Rushing, A.; Lippiatt, B. Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis–2011. U.S. 

Department of Commerce, 2011. Accessed July 2012: http://www1.eere.energy.gov/femp/pdfs/ashb11.pdf. 
100 

If the PTC is not extended, the LCOE of the third-party lease scenario will rise by approximately 

$0.01/kWh for projects that are started after the expiration date. 

The other incentive available to the third-party lease scenario is accelerated depreciation. Under 

the Modified Accelerated Cost Recovery System (MACRS) a wind farm may be depreciated 

over a five-year period, with the bulk of the depreciation available in the first three years. 

Overall assumptions represent the authors’ best effort to develop a middle of the road scenario. 

However, significant uncertainties remain. The study includes a sensitivity analysis over initial 

capital cost and average wind speed to determine the effects of changes in these inputs on the 

levelized cost of energy. 

9.6 Results Discussion

The economic analysis was conducted using the WindFinance34 tool. Analysis results are given 

in Table 9-3 and Table 9-4. The results for the base case are shaded in light yellow. As can be 

seen, the LCOEs for the cash purchase option are lower than the LOCEs for the third-party lease 

option. For the base case, the respective LCOEs are $0.082/kWh for the cash purchase option 

and $0.092/kWh for the lease option. The full range of LCOEs is $0.065/kWh-$0.105/kWh for 

the cash purchase option and $0.070/kWh-$0.140/kWh for the lease option. The LCOE for the 

lease option is more sensitive to changes in the initial capital cost and changes in the average 

wind speed than the LCOE for the cash purchase option. 

There are a couple of likely reasons for why the LCOEs are lower for the cash purchase option 

than for the lease option. The first reason is the current very low IRR that applies to governmentowned projects compared to privately owned projects. The second reason is the modest wind 

resource reduces the value of the PTC. A greater wind resource enables greater energy 

production and thus increases the value of the PTC. Thus, the third-party lease option benefits 

more from a greater wind resource than does the cash purchase option. 

 

34 WindFinance is available at http://analysis.nrel.gov/windfinance/login.asp. 
101 

Table 9-3. Analysis Results–Cash Purchase Option

Cash Purchase

-20% 

Capital 

Cost

-10% 

Capital 

Cost

Base 

Capital 

Cost

+10% 

Capital 

Cost

+20% 

Capital 

Cost

Average Wind Speed = 7.75 m/s

Nominal Levelized Cost of Energy (LCOE) 

(cents/kWh)

6.51 7.05 7.6 8.14 8.68

Real LCOE (start year cents/kWh) 5.98 6.48 6.98 7.48 7.98

Payback Period (years) 14 14 14 14 14

Annual Energy Production (MWh/year) 29,602 29,602 29,602 29,602 29,602

Average Wind Speed = 7.50 m/s

Nominal Levelized Cost of Energy (LCOE) 

(cents/kWh)

6.74 7.32 7.89 8.46 9.04

Real LCOE (start year cents/kWh) 6.2 6.73 7.25 7.78 8.31

Payback Period (years) 14 14 14 14 14

Annual Energy Production (MWh/year) 28,088 28,088 28,088 28,088 28,088

Average Wind Speed = 7.25 m/s

Nominal Levelized Cost of Energy (LCOE) 

(cents/kWh)

7.02 7.63 8.24 8.84 9.45

Real LCOE (start year cents/kWh) 6.45 7.01 7.57 8.13 8.69

Payback Period (years) 14 14 14 14 14

Annual Energy Production (MWh/year) 26,490 26,490 26,490 26,490 26,490

Average Wind Speed = 7.00 m/s

Nominal Levelized Cost of Energy (LCOE) 

(cents/kWh)

7.33 7.98 8.63 9.27 9.92

Real LCOE (start year cents/kWh) 6.74 7.33 7.93 8.52 9.12

Payback Period (years) 14 14 14 14 14

Annual Energy Production (MWh/year) 24,892 24,892 24,892 24,892 24,892

Average Wind Speed = 6.75 m/s

Nominal Levelized Cost of Energy (LCOE) 

(cents/kWh)

7.71 8.4 9.09 9.79 10.48

Real LCOE (start year cents/kWh) 7.08 7.72 8.36 9 9.64

Payback Period (years) 14 14 14 14 14

Annual Energy Production (MWh/year) 23,210 23,210 23,210 23,210 23,210
102 

Table 9-4. Analysis Results–Third-Party Lease

Lease

-20% 

Capital 

Cost

-10% 

Capital 

Cost

Base 

Capital 

Cost

+10% 

Capital 

Cost

+20% 

Capital 

Cost

Average Wind Speed = 7.75 m/s

Nominal Levelized Cost of Energy (LCOE) 

(cents/kWh)

7.04 7.98 8.92 9.86 10.8

Real LCOE (start year cents/kWh) 6.47 7.33 8.2 9.06 9.93

Payback Period (years) 5 5 6 6 6

Annual Energy Production (MWh/year) 29,602 29,602 29,602 29,602 29,602

Average Wind Speed = 7.50 m/s

Nominal Levelized Cost of Energy (LCOE) 

(cents/kWh)

7.45 8.44 9.43 10.42 11.41

Real LCOE (start year cents/kWh) 6.85 7.76 8.67 9.58 10.49

Payback Period (years) 5 6 6 6 6

Annual Energy Production (MWh/year) 28,088 28,088 28,088 28,088 28,088

Average Wind Speed = 7.25 m/s

Nominal Levelized Cost of Energy (LCOE) 

(cents/kWh)

7.94 8.94 10.04 11.09 12.14

Real LCOE (start year cents/kWh) 7.3 8.22 9.23 10.2 11.16

Payback Period (years) 5 6 6 6 6

Annual Energy Production (MWh/year) 26,490 26,490 26,490 26,490 26,490

Average Wind Speed = 7.00 m/s

Nominal Levelized Cost of Energy (LCOE) 

(cents/kWh)

8.48 9.6 10.72 11.84 12.96

Real LCOE (start year cents/kWh) 7.8 8.83 9.86 10.89 11.92

Payback Period (years) 6 6 6 6 6

Annual Energy Production (MWh/year) 24,892 24,892 24,892 24,892 24,892

Average Wind Speed = 6.75 m/s

Nominal Levelized Cost of Energy (LCOE) 

(cents/kWh)

9.15 10.3 11.55 12.75 13.95

Real LCOE (start year cents/kWh) 8.41 9.47 10.61 11.72 12.82

Payback Period (years) 6 6 6 6 6

Annual Energy Production (MWh/year) 23,210 23,210 23,210 23,210 23,210

Wind PPA prices have come down sharply from their 2008-2009 peak. Published data indicates 

that PPA prices for non-California, non-“Wind Belt” projects executed in 2011 were generally in 

the range of $0.04-$0.06 per kWh.35 The estimated LCOEs for this site are higher than current 

PPA prices, indicating that this site is probably uncompetitive for a wind energy project at this 

time but may become more competitive in the future. 

 

35 Wiser, R.; Bolinger, M. 2011 Wind Technologies Market Report. Berkeley, CA: Lawrence Berkeley National 

Laboratory, 2012.
103 

9.7 Overall Conclusions and Recommendations

Wind development is problematic on the Reclamation-owned land in this area. All the potential 

sites have one or more issues. Parts of the Morgan Creek area appear to have a good wind 

resource but these locations are not very accessible. Some of the Reclamation land around 

Seminoe Reservoir is more accessible but it is separated from the substation at Seminoe Dam by 

rugged terrain. This location also suffers from the awkward shape of the Reclamation-owned 

land parcels, which makes compact siting of multiple turbines difficult. A small project may be 

feasible at the north end of Seminoe Reservoir, but overall, none of the sites investigated appear 

compelling. Even if at some future time the economics of a project at the northern end of 

Seminoe Reservoir become more competitive on an absolute basis, it is must be remembered that 

there are nearby non-Reclamation-owned parcels that are more favorable for wind energy 

development. A final possibility is development on BLM land. Due to the extensive BLM land 

holdings in the area, this would open up many new options. 
104 

10Montana Reclamation Lands Wind Screening 

Assessment

10.1Introduction

The Bureau of Reclamation is responsible for a number of reservoirs, canals, and sections of 

water drainages in Montana. As part of Reclamation’s goals to meet agency renewable energy 

targets and/or make its stewardship of the land more productive, the following desktop study was 

completed to screen Reclamation-owned land in Montana for the possibility of installation of 

wind energy generation projects. The study identifies possible project locations. For each 

location, the study provides an estimated maximum project capacity (MW), wind class, 

transmission substation proximity, and other relevant site characteristics.

10.2Methodology

The following is a description of the methodology used to determine the values entered into the 

site matrix and site summary.

NREL developed GIS maps for each of the Reclamation-owned sites in Montana that showed 

potential for wind development. These maps included the boundaries of Reclamation-owned 

land, transmission line location and voltage range, transmission substation location, major roads, 

wind class at 50 meters AGL, areas excluded from wind development, and sage grouse areas. 

These maps were used in conjunction with Google Earth to determine a high-level estimation of 

the appropriateness of Reclamation lands for wind development. The screening criteria used to 

determine if a site should be listed were:

• No obvious environmental show stoppers (a couple of areas have sage grouse habitat that 

may preclude development; these have been identified in the table) 

• Terrain is not too rugged (determined subjectively) 

• Site is not in the middle of a reservoir or active (wet) drainage area

• There appeared to be some road access near the site

• A minimum of three utility-scale wind turbines could be placed at the site.

If a site met these criteria, it was listed even if other considerations were less favorable.

Once a site was identified, an estimation of the number of turbines that could be placed was 

developed using the assumption that the prevailing winds come from the south/southwest. Based 

on a GE 1.6 MW turbine with an 80 m rotor, turbines were placed based on 0.15 miles separation 

between turbines in a row and 0.3 miles separation between rows of turbines. 

For sites meeting the screening criteria, other metrics were determined as follows. The distance 

to a substation was taken from the edge of the site nearest the nearest substation to the substation 

(note: transmission lines to these substations may or may not have available capacity to accept 

wind energy from the site). Wind class at the site was taken from the NREL wind map. Road 

access was determined from Google Earth along with apparent topographical land 

characteristics. Sage grouse areas were based on NREL-produced GIS maps. 
105 

10.3Sites Summary

The sites are summarized in Tables 10-1 through 10-3. Figures 10-1 through 10-6 show maps of 

the sites.

Neither Big Horn County nor Flathead County Reclamation lands meet the screening criteria 

(due to lack of suitable space) and, therefore, determined to have no opportunity for utility-scale 

wind generation. 

Glacier County (Figure 10-1) has a site that is in a valley and meets the screening criteria. It also 

appears to have a substation on site with Highway 89 running through the middle of the site. 

Wind is estimated to be class 3, and there is room for an estimated 92 MW to 96 MW of wind 

turbines.

Chouteau County (Figure 10-2) has what appears to be a large, flat site in farming country. There 

are local roads all around the site. The site is approximately 2.8 miles from the nearest 

substation. An estimated project size on the flat land portion of the site is 339 MW. Wind 

resource is estimated as class 3.

Phillips County (Figure 10-3) has three geographically dispersed sites that meet the screening 

criteria and all have estimated class 3 wind resource. Site PH1 is adjacent to Lake Nelson and 

appears to have a substation and a highway on the site. Estimated generation capacity of the site 

is 67 MW. It has been identified as a sage grouse “75% Lek breeding area,” which may preclude 

development. Site PH2 is about 17 miles south of Lake Nelson in a north-south oriented valley. 

It is approximately 14 miles to the nearest substation and looks to be accessed only by secondary 

roads. Estimated generation capacity of the site is 100 MW. It has been identified as a sage 

grouse “75% Lek breeding area.” Site PH3 is a smaller site about 8 miles west of Malta and 

adjacent to a river system. Local roads access the site and a substation is 2.3 miles away. 

Estimated generation capacity of the site is 19 MW.

Hill County (Figure 10-4) has two sites that have challenges but may merit further analysis. They 

both have estimated class 3 wind resource and neither is identified as a sage grouse area. Site 

HC1 is composed of areas that are close to each other but not contiguous. They appear to be 

relatively flat drainage land in an agricultural area with local roads around the site. The nearest 

substation is 4 miles away and the estimated project size is 77 MW. Site HC2 is near the middle 

of Fresno Reservoir and appears to be a mesa overlooking the reservoir to the southwest. The site 

could accommodate about 28 MW of turbines and is approximately 9.4 miles from a substation. 

A challenge with this site is that it might require about 1.8 miles of road to access the site.

Teton County (Figure 10-5) has seven sites that meet the screening criteria. The sites have a class 

3 to class 4 wind resource. Site T1 is just west of Power, Montana, and included three adjacent 

but not contiguous areas. There appears to be some flat mesa tops around some rugged drainages 

that might be suitable for wind. There are local roads around the site, it is 1.5 miles to the nearest 

substation, and has an estimated capacity of 64 MW. Site T2 is a small area west of Vaughn but 

appears to have a substation on or near the site and highway adjacent the site. The site appears to 

be on the edge of a mesa with about a 6 MW capacity. Site T3 is just south of Fairfield and 

includes two noncontiguous areas that are on the edge of a mesa top. There are local roads near 

the site, and the nearest substation appears to be 0.5 miles away. Estimated capacity for the two 

areas is 9 MW. Site T4 is 3.5 miles west of Fairfield and includes land that appears to be a ridge 

adjacent to rugged drainages. There are local roads around the site, and a substation is on or near 
106 

the site. Site T5 is two noncontiguous areas 9 miles west of Fairfield that sit on an east-west 

ridge. There are local roads around the site, the nearest substation is 2.4 miles away, and the 

estimated wind generation capacity is 72 MW. Site T6 is two areas 4 miles northeast of Willow 

Creek Reservoir. There appears to be flat land with roads to the site and a substation on or 

adjacent to the site. Estimated wind generation capacity is 19 MW. Site T7 is a raised area on the 

northeast shore of Willow Creek Reservoir. There is a local road around the reservoir, and the 

nearest substation is 4 miles away. Estimated wind generation capacity is 16 MW.

Toole and Liberty Counties (Figure 10-6) have three sites that meet the screening criteria. These 

sites have fairly flat areas that overlook the river that drains Lake Elwell. The wind resource is 

primarily class 3 with a couple areas of class 4. Site TL1 is 10 miles southeast of Lake Elwell 

Dam with some secondary drainages that run through the site. There is a highway that runs 

through the site, and it is 2.6 miles to the nearest substation. Estimated site capacity is 27 MW. 

Site TL2 is 13.5 miles from the dam and about 30% of the site has estimated class 4 wind. Local 

roads access the site, and it is 5.3 miles to a substation. Estimated site capacity is 14 MW, which 

is lower than expected based on land area, but the orientation of the site and assumed prevailing 

wind direction reduced the capacity estimate. Site TL3 is 15 miles southeast of the dam and 

includes two nearly contiguous areas. It accessed by local roads and is 6.5 miles to a substation. 

Estimated site capacity is 27 MW.

10.4General Notes, Conclusions, and Next Steps

This study identified Reclamation-owned parcels in Montana that are potential candidates for 

wind energy development. At first pass, the sites appear to have the necessary elements for wind 

energy development—adequate wind resource, transmission access, and road access. The sites 

appear to be free of major fatal flaws, with the possible exception of sage grouse at a couple of 

the locations. On an absolute basis the sites have development potential. However, with only a 

few exceptions, most of the Reclamation-owned parcels in Montana are too small to host large 

wind farms. Chouteau has space for about 340 MW while Glacier and Phillips could each host 

roughly 100 MW each. In most cases, Reclamation-owned parcels would need to be combined 

with non-Reclamation-owned land for there to be enough space for a large wind farm. Many of 

the Reclamation-owned sites in Montana are close to windier sites. The majority of Reclamationowned parcels have a class 3 wind resource. Review of the maps in the section show that most of 

the Reclamation-owned parcels are near areas with a class 4 or greater wind resource. A few 

years ago this would have been a significant disadvantage. This is less true now. High wind 

speed turbines are less efficient and see higher loading. Many developers are starting to prefer 

somewhat less windy sites that allow for deployment of more efficient, lower wind speed 

turbines At first pass, some of the Reclamation-owned parcels appear to have development 

potential, but there does not appear to be a compelling reason to prefer the Reclamation-owned 

parcels over the nearby sites with a similar or greater wind resource.

Should Reclamation decide to continue with this analysis, the recommended next step would be 

to conduct a more in-depth evaluation of the top two or three clusters: Chouteau, Glacier, or 

Phillips. 
107 

Table 10-1. High-Level Wind Energy Potential Assessment for BOR Land in Montana (Part 1)a

Property Est. 

Capacity

(MW) 

Distance to 

Substation 

(miles)

Wind 

Class

Road 

Access

Land 

Characteristics

Sage 

Grouse

Other 

Comments

Big Horn 0 3.2 miles to 

nearest 

nonexcluded 

site (not 

BOR land)

N/A N/A Rugged terrain 

around lake with 

some flat land to 

east of dam

None All areas 

around 

substations are 

excluded

Flathead 0 N/A N/A N/A Fairly rough 

terrain

None Whole area is 

excluded

Glacier 92-96 0 3 Hwy 89 

runs 

through 

area

Appears 

relatively flat 

down in a valley

None

Chouteau 339 2.8 3 Roads all 

around site

Flat plain None

Phillips 

(adjacent to 

Lake 

Nelson)

67 0 3 Road 

through 

middle of 

site

Primarily flat 

with hills in west

75% Lek 

breeding 

area

Fragmented 

land areas

Philips 

(about 17 

mi south 

of Lake 

Nelson)

100 14 3 From 

Earth 

looks like 

some 

secondary 

road 

access 

nearby

Valley 

between hills 

to the east and 

west

75% Lek 

breeding 

area

Philips 

(about 8 

mi west of 

Malta)

19 2.3 3 Road 

appear to 

be around 

the site

Adjacent river 

system; flat 

with hills to the 

south

None Substation is 

on or 

adjacent to 

west end of 

site but river 

bed makes 

development 

up to 

substation 

questionable

Hill County 

(Fresno 

ReservoirSouth end; 

two sites) 

57 + 20 4 3 Roads 

around site

Flat land with 

agriculture 

surrounding site

None Looks like a 

drainage and 

maybe a 

wetland some 

parts of the 

year (two sites) 

Hill County 

(Fresno 

ReservoirMiddle)

28 9.4 3 Would 

require 

about 1.8 

miles of 

new road

Flat mesa top None Nice, welloriented site, 

but road and 

transmission 

access appear 

challenging

a

 Capacity is based on measurements of available land with turbine spacing of 3 diameters and row 

spacing of 6 diameters using a GE 1.6-80.
108 

Table 10-2. High-Level Wind Energy Potential Assessment for BOR Land in Montana (Part 2)

Property Est. 

Capacity

(MW)

Distance 

to 

Substation 

(miles)

Wind 

Class

Road 

Access

Land 

Characteristics

Sage 

Grouse 

Other 

Comments

Teton (just 

west of 

Power)

64 1.5 3 Roads 

around 

site(s)

Drainages None Appears to 

be some 

rugged 

drainage 

terrain with 

some flat 

mesa-type 

land

Teton 

(12.5 

miles

west of 

Vaughn)

6 On or 

adjacent to 

site

3 Hwy 89 

adjacent 

to site

Mesa top with 

valley to south

None

Teton (1.5 

miles

south of 

Fairfield)

9 0.5 3 Roads 

around 

site

Mesa top with 

valley to south

None

Teton (3.5 

miles west 

of 

Fairfield)

56 On or 

adjacent to 

site

3-4 Roads 

around 

site

Flat top ridge 

with sloping 

drainage to 

north and south

None

Teton (9 

miles west 

of 

Fairfield)

72 2.4 3-4 Roads 

around 

site

East-west low 

ridge

None

Teton (4 

miles NE 

of Willow 

Creek 

Reservoir)

19 On or 

adjacent to 

site

3 Road to 

site

Flat land None

Teton (NE 

shore of 

Willow 

Creek 

Reservoir)

16 4 3-4 Road 

around 

reservoir

Low hills None
109 

Table 10-3. High-Level Wind Assessment for BOR Land in Montana (Part 3)a

Property Est. 

Capacity

(MW)

Distance 

to 

Substation 

(miles)

Wind 

Class

Road 

Access

Land 

Characteristics

Sage 

Grouse 

Other 

Comments

TooleLiberty 

(10 miles

SE of

Lake 

Elwell 

Dam)

27 2.6 3-4 Highway 

through 

site

Flat with shallow 

valley to south

None

TooleLiberty 

(13.5 

miles SE 

of Lake 

Elwell 

Dam)

14 5.3 3-4 Country 

agricultural 

roads

Mesa top above 

river

None Site 

oriented on 

NE to SW 

axis. 

Reduced 

number of 

turbines to 

1/0.3 miles

TooleLiberty 

(15 miles

SE of 

Lake 

Elwell 

Dam)

27 6.5 3 Country 

agricultural 

roads

Mesa top above 

river

None Site 

oriented on 

NE to SW 

axis. 

Reduced 

number of 

turbines to 

1/0.3 miles a

 Capacity is based on measurements of available land with turbine spacing of 3 diameters and row 

spacing of 6 diameters using a GE 1.6-80.
110 

Figure 10-1. Glacier County Reclamation-owned land 

Source: Bureau of Land Management (using 50 m wind data from NREL; modified by Blaise Stoltenberg) 

Figure 10-2. Chouteau County Reclamation-owned land 

Source: Bureau of Land Management (using 50 m wind data from NREL; modified by Blaise Stoltenberg) 
111 

Figure 10-3. Phillips County Reclamation-owned land 

Source: Bureau of Land Management (using 50 m wind data from NREL; modified by Blaise Stoltenberg) 

Figure 10-4. Hill County Reclamation-owned land 

Source: Bureau of Land Management (using 50 m wind data from NREL; modified by Blaise Stoltenberg) 
112 

Figure 10-5. Teton County Reclamation-owned land 

Source: Bureau of Land Management (using 50 m wind data from NREL; modified by Blaise Stoltenberg) 

Figure 10-6. Teton and Liberty County Reclamation-Owned Land

Source: Bureau of Land Management (using 50 m wind data from NREL; modified by Blaise Stoltenberg)