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

Feasibility Study of Economics 

and Performance of Solar 

Photovoltaics at the Former 

Chicago, Milwaukee, and St. 

Paul Rail Yard Company Site in 

Perry, Iowa

A Study Prepared in Partnership with the 

Environmental Protection Agency for the 

RE-Powering America’s Land Initiative: 

Siting Renewable Energy on Potentially 

Contaminated Land and Mine Sites

James Salasovich, Jesse Geiger, Victoria

Healey, and Gail Mosey

Produced under direction of U.S. Environmental Protection Agency 

(EPA) by the National Renewable Energy Laboratory (NREL) under 

Interagency Agreement IAG-08-0719 and Task No. WFD3.1001.

Technical Report

NREL/TP-7A40-56793

March 2013 
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

Feasibility Study of Economics 

and Performance of Solar 

Photovoltaics at the Former 

Chicago, Milwaukee, and St. 

Paul Rail Yard Company Site in 

Perry, Iowa 

A Study Prepared in Partnership with the 

Environmental Protection Agency for the 

RE-Powering America’s Land Initiative: 

Siting Renewable Energy on Potentially 

Contaminated Land and Mine Sites

James Salasovich, Jesse Geiger, Victoria

Healey, and Gail Mosey

Prepared under Task No. WFD3.1001

Technical Report

NREL/TP-7A40-56793

March 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: (left to right) PIX 16416, PIX 17423, PIX 16560, PIX 17613, PIX 17436, PIX 17721

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

Acknowledgments

The National Renewable Energy Laboratory (NREL) thanks the U.S. Environmental Protection 

Agency (EPA) for its interest in securing NREL’s technical expertise. In particular, NREL and 

the assessment team for this project are grateful to the Former Chicago, Milwaukee & St. Paul 

Rail Yard Company facility managers, engineers, and operators for their generous assistance 

and cooperation. 

Special thanks go to Shelley Brodie, Shea Jones, Jessica Trice, and Lura Matthews from EPA; 

Katie Brown, AAAS Science & Technology Policy fellow hosted by EPA; and Butch Niebuhr

from the City of Perry for hosting the site visit. The authors would also like to thank Jay Pattee, 

mayor of Perry, for his involvement in the project. 
iv

Executive Summary

The U.S. Environmental Protection Agency (EPA), in accordance with the RE-Powering 

America’s Land initiative, selected the Former Chicago, Milwaukee & St. Paul Rail Yard 

Company site in Perry, Iowa, for a feasibility study of renewable energy production. The 

National Renewable Energy Laboratory (NREL) provided technical assistance for this project. 

The purpose of this report is to assess the site for a photovoltaic (PV) system installation and 

estimate the cost, performance, and site impacts of different PV options. In addition, the report 

recommends financing options that could assist in the implementation of a PV system at the site. 

This study did not assess environmental conditions at the site. 

The main contaminants on the site are polychlorinated biphenyls (PCBs), herbicides, heavy 

metals, and inorganic compounds. The site recently received $400,000 in EPA brownfields 

funding for site assessment and remediation efforts.1 The City of Perry is interested in employing 

the currently underutilized site for solar PV to minimize its impact on the environment. 

The feasibility of installing a PV system depends highly on the land area available for an array, 

solar resource, distance to transmission lines, and distance to major roads. In addition, the 

operating status, ground conditions, and restrictions associated with redevelopment of the 

brownfield site impact the feasibility of a PV system. According to our assessment of these 

factors, the Former Chicago, Milwaukee & St. Paul Rail Yard Company is suitable for 

deployment of a large-scale PV system. 

The Former Chicago, Milwaukee & St. Paul Rail Yard Company site consists of approximately 

138 acres, with two separate areas that are appropriate for installing PV systems. Approximately 

36.6 acres on the east side of the site that are cleared of trees and other shading obstructions are 

currently the most suitable location for a large-scale PV. In addition, 46.2 acres to the west that 

are forested would have to be cleared before a PV system could be installed. Although the entire 

suitable area need not be developed at one time—for example, PV installation could be staged as 

land or funding becomes available—calculations for this analysis reflect the solar potential if the 

total feasible area—82.8 acres—were used. 

The economic feasibility of a potential PV system on the Former Chicago, Milwaukee & St. Paul 

Rail Yard Company site depends greatly on the purchase price of the electricity produced. The 

economics of the potential system were analyzed using Alliant Energy’s current electric rate of 

$0.05/kWh and incentives available to the site owners. Current incentives considered include: 

• Iowa Renewable Energy Production Tax Credit: $0.015/kWh for 10 years for systems 

smaller than 53 MW 

• Iowa Property Tax incentive: 100% exemption of the increased value attributed to a solar 

system for 5 years

• Iowa Sales Tax Incentive: 100% exemption of sales tax for all related solar equipment 

 

1 http://yosemite.epa.gov/opa/admpress.nsf/0/688867BEE7589DEE85257A0F0071A28B. Accessed June 2012. 
v 

 Iowa Alternative Energy Revolving Loan Program: 50% of the financed project cost at a 

0% interested rate for 20 years for a maximum of $1,000,000 

 Alliant Energy Utility Rebate Program: $0.50/kWh for a maximum of $20,000. 

Table ES-1 summarizes the system performance and economics of a system that would use all 

available areas that were surveyed at the Former Chicago, Milwaukee & St. Paul Rail Yard 

Company site. The table shows the annual energy output from the system, the number of average 

American households that such a system could power, and the estimated number of jobs created. 

As indicated in Table ES-1, a 6,400-kW fixed-tilt PV system producing approximately 

8,337,899 kWh annually is not expected to have a payback within the analysis period and a 

negative net present value. This includes the current cost of energy, expected installation cost, 

site solar resource, and existing incentives for the proposed PV system. This savings and 

payback are not deemed practical, and a solar PV system is not a viable use for the site. 

Table ES-1. Former Chicago, Milwaukee & St. Paul Rail Yard Company PV System Summary
vi 

Table of Contents

1 Study and Site Background................................................................................................................. 1

2 Development of a PV System on the Site .......................................................................................... 3

3 PV Systems ........................................................................................................................................... 5

3.1 PV Overview .................................................................................................................................... 5

3.2 Major System Components .............................................................................................................. 5

3.3 Siting Considerations ..................................................................................................................... 11

4 Proposed Installation Location Information .................................................................................... 12

4.1 Utility-Resource Considerations .................................................................................................... 13

4.2 Useable Acreage for PV System Installation ................................................................................. 14

4.3 PV Site Solar Resource .................................................................................................................. 14

4.4 Energy Use on the Site ................................................................................................................... 16

5 Economics and Performance............................................................................................................ 18

5.1 Assumptions and Input Data .......................................................................................................... 18

5.2 Estimated Economic Performance ................................................................................................. 19

5.3 Job Analysis and Impact ................................................................................................................ 22

5.4 Financing Opportunities................................................................................................................. 23

6 Conclusions and Recommendations ............................................................................................... 27

Appendix A. Provided Site Information .................................................................................................. 28

Appendix B. Solar Access Measurements ............................................................................................. 29

Appendix C. Assumptions for the Assessment and Calculations....................................................... 30

Appendix D. Results from the System Advisor Model.......................................................................... 31

Appendix E. Results from the Job and Economic Development Impact Model................................. 43
vii 

List of Figures

Figure 1. Generation of electricity from a PV cell ...........................................................................5

Figure 2. Array for a ground-mounted system.................................................................................6

Figure 3. Mono- and multi-crystalline solar panels .........................................................................7

Figure 4. Thin-film solar panels installed on (left) solar energy cover and (middle, right) fixedtilt mounting system ...................................................................................................................7

Figure 5. String inverter ...................................................................................................................9

Figure 6. Aerial view of the currently feasible area (yellow) for PV and the potentially feasible 

area (blue) for PV at the Former Chicago, Milwaukee & St. Paul Rail Yard Company site ..12

Figure 7. Views of the feasible area for PV at the site ..................................................................13

Figure 8. Electrical transmission lines for the PV system at the site .............................................14

Figure A-1. Contaminated areas at the Former Chicago, Milwaukee & St. Paul Rail Yard 

Company site ...........................................................................................................................28

Figure B-1. Solar access measurements for Former Chicago, Milwaukee & St. Paul Rail Yard 

Company PV site .....................................................................................................................29

Figure D-1. Modeled output for a flat-plate system ......................................................................31

Figure D-2. Modeled output for a single-axis tracking PV system ...............................................32

Figure D-3. LCOE for municipal purchase of a flat-plate system .................................................33

Figure D-4. After-tax cash flow for municipal purchase of a flat-plate system ............................34

Figure D-5. LCOE for a developer-purchased flat-plate system ...................................................35

Figure D-6. After-tax cash flow for a developer-purchased flat-plate system ..............................36

Figure D-7. LCOE for municipal purchase of a single-axis tracking PV system ..........................37

Figure D-8. After-tax cash flow for municipal purchase of a single-axis tracking PV system .....38

Figure D-9. LCOE for a developer-purchased single-axis tracking PV system ............................39

Figure D-10. After-tax cash flow for a developer-purchased single-axis tracking PV system .....40

Figure D-11. Range of LCOE for municipal purchase of a flat-plate system ...............................41
viii

List of Tables

Table ES-1. Former Chicago, Milwaukee & St. Paul Rail Yard Company PV System Summary .v

Table 1. Energy Density by Panel and System (DC-Watts/ft2) .....................................................10

Table 2. Site Identification Information and Specifications ..........................................................15

Table 3. Performance Results for a 20-Degree Fixed-Tilt PV System ..........................................15

Table 4. Performance Results for a Zero-Degree Single-Axis Tracking PV System ....................16

Table 5. Installed System Cost Assumptions ($/Watt) ..................................................................18

Table 6. Economic Results for Four Modeled Cases .....................................................................20

Table 7. PV System Summary .......................................................................................................21

Table 8. LCOE for Single-Axis Tracking PV System After Applied Incentives ..........................22

Table 9. JEDI Analysis Assumptions ............................................................................................23

Table C-1. Cost, System, and Other Assessment Assumptions .....................................................30

Table D-1. Public Funds Allocated to the Project With Analyzed Incentives ...............................42

Table D-2. Amount of Public Funds Used to Lower the LCOE or PPA by $0.01/kWh ...............42

Table E-1. Data Summary for JEDI Model Analysis of a Fixed-Tilt PV System .........................43

Table E-2. Summary of Local Economic Impacts for JEDI Model Analysis of a Fixed-Tilt 

PV System ................................................................................................................................44

Table E-3. Detailed Summary of Costs for JEDI Model Analysis of a Fixed-Tilt PV System .....45

Table E-4. Annual O&M Costs for JEDI Model Analysis of a Fixed-Tilt PV System .................46

Table E-5. Data Summary for JEDI Model Analysis of a Single-Axis Tracking PV System .......47

Table E-6. Summary of Local Economic Impacts for JEDI Model Analysis of a Single-Axis 

Tracking PV System ................................................................................................................48

Table E-7. Detailed Summary of Costs for JEDI Model Analysis of a Single-Axis Tracking PV 

System ......................................................................................................................................49

Table E-8. Annual O&M Costs for JEDI Model Analysis of a Single-Axis Tracking PV 

System ......................................................................................................................................50
1 

1 Study and Site Background

The U.S. Environmental Protection Agency (EPA), in accordance with the RE-Powering 

America’s Land initiative, selected the Former Chicago, Milwaukee & St. Paul Rail Yard 

Company site in Perry, Iowa, for a feasibility study of renewable energy production. The 

National Renewable Energy Laboratory (NREL) provided technical assistance for this 

project. The purpose of this report is to assess the site for a possible photovoltaic (PV) 

system installation and to estimate the cost, performance, and site impacts of different PV 

options. In addition, the report recommends financing options that could assist in 

implementing a PV system at the site. This study did not assess environmental conditions 

at the site. 

The Former Chicago, Milwaukee & St. Paul Rail Yard Company (“the site”) is located in

Perry, Iowa. Perry is located approximately 30 miles northwest of the capital city of Des 

Moines, and it was formerly a major railroad hub. Perry has a population of 7,702 as of 

the 2010 census, and it has been named as one of Iowa’s “Great Places.” Perry has on 

average approximately 200 sunny days per year, and the climate is hot and humid in the 

summer and moderately cold and snowy in the winter. Alliant Energy Corporation, the 

local regulated utility, is the energy holding company that provides electricity to Perry. 

The site consists of approximately 138 acres. From the early 1900s until its closure in 

1986, the site operated as a rail yard and roundhouse (i.e., maintenance facility) for the 

railroads. The City of Perry acquired the site in 2004, but the original owner is the 

responsible party for cleanup of the site. The city has been working diligently to 

remediate the site. The main contaminants on the site are polychlorinated biphenyls 

(PCBs), herbicides, heavy metals, and inorganic compounds. The site recently received 

$400,000 in EPA brownfields funding for site assessment and remediation efforts.2 The 

highest levels of contamination are located where the roundhouse once stood. There are 

concerns with trenching and disturbing the soil at the site because of the contaminants 

present, but there are more clean areas than contaminated areas. Excavating at the site for 

a potential PV system is possible providing there is no potential to run into any 

contaminants. A map of the contaminated areas is given in Appendix A. 

ITC Holdings Corporation owns the 34.5-kV and 161-kV transmission lines that run 

through the site. Alliant Energy Corporation has facilities on ITC-owned transmission 

lines. Interconnection at the 34.5-kV or 161-kV levels is governed by the Midwest 

Independent System Operator (MISO). Performing an interconnection study—a slow and 

costly process—would have to be performed through MISO. There is currently no major 

electricity use at the site. 

Members of the assessment team from NREL, the City of Perry, and the EPA conducted 

a site visit on January 10, 2012, to gather information integral to this feasibility study. 

The team considered information, including solar resource, transmission availability, 

community acceptance, and ground conditions. 

 

2 http://yosemite.epa.gov/opa/admpress.nsf/0/688867BEE7589DEE85257A0F0071A28B. Accessed June 

2012. 
2 

Section 2 outlines some benefits of PV systems on brownfields, and it presents a 

comparable brownfields site on which a PV system was developed. Section 3 presents an 

overview of PV technology, including major system components as well as siting 

considerations. Section 4 summarizes the findings of a site visit and assessment. Section 

5 evaluates the economic performance of a PV system installed on the site. Section 6 

contains the conclusions and recommendations of the assessment team. 
3 

2 Development of a PV System on the Site 

Through the RE-Powering America’s Lands initiative, EPA has identified several 

benefits for siting solar PV facilities on brownfields, noting that they: 

• Can be developed in place of limited greenfields, preserving the land carbon sink 

• May have environmental conditions that are not well suited for commercial or 

residential redevelopment and may be adequately zoned for renewable energy

• Generally are located near existing roads and energy transmission or distribution 

infrastructure

• May provide an economically viable reuse for sites that may have significant 

cleanup costs or low real estate development demand 

• Can provide job opportunities in urban and rural communities 

• Can advance cleaner and more cost effective energy technologies, and reduce the 

environmental impacts of energy systems (e.g., reduce greenhouse gas emissions). 

By taking advantage of these potential benefits, PV can provide a viable, beneficial reuse, 

in many cases, generating significant revenue on otherwise unused sites. 

The City of Perry, which owns the subject site, is interested in potential revenue flows 

from it. The City Solar project in Chicago, Illinois—which represents a site similar to the 

subject site—provides an example of the opportunities realized by other cities that have 

developed PV systems on brownfields. City Solar’s single-axis tracking PV system was 

completed in 2010 on a former industrial site that had been vacant for 30 years. The 

project, which at 10 MW is the largest urban PV system in the United States, is 

comparable in size (41 acres) to the areas available at subject site. The City of Chicago 

owns the City Solar site and leases the land to a solar developer.3

 

For many brownfield sites, the local community has significant interest in redeveloping 

the sites, and community engagement is critical to matching future reuse options with the 

community’s vision for these sites. The subject site could be used for functions other than 

the PV systems proposed in this report. Any potential use should align with the 

community vision for the site and should work to enhance the overall utility of the 

property. Large-scale wind turbines could be installed at the site, if deemed feasible by a 

detailed wind feasibility study, or the site could be used to create a park that is linked to 

the nearby Raccoon River Valley Recreational Trail. 

 

3 http://www.exeloncorp.com/PowerPlants/exeloncitysolar/Pages/Profile.aspx. Accessed July 2012.
4 

There are many compelling reasons to consider moving toward renewable energy sources 

for power generation instead of fossil fuels, including: 

• Renewable energy sources offer a sustainable energy option in the broader energy 

portfolio 

• Renewable energy can have a net positive effect on human health and the 

environment 

• Deployment of renewable energy bolsters national energy independence and 

increases domestic energy security

• Fluctuating electric costs can be mitigated by locking in electricity rates through 

long-term power purchase agreements (PPAs) linked to renewable energy systems 

• Generating energy without harmful emissions or waste products can be 

accomplished through renewable energy sources.
5 

3 PV Systems

3.1 PV Overview

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). Figure 1 shows a generalized model of a solar 

PV electrical current loop. 

Figure 1. Generation of electricity from a PV cell

Source: EPA

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 array. 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 adjoining buildings and facilities or exported to the 

electricity grid. PV system size varies from small residential (2–10 kW), to commercial 

(100–500 kW), to large utility-scale (10+ MW). Central distribution plants are also 

currently being built in the 100+ MW scale. Electricity from utility-scale systems is 

commonly sold back to the electricity grid.

3.2 Major System Components

A typical PV system is made up of several key components, including PV modules, 

inverter, and balance-of-system (BOS) components (e.g., combiner box, transformer, and 

meter). These components (see Figure 2), and other PV system components, are 

discussed below. 

(-)

(+)

-

- -

-

Electron

Current flow

-

Solar cell

- - -

Load
6 

Figure 2. Array for a ground-mounted system

Source: NREL

3.2.1 PV Module

Module technologies are differentiated by the type of PV material used, resulting in a 

range of conversion efficiencies from light energy to electrical energy. The module 

efficiency is a measure of the percentage of solar energy converted into electricity. 

Two common PV technologies that have been widely used for commercial- and utilityscale projects are crystalline silicon and thin film. 

3.2.1.1 Crystalline Silicon

Traditional solar cells are made from silicon. Silicon is quite abundant and nontoxic. It 

builds on a strong industry on both supply (silicon industry) and product side. This 

technology has been demonstrated for a consistent and high efficiency over 30 years in 

the field. The performance degradation, a reduction in power generation due to long-term 

exposure, is under 1% per year. Silicon modules have a lifespan in the 25–30-year range 

but can keep producing energy beyond this range. 

Typical overall efficiency of silicon solar panels is between 12% and 18%. However, 

some manufacturers of mono-crystalline panels claim an overall efficiency nearing 20%. 

This range of efficiencies represents significant variation among the crystalline silicon 

technologies available. The technology is generally divided into mono- and multicrystalline technologies, which indicates the presence of grain-boundaries (i.e., multiple 

crystals) in the cell materials and is controlled by raw material selection and 

manufacturing technique. Crystalline silicon panels are widely used based on 

deployments worldwide. 
7 

Figure 3 shows two examples of crystalline solar panels: mono- and multi-crystalline

installed on tracking mounting systems.

Figure 3. Mono- and multi-crystalline solar panels. Photos by (left) SunPower Corporation, 

NREL 23816 and (right) SunPower, NREL 13823

3.2.1.2 Thin Film

Thin-film PV cells are made from amorphous silicon (a-Si) or non-silicon materials such 

as cadmium telluride (CdTe). Thin-film cells use layers of semiconductor materials only 

a few micrometers thick. Due to the unique nature of thin films, some thin-film cells are 

constructed into flexible modules, enabling such applications as solar energy covers for 

landfills such as a geomembrane system. Other thin-film modules are assembled into 

rigid constructions that can be used in fixed-tilt or, in some cases, tracking system 

configurations. 

The efficiency of thin-film solar cells is generally lower than for crystalline cells. Current 

overall efficiency of a thin-film panel is between 6% and 8% for a-Si and 11% and 12% 

for CdTe. Figure 4 shows thin-film solar panels.

Figure 4. Thin-film solar panels installed on (left) solar energy cover and (middle, right) 

fixed-tilt mounting system. Photos by (left) Republic Services, NREL 23817, (middle) Beck 

Energy, NREL 14726, and (right) U.S. Coast Guard Petaluma Site, NREL 17395

Industry standard warranties of both crystalline and thin-film PV panels typically 

guarantee system performance of 80% of the rated power output for 25 years. After 25 

years, they will continue producing electricity at a lower performance level.
8 

3.2.2 Inverter

Inverters convert DC electricity from the PV array into AC and can connect seamlessly to 

the electricity grid. Inverter efficiencies can be as high as 98.5%. 

Inverters also sense the utility power frequency and synchronize the PV-produced power 

to that frequency. When utility power is not present, the inverter will stop producing AC 

power to prevent “islanding” or putting power into the grid while utility workers are 

trying to fix what they assume is a de-energized distribution system. This safety feature is 

built into all grid-connected inverters in the market. Electricity produced from the system 

may be fed to a step-up transformer to increase the voltage to match the grid. 

There are two primary types of inverters for grid-connected systems: string and microinverters. Each type has strengths and weaknesses and might be recommended for 

different types of installations.

String inverters are most common and typically range in size from 1.5–1,000 kW. These 

inverters tend to be cheaper on a capacity basis, as well as have high efficiency and lower 

operation and maintenance (O&M) costs. String inverters offer various sizes and 

capacities to handle a large range of voltage output. For larger systems, string inverters 

are combined in parallel to produce a single point of interconnection with the grid. 

Warranties typically run between 5 and 10 years with 10 years being the current industry 

standard. On larger units, extended warranties up to 20 years are possible. Given that the 

expected life of the PV panels is 25–30 years, an operator can expect to replace a string

inverter at least one time during the life of the PV system. 

Micro-inverters are dedicated to the conversion of a single PV module’s power output. 

The AC output from each module is connected in parallel to create the array. This 

technology is relatively new to the market and in limited use in larger systems due to the 

potential increase in O&M associated with significantly increasing the number of 

inverters in a given array. Current micro-inverters range in size between 175 W and 

380 W. These inverters can be the most expensive option per watt of capacity. Warranties 

range from 10–20 years. Small projects with irregular modules and shading issues 

typically benefit from micro-inverters. 

With string inverters, small amounts of shading on a solar panel will significantly affect 

the entire array production. Instead, it impacts only that shaded panel if micro-inverters 

are used. Figure 5 shows a string inverter. 
9 

Figure 5. String inverter. Photo by Warren Gretz, NREL 07985

3.2.3 Balance-of-System Components

In addition to the solar modules and inverter, a solar PV system consists of other parts 

called BOS components, which include: 

• Mounting racks and hardware for the panels 

• Wiring for electrical connections. 

3.2.3.1 Mounting Systems

The array has to be secured and oriented optimally to maximize system output. The 

structure holding the modules is referred to as the mounting system. 

3.2.3.1.1 Ground-Mounted Systems

For ground-mounted systems, the mounting system can be either directly anchored into 

the ground (via driven piers or concrete footers) or ballasted on the surface without 

ground penetration. Mounting systems must withstand local wind loads, which range 

from 90–120 mph range for most areas or 130 mph or more for areas with hurricane 

potential. Depending on the region, snow and ice loads must also be a design 

consideration for the mounting system. For brownfield applications, mounting system 

designs will be primarily driven by these considerations coupled with settlement 

concerns. 

Typical ground-mounted systems can be categorized as fixed-tilt or tracking. Fixed-tilt 

mounting structures consist of panels installed at a set angle, typically based on site 

latitude and wind conditions, to increase exposure to solar radiation throughout the year. 

Fixed-tilt systems are used at many brownfield sites. Fixed-tilt systems have lower 

maintenance costs but generate less energy (kWh) per unit power (kW) of capacity than 

tracking systems. 
10 

Tracking systems rotate the PV modules so they are following the sun as it moves across 

the sky. This increases energy output but also increases maintenance and equipment costs 

slightly. Single-axis tracking, in which PV is rotated on a single axis, can increase energy 

output up to 25% or more. With dual-axis tracking, PV is able to directly face the sun all 

day, potentially increasing output up to 35% or more. Depending on underlying soiling 

conditions, single- and dual-axis trackers may not be suitable due to potential settlement 

effects, which can interfere with the alignment requirements of such systems. 

Table 1. Energy Density by Panel and System (DC-Watts/ft2) 

System Type Fixed-Tilt PV

System

Single-Axis Tracking

PV System 

Crystalline Silicon 4.0 3.3

Thin Film 3.3 2.7

Hybrid High

Efficiency

4.8 3.9

The selection of mounting type is dependent on many factors, including installation size, 

electricity rates, government incentives, land constraints, latitude, and local weather. 

Contaminated land applications may raise additional design considerations due to site 

conditions, including differential settlement. 

Selection of the mounting system is also heavily dependent on anchoring or foundation 

selection. The mounting system design will also need to meet applicable local building 

code requirements with respect to snow, wind, and seismic zones. Selection of mounting 

types should also consider frost protection needs especially in cold regions, such as 

New England. 

3.2.3.2 Wiring for Electrical Connections

Electrical connections, including wiring, disconnect switches, fuses, and breakers are 

required to meet electrical code (e.g., NEC Article 690) for both safety and equipment 

protection. 

In most traditional applications, wiring from (1) the arrays to inverters and (2) inverters 

to point of interconnection is generally run as direct burial through trenches. In 

brownfield applications, this wiring may be required to run through above-ground 

conduit due to restrictions with cap penetration or other concerns. Therefore, developers 

should consider noting any such restrictions, if applicable, in requests for proposals in 

order to improve overall bid accuracy. Similarly, it is recommended that PV system 

vendors reflect these costs in the quote when costing out the overall system. 

3.2.3.3 PV System Monitoring 

Monitoring PV systems can be essential for reliable functioning and maximum yield of a 

system. It can be as simple as reading values, such as produced AC power, daily kilowatthours, and cumulative kilowatt-hours, locally on an LCD display on the inverter. For 

more sophisticated monitoring and control purposes, environmental data, such as module 

temperature, ambient temperature, solar radiation, and wind speed, can be collected. 
11 

Remote control and monitoring can be performed by various remote connections. 

Systems can send alerts and status messages to the control center or user. Data can be 

stored in the inverter’s memory or in external data loggers for further system analysis. 

Collection of this basic information is standard for solar systems and not unique to 

landfill applications.

Weather stations are typically installed in large-scale systems. Weather data, such as solar 

radiation and temperature, can be used to predict energy production, enabling comparison 

of the target and actual system output and performance and identification of underperforming arrays. Operators may also use these data to identify required maintenance, 

shade on panels, and accumulating dirt on panels, for example. Monitoring system data 

can also be used for outreach and education. This can be achieved with publicly 

available, online displays; wall-mounted systems; or even smart phone applications. 

3.2.4 Operation and Maintenance

PV panels typically have a 25-year performance warranty. Inverters, which come 

standard with a 5-year or 10-year warranty (extended warranties available), would be 

expected to last 10–15 years. System performance should be verified on a vendorprovided website. Wire and rack connections should be checked annually. This economic 

analysis uses an annual O&M cost computed as $20/kW/year, which is based on the 

historical O&M costs of installed fixed-axis grid-tied PV systems. In addition, the system 

should expect a replacement of system inverters in year 15 at a cost of $0.25/W. 

3.3 Siting Considerations

PV modules are very sensitive to shading. When shaded (either partially or fully), the 

panel is unable to optimally collect the high-energy beam radiation from the sun. As 

explained above, PV modules are made up of many individual cells that all 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 acts as resistance to the whole 

series circuit, impeding current flow and dissipating power rather than producing it. 

The NREL solar assessment team uses a Solmetric SunEye solar path calculator to assess 

shading at particular locations by analyzing the sky view where solar panels will be 

located. By finding the solar access, the NREL team can determine if the area is 

appropriate for solar panels. 

Following the successful collection of solar resource data using the Solmetric SunEye 

tool and determination that the site is adequate for a solar installation, an analysis to 

determine the ideal system size must be conducted. System size depends highly on the 

average energy use of the facilities on the site, PPAs,4 available incentives, and 

utility policy. 

 

4 A PPA is a contract to sell electricity at a negotiated rate for a fixed period. 
12 

4 Proposed Installation Location Information

This section summarizes the findings of the NREL solar assessment site visit on 

January 10, 2012. 

Figure 6, an aerial view of the Former Chicago, Milwaukee & St. Paul Rail Yard 

Company site, shows two portions of the site, one that is currently suitable for a largescale PV system and one that could be made suitable for a PV system.

Figure 6. Aerial view of the currently feasible area (yellow) for PV and the potentially 

feasible area (blue) for PV at the Former Chicago, Milwaukee & St. Paul Rail Yard 

Company site

Illustration done in Google Earth; transmission lines are shown

The area of the site that is currently feasible for installing PV technology (highlighted in 

yellow in Figure 6) consists of 36.6 acres. This area is flat and cleared of trees and other 

shading obstructions. No major infrastructure on this portion of the site would have to be 

removed. The area highlighted in blue on Figure 6, which consists of 46.2 acres, is 

forested and would have to be cleared before a PV system could be installed. For this 

report, only the feasibility of the 36.6-acre area is considered because the 46.2-acre area 

would require significant clearing and leveling before PV could be installed. 

Both the 36.6-acre and the 46.2-acre are close to existing roads. Two transmission lines—

a 34.5-kV line and a 161-kV line—run through the site. To maximize the ground area 

available, it is important that the site developers consider whether the site layout can be 

improved to better incorporate a PV system. If unused structures, fences, and electrical 

poles could be removed from other areas (i.e., those not highlighted in blue or green in 

Figure 6), those areas could be also used for PV panels. 
13 

Figure 7 shows various views of the Former Chicago, Milwaukee & St. Paul Rail Yard 

Company site. 

Figure 7. Views of the feasible area for PV at the site. Photos by Jimmy Salasovich, NREL

PV systems are well suited to the Perry area, where the average global horizontal annual 

solar resource—the total solar radiation for a given location, including direct, diffuse, and 

ground-reflected radiation—is 4.71 kWh/m2

/day. 

4.1 Utility-Resource Considerations

The expected electrical tie-in point for the PV system at the Former Chicago, Milwaukee 

& St. Paul Rail Yard Company site is located within a few miles of the site at a substation 

that is on either the 34.5-kV or the 161-kV line. A detailed interconnection study would 

have to be performed to determine which, if either, transmission line would be suitable. 

The 34.5-kV and 161-kV lines are shown in Figure 8. The tie-in location is limited by the 

available capacity on the transmission lines. Ground disturbances and trenching are not 

allowed at the site because of the contaminants present in the soil; this would increase the 

cost of installing a PV system on the site. When considering a ground-mounted system, 

an electrical tie-in location should be identified to determine how the energy would be 

fed back into the grid. 
14 

Figure 8. Electrical transmission lines for the PV system at the site. Photos by Jimmy 

Salasovich, NREL

4.2 Useable Acreage for PV System Installation 

Typically, a minimum of 2 useable acres is recommended to site PV systems. Useable 

acreage is usually characterized as "flat-to-gently-sloping" southern exposures that are 

free from obstructions and get full sun for at least a 6-hour period each day. For example, 

eligible space for PV includes under-utilized or unoccupied land, vacant lots, and unused 

paved areas (e.g., a parking lot or industrial site space), as well as existing building 

rooftops. The 36.6-acre area is flat and free of all major shading obstructions. 

4.3 PV Site Solar Resource

The Former Chicago, Milwaukee & St. Paul Rail Yard Company site was evaluated using 

onsite data and industry tools to determine the adequacy of the solar resource available. 

The assessment team for this feasibility study collected multiple Solmetric SunEye data

points and found a solar access of 96% and above on the 36.6-acre area. All data gathered 

using this tool are available in Appendix B. 

The predicted array performance was found using PVWatts Version 25 for Perry. Table 2

shows the station identification information, PV system specifications, and energy 

specifications for the site. For this summary array performance information, a 

hypothetical system size of 1 kW was used to show the estimated production for each 

kilowatt so that additional analysis can be performed using the data indicated below. It is 

scaled linearly to match the proposed system size. 

 

5 http://www.nrel.gov/rredc/pvwatts/.
15 

Table 2. Site Identification Information and Specifications

Station Identification

Cell ID 14933

City

State

Des Moines

Iowa

Latitude 41.53° N

Longitude 93.65° W

PV System Specifications

DC Rating 1.00 kW

DC to AC Derate Factor 0.8 

AC Rating 0.8 kW

Array Type Fixed-Tilt 

Array Tilt 20°

Array Azimuth 180°

Energy Specifications

Cost of Electricity $0.05/kWh

Table 3 shows the performance results for a 20-degree fixed-tilt PV system in Perry as 

calculated by PVWatts. 

Table 3. Performance Results for a 20-Degree Fixed-Tilt PV System

Month Solar Radiation

(kWh/m2/day)

AC Energy

(kWh)

Energy Value

($)

1 2.96 78 3.90

2 3.94 92 4.60

3 4.52 113 5.65

4 5.33 124 6.20

5 6.01 137 6.85

6 6.53 143 7.15

7 6.75 148 7.40

8 5.90 131 6.55

9 5.07 111 5.55

10 4.08 97 4.85

11 2.83 66 3.30

12 2.52 64 3.20

Year 4.71 1,303 65.15
16 

Table 4 shows the performance results for a zero-tilt single-axis tracking PV system in 

Perry as calculated by PVWatts. 

Table 4. Performance Results for a Zero-Degree Single-Axis Tracking PV System

Month Solar Radiation

(kWh/m2

/day)

AC Energy

(kWh)

Energy Value

($)

1 2.87 76 3.80

2 4.21 101 5.05

3 5.08 129 6.45

4 6.45 153 7.65

5 7.65 178 8.90

6 8.48 189 9.45

7 8.74 196 9.80

8 7.39 168 8.40

9 5.93 133 6.65

10 4.36 106 5.30

11 2.82 67 3.35

12 2.38 60 3.00

Year 5.54 1,556 77.80

4.4 Energy Use on the Site

The Former Chicago, Milwaukee & St. Paul Rail Yard Company site does not have any 

major electricity use at the site. It is important to understand the application of energy 

generated on the site to enable for a full analysis of whether energy produced would need 

to be sold or whether it could offset future onsite energy use.

4.4.1 Net Metering

Net metering is an electricity policy for consumers who own renewable energy facilities. 

"Net," in this context, is used to mean, "what remains after deductions"—in this case, the 

deduction of any energy outflows from metered energy inflows. Under net metering, a 

system owner receives retail credit for at least a portion of the electricity it generates. 

According to Section 1251 of the Energy Policy Act of 2005, all public electric utilities 

are required to make net metering available to their customers upon request: 

(11) NET METERING.—Each electric utility shall make available upon 

request net metering service to any electric consumer that the electric 

utility serves. For purposes of this paragraph, the term ‘net metering 

service’ means service to an electric consumer under which electric energy 

generated by that electric consumer from an eligible on-site generating 

facility and delivered to the local distribution facilities may be used to 

offset electric energy provided by the electric utility to the electric 

consumer during the applicable billing period. 
17 

Iowa's net-metering law,6 which took effect in 1984, requires utilities to offer net 

metering to all customers with PV, wind, biomass, hydroelectric, municipal solid waste, 

and small hydroelectric systems up to 500 kW.

Renewable energy certificates (RECs),

7 also known as green certificates, green tags, or 

tradable renewable certificates, are tradable commodities in the United States that 

represent proof of electric energy generation from eligible renewable energy resources 

(renewable electricity). The RECs that are associated with the electricity produced and 

are used onsite remain with the customer-generator. If, however, the customer chooses to 

receive financial compensation for the net energy gain remaining after a 12-month 

period, the utility will be granted the RECs associated with only that surplus it purchases. 

Currently, Alliant Energy has more than enough renewables from wind in its renewable 

energy portfolio to meet all state mandates. Therefore, they are not as interested in 

purchasing RECs as they were a few years ago. 

4.4.2 Virtual Net Metering

Under virtual net metering, certain entities, such as a local government, can install 

renewable generation of up to 1 MW at one location within its geographic boundary and 

to generate credits that can be used to offset charges at one or more other locations within 

the same geographic boundary. Some states and utilities allow virtual net metering; Iowa 

does not. 

 

6 For the full text of this bill, see

http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=IA02R&re=0&ee=0. 

7 For a description of RECs, see http://apps3.eere.energy.gov/greenpower/markets/certificates.shtml. 
18 

5 Economics and Performance

NREL evaluated the economic performance of a PV system installed on the site using the 

assumptions and background information discussed in Section 5.1 and several industryspecific inputs determined by other studies. In particular, this study used NREL’s System 

Advisor Model (SAM),8 a performance and economic model designed to facilitate 

decision making for people involved in the renewable energy industry. It makes 

performance predictions for grid-connected solar, solar water heating, wind, and 

geothermal power systems, and it makes economic calculations both for projects that buy 

and sell power at retail rates and for power projects that sell power through PPAs. 

SAM consists of a performance model and financial model. The performance model 

calculates a system's energy output on an hourly basis (sub-hourly simulations are 

available for some technologies). The financial model calculates annual project cash 

flows over a period of years for a range of financing structures for residential, 

commercial, and utility projects. 

SAM makes performance predictions for grid-connected solar, small wind, and 

geothermal power systems, and it makes economic estimates for distributed energy and 

central generation projects. The model calculates the cost of generating electricity based 

on information the user provides about a project's location, installation and operating 

costs, type of financing, applicable tax credits and incentives, and system specifications.

5.1 Assumptions and Input Data

The cost of a PV system depends on the system size and other factors, such as geographic 

location, mounting structure, and type of PV module. Based on significant cost 

reductions seen in 2011, the average cost for utility-scale, ground-mounted systems have 

declined from $4.80/W in the first quarter of 2010 to $2.79/W in the first quarter of 2012. 

With increasing demand and supply, potential of further cost reduction is expected as 

market conditions evolve. 

For this study, the following input data were used. The installed cost of fixed-tilt groundmounted systems was assumed to be $2.79/W, and the installed cost of single-axis

tracking PV was assumed to be $3.35/W. These costs represent best case scenarios for 

purchase price on EPA brownfields. The installed system cost assumptions are 

summarized in Table 5. 

Table 5. Installed System Cost Assumptions ($/Watt)

System Type Fixed-Tilt PV

System

Single-Axis Tracking

PV System

Baseline system 2.79 3.35

 

8 For additional information on SAM, see https://sam.nrel.gov/cost. 
19 

These prices include the PV array and the BOS components for each system, including 

the inverter and electrical equipment, as well as the installation cost. This includes 

estimated taxes and a national-average labor rate but does not include land cost. The 

economics of grid-tied PV depend on incentives, the cost of electricity, the solar resource, 

and panel tilt and orientation. For this analysis, the buyback rate of the electricity was 

assumed to be $0.05/kWh as reported by Alliant Energy.

This analysis assumed that relevant federal incentives are received. It is important to 

consider all applicable incentives or grants to make PV as cost effective as possible. If the 

PV system is owned by a private tax-paying entity, this entity may qualify for federal tax 

credits and accelerated depreciation on the PV system, which can be worth about 15% of 

the initial capital investment. The total potential tax benefits to the tax-paying entity can 

be as high as 45% of the initial system cost. Because state and federal governments do 

not pay taxes, private ownership of the PV system would be required to capture the 

tax incentives. 

For the purposes of this analysis, the project was expected to have a 25-year life, 

although the PV system can be reasonably expected to continue operation past this point. 

Inflation was assumed to be 2.5%; the real discount rate was assumed to be 3% for 

municipalities and 5.85% for private investors; and financing was assumed to be secured 

via a 15-year loan at a 6% interest rate and 55% debt fraction. The panels were assumed 

to have a 0.5% per year degradation in performance. The O&M expenses were estimated 

to be $30/kW/yr for the first 15 years to replace the inverter and $20/kW/yr for the 

remaining 10 years of the study. A system DC-to-AC conversion of 80% was assumed. 

This includes losses in the inverter, wire losses, PV module losses, and losses due to 

temperature effects. PVWatts Version 29 was used to calculate expected energy 

performance for the system. Other assumptions can be found in Appendix C. 

5.2 Estimated Economic Performance

Using the inputs and assumptions summarized in Section 5.1, SAM predicts the internal 

rate of return and the levelized cost of energy (LCOE). Four SAM cases were modeled 

for the site: a direct purchase by the City of Perry and a PPA by an investor with Alliant 

Energy, the local utility company, for both fixed and single-axis tracking modules. No 

cases modeled were economically viable as modeled and would not have a payback by 

the end of the 25-year project lifetime. Table 6 summarizes the economic results for the 

modeled cases. 

 

9 For more information about PVWatts, NREL’s calculator that determines energy production and cost 

savings for grid-connected PV systems, see http://www.nrel.gov/rredc/pvwatts/grid.html. 
20 

Table 6. Economic Results for Four Modeled Cases

Single-Axis Tracking PV System 8,917,949 kWh Annual Production

Municipal Commercial

Breakeven Sale Rate ($/kWh) 0.11 0.091

Payback <25 Years Sale Rate ($/kWh) 0.076 0.056

LCOE ($/kWh) 0.1539 0.0758

Investor-Required PPA Price ($/kWh) 0.1142

Flat-Plate System 8,337,899 kWh Annual Production

Municipal Commercial

Breakeven Purchase Rate ($/kWh) 0.122 0.107

Payback <25 Years Sale Rate ($/kWh) 0.085 0.065

LCOE ($/kWh) 0.1712 0.0891

Investor-Required PPA Price ($/kWh) 0.1277

5.2.1 Flat-Plate Systems

Flat-plate systems are the simplest to set up, and they cost less on a per-watt basis than 

single-axis tracking PV systems. The flat-plate systems allow for a greater portion of area 

to be covered with solar panels but do not have a perpendicular sun angle for much of the 

day, which lowers the amount of energy generating area. For the Perry site, both the cityand investor-purchased cases had a negative net present value and no projected 

payback period. 

5.2.2 Single-Axis Tracking PV Systems 

Using a single-axis tracking PV system lowers the required system size—in comparison 

with a flat-plate system on the same area—but increases the purchase price by 

approximately $0.60/W. Despite being a smaller system, the single-axis tracking PV 

array would produce a 7% increase in electricity generation. The single-axis tracking PV 

system had slightly better economics than the flat-plate system, but they were still very 

unfavorable. 

5.2.3 Variations Between the Investor and Direct Purchase Cases

The City of Perry is a non-taxable entity, which greatly reduces the benefits of immediate 

investment credits to boost the net present value. The investor case modeled has a much 

better net present value due to the offered tax breaks that the city cannot receive. The 

PPA price from the investor is higher than the LCOE of the direct purchase because of 

the expected >15% internal rate of return, which raises the cost to the purchaser. 

All results and a summary of inputs to the SAM are available in Appendix D. A summary 

of the results of the economic analysis and the system considered is available in Table 7. 
21

Table 7. PV System Summary 

5.2.4 Incentives to the Market to Improve Feasibility 

Current market conditions, primarily the maximum PPA rate offered by Alliant Energy, 

prohibit market penetration for solar energy at the site. Because the solar resource and 

incentives at the site are not optimal, the revenue from the low electricity sale price 

would not be able to pay for loan repayments and O&M costs. Improving the revenue 

stream for this and other projects will be crucial to market penetration. Ways to improve 

the revenue stream through policy adjustments already employed by other states include: 

 Implementing virtual net metering, such as the policy in place in New Jersey, 

would take advantage of the large area at the site to eliminate utility costs for the 

municipality. 

 Creating a REC market in Iowa, such as the markets along the East Coast, to sell 

credits from green projects to utilities attempting to meet renewable portfolio 

standards would improve revenue streams. 

These improvements to the revenue stream could make this project, and others like it, 

feasible. Other more quantifiable incentives were analyzed to investigate which policies 

would have the greatest impacts. For this study, the single-axis modeling case was used 

to evaluate the impact on LCOE (for the municipality or investor-owned case) and the 

PPA price in the investor case. The policies evaluated were loan guarantees, capacitybased incentives (CBI), production-based incentives (PBI), and investment tax credits 

(ITC). 
22 

Table 8. LCOE for Single-Axis Tracking PV System After Applied Incentives

Municipal LCOE 

($/kWh)

Commercial 

LCOE ($/kWh)

Investor PPA 

($/kWh)

Loan Guarantees (all pieces) - $0.0104 $0.0644

Extend to 25 years (15 years) - $0.0682 $0.0817

Drop to 3% interest (6%) - $0.0705 $0.0991

100% debt fraction (55%) - $0.0542 * 

CBI

State CBI payment ($0.50/W) $0.1363 $0.0658 $0.0873

State CBI payment ($1/W) $0.1186 $0.0515 $0.0604

PBI (for 10 years)

State PBI payment ($0.02/kWh) $0.1409 $0.0722 $0.0998

State PBI payment ($0.05/kWh) $0.1212 $0.0604 $0.0782

ITC

State ITC 15% No maximum - $0.062 $0.0734

The results show that the largest impact could come from loan guarantees, which lower 

the cost of capital for the project. All incentive types could be used together to maximize 

their individual benefits to generate market penetration. Total government costs were 

calculated for each different incentive; these can be found in Appendix D. Based on these 

totals, the most effective policy of lowering the LCOE and PPA is the unbounded ITC. 

The 15% ITC is currently in place in Iowa with a $15,000 cap; removing that cap would 

create the most cost-effective policy shift. Results for the cost-effectiveness table can be 

found in Appendix D. 

5.3 Job Analysis and Impact

To evaluate the impact on employment and economic impacts of the PV project 

associated with this analysis, we used NREL’s Jobs and Economic Development Impact 

(JEDI) models.

10 The JEDI models are tools that estimate the economic impacts 

associated with the construction and operation of distributed generation power plants. 

The JEDI models are flexible input-output tools that estimate, but do not precisely 

predict, the number of jobs and economic impacts that can be reasonably supported by 

proposed facilities. 

The JEDI models represent the entire economy, including cross-industry or crosscompany impacts. For example, the JEDI models estimate the impact that the installation 

of a distributed generation facility would have on not only the manufacturers of PV 

modules and inverters but also the associated construction materials, metal fabrication 

industry, project management support, transportation, and other industries that are 

required to procure and install a complete system. 

 

10 The JEDI models have been used by the U.S. Department of Energy, the U.S. Department of Agriculture, 

NREL, and the Lawrence Berkeley National Laboratory, as well as several universities. For information on 

JEDI, see http://www.nrel.gov/analysis/jedi/.
23 

For this analysis, the estimated installed project cost ($/kW), targeted year of 

construction, system capacity (kW), O&M costs ($/kW), and location were entered into 

the model to predict the jobs and economic impact. It is important to note that the JEDI 

models do not predict or incorporate any displacement of related economic activity or 

alternative jobs due to the implementation of the proposed project. For this reason, JEDI 

model results are considered gross estimates instead of net estimates. 

For the Former Chicago, Milwaukee & St. Paul Rail Yard Company site, the values in

Table 9 were assumed. 

Table 9. JEDI Analysis Assumptions

Input Assumed Value

Capacity 6,400 kW

Placed In Service Year 2013

Installed System Cost $24,960,000

Location Perry, IA

Using these inputs, the JEDI models estimated the gross direct and indirect jobs, 

associated earnings, and total economic impact supported by the construction and 

continued operation of the proposed PV system 

The estimates of jobs associated with this project are presented as either construction 

period jobs or sustained operations jobs. Each job is expressed as a whole, or fraction, 

full-time equivalent (FTE) position. An FTE is defined 40 hours per week for one person 

for the duration of a year. Construction period jobs are considered short-term positions 

that exist only during the procurement and construction periods. 

As indicated in the results of the JEDI model analysis provided in Appendix E, the total 

proposed system was estimated to support 189.6 direct and indirect jobs per year for the 

duration of the procurement and construction period. Total wages paid to workers during 

the construction period were estimated to be $7,428,300, and total economic output was 

estimated to be $18,727,800. The annual O&M of the new PV system was estimated to 

support 1.9 FTEs per year for the life of the system. The jobs and associated spending 

were projected to account for approximately $98,300 in earnings and $160,300 in 

economic activity each year for the next 25 years. 

5.4 Financing Opportunities

The procurement, development, construction, and management of a successful utilityscale distributed generation facility can be financed a number of different ways. The most 

common ownership and financing structures are described in this section. 

5.4.1 Owner and Operator Financing

The owner/operator financing structure is characterized by a single entity with the 

financial strength to fund all of the solar project costs and, if that entity is a private entity, 

sufficient tax appetite to use all of the project’s tax benefits. Private owners/operators 
24 

typically establish a special purpose entity (SPE) that solely owns the assets of the 

project. An initial equity investment into the SPE is funded by the private entity using 

existing funds and all of the project’s cash flows and tax benefits are used by the entity. 

This equity investment is typically matched with debt financing for the majority of the 

project costs. Project debt is typically issued as a loan based on each owner’s/operator’s 

assets and equity in the project. In addition, private entities can use any of federal tax 

credits offered. 

For public entities that choose to finance, own, and operate a solar project, funding can be 

raised as part of a larger, general obligation bond; as a standalone tax credit bond; 

through a tax-exempt lease structure, bank financing, grant and incentive programs, 

internal cash; or some combination of the above. Certain structures are more common 

than others are, and grant programs for solar programs are on the decline. Regardless, as 

tax-exempt entities, public entities cannot benefit directly from the various tax-creditbased incentives available to private companies. This has given way to the now common 

use of third-party financing structures such as the PPA. 

5.4.2 Third-Party Developers with Power Purchase Agreements

Because many project site hosts do have the financial or technical capabilities to develop 

a capital-intensive project, they often turn to third-party developers (and/or their 

investors). In exchange for access to a site through a lease or easement arrangement, 

third-party developers finance, develop, own, and operate solar projects using their own 

expertise and sources of tax equity financing and debt capital. Once the system is 

installed, the third-party developer sells the electricity to the site host or local utility via a 

PPA. The PPA is typically (1) between the third-party developer and the site host if the 

transaction is a retail “behind-the-meter” transaction or (2) directly with an electric utility 

if it is a wholesale transaction. 

Site hosts benefit by either receiving competitively priced electricity from the project via 

the PPA or from land-lease revenues that they receive for making the site available to the 

solar developer via a lease payment. This lease payment can take on the form of either a 

revenue-sharing agreement or an annual lease payment. In addition, third-party 

developers are able to use federal tax credits. For public entities, this arrangement allows 

them to use the benefits of the tax credits (low PPA price, higher lease payment) while 

not directly receiving them. The term of a PPA typically varies from 20 to 25 years.

5.4.3 Third-Party “Flip” Agreements 

The most common use of this model is a site host working with a third-party developer

who then partners with a tax-motivated investor in an SPE that would own and operate 

the project. Initially, most of the equity provided to the SPE would come from the tax 

investor and most of the benefit (as much as 99%) would flow to the tax investor. When 

the tax investor has fully monetized the tax benefits and achieved an agreed-upon rate of 

return, the allocation of benefits and majority ownership (95%) would “flip” to the site 

host (but not within the first 5 years). After the flip, the site host would have the option to 

buy out all or most of the tax investor’s interest in the project at the fair market value of 

the tax investor’s remaining interest. 
25 

A flip agreement can also be signed between a developer and investors within an SPE, in 

which case, the investor would begin with the majority ownership. Eventually, the 

ownership would flip to the developer once the investor’s return was met.

5.4.4 Hybrid Financial Structures

As the solar market evolves, hybrid financial solutions have been developed in certain 

instances to finance solar projects. A particular structure, nicknamed “The Morris Model” 

after Morris County, New Jersey, combines highly rated public debt, a capital lease, and a 

PPA. Low-interest public debt replaces more costly financing available to the solar 

developer and contributes to a very attractive PPA price for the site hosts. New Markets 

Tax Credits have been combined with PPAs and public debt in other locations, including 

Denver and Salt Lake City. 

5.4.5 Solar Services Agreement and Operating Lease 

The solar services agreement and operating lease business models have been used 

predominately in the municipal and cooperative utility markets for their treatment of tax 

benefits and the rules limiting federal tax benefit transfers from non-profit to for-profit 

companies. Under Internal Revenue Service guidelines, municipalities cannot enter 

capital leases with for-profit entities when the for-profit entities capture tax incentives. 

As a result, several business models, including the solar services agreement, have 

emerged as a work-around to this issue. With a solar services agreement, a private party 

sells “solar services” (i.e., energy and RECs) to a municipality over a specified contract 

period (typically long enough for the private party to accrue the tax credits). The nonprofit utility typically purchases the solar services with either a one-time up-front 

payment equal to the turnkey system cost minus the 30% federal tax credit, or it may 

purchase the services in annual installments. The municipality may buy out the system 

once the third party has accrued the tax credits, but due to Internal Revenue Service

regulations, the buyout of the plant cannot be included as part of the solar services 

agreement (i.e., the agreement cannot be used as a vehicle for a sale and must be a 

separate transaction).

5.4.6 Sale/Leaseback

Various other lease options, which like the solar services agreement, are available to 

municipalities and allow the capture of tax benefits by third-party owners, which results 

in a lower cost to the municipality. These include an operating lease for solar services (as 

opposed to an equipment capital lease) and a complex business model called a 

“sale/leaseback.” Under the sale/leaseback model, the municipality develops the project 

and sells it to a third-party tax equity investor who then leases the project back to the 

municipality under an operating lease. At the end of the lease period, and after the tax 

benefits have been absorbed by the tax equity investor, the municipality may purchase the 

solar project at fair market value.

In this widely accepted model, the public or private entity would install the PV system, 

sell it to a tax investor and then lease it back. As the lessee, they would be responsible for 

operating and maintaining the solar system and they would have the right to sell or use 

the power. In exchange for use of the system, the public or private entity would make 

lease payments to the tax investor (the lessor). The tax investor would have rights to 
26 

federal tax benefits generated by the project and the lease payments. Sometimes, the 

entity is allowed to buy back the project at 100% fair market value after the tax benefits 

are exhausted. 

5.4.7 Community Solar/Solar Gardens

The concept of “community solar” is one in which several participants share the costs and 

benefits of one large solar project. A site owner may be able to make the land available 

for a large solar project, which could then be the basis for a community solar project. 

Ownership structures for these large projects vary, but local utilities typically own or 

sponsor them. Community solar gardens are distributed solar projects wherein utility 

customers have a stake via a prorated share of the project’s energy output. 

This business model is intended to meet demand for solar projects by customers who rent 

or lease homes or businesses, do not have good solar access at their site, or do not want to 

install a solar system on their facilities. Customer prorated shares of solar projects are 

acquired through a long-term transferrable lease of one or more panels, or customers 

subscribe to a share of the project in terms of a specific level of energy output or the 

energy output of a set amount of capacity. Under the customer lease option, the customer 

receives a billing credit for the number of kilowatt-hours their pro-rated share of the solar 

project produces each month; it is also known as virtual net metering. Under the customer 

subscription option, a customer typically pays a set price for a block of solar energy (i.e., 

100-kWh per-month blocks) from the community solar project. Other models include 

monthly energy outputs from a specific investment dollar amount or a specific number 

of panels. 

Community solar garden and customer subscription-based projects can be owned solely 

by the utility; can be owned solely by third-party developers with the utility facilitating 

billing; or may be a joint venture between the utility and a third-party developer leading 

to eventual ownership by the utility after the tax benefits have been absorbed by the thirdparty developer. 

Some states offer solar incentives for community solar projects. For example, 

Washington State offers a production incentive, and Utah offers a state income tax credit. 

Community solar is known as Solar Gardens depending on the location (e.g., Colorado). 
27 

6 Conclusions and Recommendations 

A PV system on the site could generate approximately 8,900 MWh annually and could 

represent a significant distributed generation facility for the area. While reusing land that 

cannot be used for other purposes would minimize the environmental impact of the 

brownfield, using the site for PV is not economically feasible under current conditions. 

As summarized in Section 5, the economic analysis completed using SAM predicts an 

internal rate of return and LCOE of 0% and $0.08–$0.18/kWh, respectively. 

Several policy changes could improve the economics of this and other projects in Iowa. 

The best improvements for commercial investors would be a robust loan guarantee 

program with lowered rates and longer payback periods. These loans could effectively 

lower the cost of production to the PPA price currently offered by Alliant Energy. An 

increase in revenue would also be very important to a solar project’s success. REC 

markets would be very effective in raising the revenue stream for investors to gain greater 

market penetration for renewable energy across the state. The successful shift of any 

policy would require a broad array of policy additions and cooperation with local utilities. 

The best available economic case for the City of Perry would involve setting up multiple 

smaller systems on existing municipal buildings to take advantage of net metering. The 

many different small systems take advantage of tax incentives written to promote small 

electricity generation. Systems ranging in size from 50 kW to 100 kW have payback 

periods from 17 to 18.3 years, respectively. If using a PPA through an investor, over the 

same system size range, the PPA price would range from $0.13/kWh to $0.16/kWh. The

systems would need to be sized according to actual building load and available space. 

Smaller systems were modeled to have lower PPA prices because they take greater 

advantage of incentives; however, systems of smaller sizes will limit investor attraction 

and raise the cost per watt not modeled. 

Investigating state, local, and utility-based policy changes that could make a large-scale 

PV system financially viable is recommended for the City of Perry at this time.
28 

Appendix A. Provided Site Information

Figure A-1 shows contaminated areas at the site. 

Figure A-1. Contaminated areas at the Former Chicago, Milwaukee & St. Paul Rail Yard 

Company site

Source: City of Perry
29 

Appendix B. Solar Access Measurements 

Figure B-1 shows solar access measurements for the Former Chicago, Milwaukee & St. 

Paul Rail Yard Company PV site 

Figure B-1. Solar access measurements for Former Chicago, Milwaukee & St. Paul Rail 

Yard Company PV site
30 

Appendix C. Assumptions for the Assessment 

and Calculations

Table C-1 provides analysis-wide assumptions and important numbers. 

Table C-1. Cost, System, and Other Assessment Assumptions

Cost Assumptions

Variable Quantity of Variable Unit of Variable

Cost of Site Electricity 0.05 $/kWh

Annual O&M (fixed) 30 $/kW/year for first 15 years

System Assumptions

System Type Annual Energy 

(kWh/kW)

Installed Cost

($/W)

Energy Density 

(W/sq. ft.)

Ground Fixed 1,303 $2.79 4.0

Ground Single-Axis 1,556 $3.35 3.3

Other Assumption

Ground utilization 90% of available area
31 

Appendix D. Results from the System Advisor 

Model

Figures D-1 through D-11 show the graphs from the SAM models. Table D-1 and D-2 

show estimates on the impact of policy on both the economics of PV systems and budgets 

of policy implementers. 

Figure D-1. Modeled output for a flat-plate system
32 

Figure D-2. Modeled output for a single-axis tracking PV system
33 

Figure D-3. LCOE for municipal purchase of a flat-plate system
34 

Figure D-4. After-tax cash flow for municipal purchase of a flat-plate system 
35 

Figure D-5. LCOE for a developer-purchased flat-plate system 
36 

Figure D-6. After-tax cash flow for a developer-purchased flat-plate system
37 

Figure D-7. LCOE for municipal purchase of a single-axis tracking PV system
38 

Figure D-8. After-tax cash flow for municipal purchase of a single-axis tracking PV system
39 

Figure D-9. LCOE for a developer-purchased single-axis tracking PV system
40 

Figure D-10. After-tax cash flow for a developer-purchased single-axis tracking PV system
41 

Figure D-11. Range of LCOE for municipal purchase of a flat-plate system

The range is similar for all four cases modeled (see Table 6). 
42 

Table D-1. Public Funds Allocated to the Project With Analyzed Incentives

Municipal Public 

Funds Cost

Commercial Public 

Funds Cost

Investor PPA 

Public Funds Cost

CBI

State CBI Payment ($0.50/W) $2,640,000 $2,640,000 $2,640,000 

State CBI Payment ($1.00/W) $5,280,000 $5,280,000 $5,280,000 

PBI (10 years)

State PBI Payment ($0.02/kWh) $1,743,988 $1,743,988 $1,743,988 

State PBI Payment ($0.05/kWh) $4,359,974 $4,359,974 $4,359,974 

ITC

State ITC (15%, No Max.) $2,653,200 $2,653,200 $2,653,200 

Table D-2. Amount of Public Funds Used to Lower the LCOE or PPA by $0.01/kWh

Municipal 

Effectiveness 

(Incentive 

Dollars)

Commercial LCOE 

Effectiveness 

PPA 

Effectiveness

CBI

State CBI Payment ($0.50/W) $1,500,000 $1,859,154.93 $981,412.64 

State CBI Payment ($1.00/W) $1,495,751 $1,852,631.58 $981,412.64 

PBI (10 years)

State PBI Payment ($0.02/kWh) $1,341,529 $2,235,882 $1,211,103 

State PBI Payment ($0.05/kWh $1,333,325 $2,224,477 $1,211,104 

ITC

State ITC (15%, No Max.) - $1,474,000 $650,294 
43 

Appendix E. Results from the Job and Economic 

Development Impact Model

Tables E-1 through E-8 provide results from the JEDI model 

Table E-1. Data Summary for JEDI Model Analysis of a Fixed-Tilt PV System

Project Location IOWA

Year of Construction or Installation 2013

Average System Size - DC Nameplate Capacity (KW) 6,400.0

Number of Systems Installed 1

Project Size - DC Nameplate Capacity (KW) 6,400.0

System Application Utility

Solar Cell/Module Material Crystalline Silicon

System Tracking Fixed Mount

Total System Base Cost ($/KWDC) $3,900

Annual Direct Operations and Maintenance Cost ($/kW) $25.00

Money Value - Current or Constant (Dollar Year) 2012

Project Construction or Installation Cost $24,960,000

 Local Spending $11,528,641

Total Annual Operational Expenses $3,055,360

 Direct Operating and Maintenance Costs $160,000

 Local Spending $147,200

 Other Annual Costs $2,895,360

 Local Spending $0

 Debt Payments $0

 Property Taxes $0
44 

Table E-2. Summary of Local Economic Impacts for JEDI Model Analysis of a Fixed-Tilt 

PV System

Jobs Earnings Output

During construction and installation period $000 (2012) $000 (2012)

 Project Development and Onsite Labor Impacts

 Construction and Installation Labor 35.1 $2,274.3

 Construction and Installation Related Services 46.3 $1,638.4

 Subtotal 81.5 $3,912.7 $6,933.0

 Module and Supply Chain Impacts

 Manufacturing Impacts 0.0 $0.0 $0.0

 Trade (Wholesale and Retail) 8.8 $420.8 $1,255.1

 Finance, Insurance and Real Estate 0.0 $0.0 $0.0

 Professional Services 10.4 $370.4 $1,254.0

 Other Services 17.0 $1,298.2 $4,497.7

 Other Sectors 32.8 $194.9 $663.1

 Subtotal 69.0 $2,284.2 $7,669.9

 Induced Impacts 36.8 $1,137.3 $3,887.9

 Total Impacts 187.2 $7,334.2 $18,490.7

Annual Annual

Annual Earnings Output

During operating years Jobs $000 (2012) $000 (2012)

 Onsite Labor Impacts

 PV Project Labor Only 1.5 $89.2 $89.2

 Local Revenue and Supply Chain Impacts 0.5 $23.8 $76.6

 Induced Impacts 0.3 $10.4 $35.4

 Total Impacts 2.3 $123.3 $201.1

Notes: Earnings and Output values are thousands of dollars in year 2012 dollars. Construction and

operating period jobs are full-time equivalent for one year (1 FTE = 2,080 hours). Economic impacts "During 

operating years" represent impacts that occur from system/plant operations/expenditures. Totals may not 

add up due to independent rounding.
45 

Table E-3. Detailed Summary of Costs for JEDI Model Analysis of a Fixed-Tilt PV System

IOWA Purchased Manufactured

Installation Costs Cost Locally (%) Locally (Y or N)

Materials & Equipment

 Mounting (rails, clamps, fittings, etc.) $910,236 100% N

 Modules $9,996,622 100% N

 Electrical (wire, connectors, breakers, etc.) $1,037,824 100% N

 Inverter $1,486,677 100% N

 Subtotal $13,431,359

Labor

 Installation $2,274,310 100%

 Subtotal $2,274,310

Subtotal $15,705,669

Other Costs

 Permitting $105,093 100%

 Other Costs $2,322,551 100%

 Business Overhead $6,826,688 100%

 Subtotal $9,254,331

Subtotal $24,960,000

Sales Tax (Materials & Equipment Purchases) $0 100%

Total $24,960,000
46 

Table E-4. Annual O&M Costs for JEDI Model Analysis of a Fixed-Tilt PV System

Cost Local Share

Manufactured 

Locally (Y or N)

Labor

 Technicians $96,000 100%

 Subtotal $96,000

Materials and Services

 Materials & Equipment $64,000 100% N

 Services $0 100%

 Subtotal $64,000

Sales Tax (Materials & Equipment Purchases) $0 100%

Average Annual Payment (Interest and Principal) $2,895,360 0%

Property Taxes $0 100%

Total $3,055,360

Other Parameters

Financial Parameters

Debt Financing

 Percentage financed 80% 0%

 Years financed (term) 10

 Interest rate 10%

Tax Parameters

 Local Property Tax (percent of taxable value) 0%

 Assessed Value (percent of construction cost) 0%

 Taxable Value (percent of assessed value) 0%

 Taxable Value $0

 Property Tax Exemption (percent of local taxes) 100%

 Local Property Taxes $0 100%

 Local Sales Tax Rate 6.00% 100%

 Sales Tax Exemption (percent of local taxes) 100%

Payroll Parameters Wage per hour Employer Payroll Overhead

 Construction and Installation Labor

 Construction Workers / Installers $21.39 45.6%

 O&M Labor

 Technicians $21.39 45.6%
47 

Table E-5. Data Summary for JEDI Model Analysis of a Single-Axis Tracking PV System

Project Location IOWA

Year of Construction or Installation 2013

Average System Size - DC Nameplate Capacity (KW) 5,280.0

Number of Systems Installed 1

Project Size - DC Nameplate Capacity (KW) 5,280.0

System Application Utility

Solar Cell/Module Material Crystalline Silicon

System Tracking Single Axis

Total System Base Cost ($/KWDC) $4,900

Annual Direct Operations and Maintenance Cost ($/kW) $25.00

Money Value - Current or Constant (Dollar Year) 2012

Project Construction or Installation Cost $25,872,000

 Local Spending $13,978,587

Total Annual Operational Expenses $3,133,152

 Direct Operating and Maintenance Costs $132,000

 Local Spending $121,440

 Other Annual Costs $3,001,152

 Local Spending $0

 Debt Payments $0

 Property Taxes $0
48 

Table E-6. Summary of Local Economic Impacts for JEDI Model Analysis of a Single-Axis 

Tracking PV System

Jobs Earnings Output

During construction and installation period $000 (2012) $000 (2012)

 Project Development and Onsite Labor Impacts

 Construction and Installation Labor 31.0 $2,006.5

 Construction and Installation Related Services 60.0 $2,120.1

 Subtotal 90.9 $4,126.6 $8,034.9

 Module and Supply Chain Impacts

 Manufacturing Impacts 0.0 $0.0 $0.0

 Trade (Wholesale and Retail) 11.3 $544.1 $1,623.1

 Finance, Insurance and Real Estate 0.0 $0.0 $0.0

 Professional Services 13.5 $479.4 $1,622.8

 Other Services 22.0 $1,678.7 $5,815.9

 Other Sectors 40.7 $193.3 $651.9

 Subtotal 87.5 $2,895.5 $9,713.7

 Induced Impacts 44.4 $1,372.0 $4,690.1

 Total Impacts 222.8 $8,394.1 $22,438.8

Annual Annual

Annual Earnings Output

During operating years Jobs $000 (2012) $000 (2012)

 Onsite Labor Impacts

 PV Project Labor Only 1.2 $73.6 $73.6

 Local Revenue and Supply Chain Impacts 0.4 $19.6 $63.2

 Induced Impacts 0.3 $8.5 $29.2

 Total Impacts 1.9 $101.7 $165.9

Notes: Earnings and Output values are thousands of dollars in year 2012 dollars. Construction and

operating period jobs are full-time equivalent for one year (1 FTE = 2,080 hours). Economic impacts "During 

operating years" represent impacts that occur from system/plant operations/expenditures. Totals may not 

add up due to independent rounding.
49 

Table E-7. Detailed Summary of Costs for JEDI Model Analysis of a Single-Axis Tracking

PV System

IOWA Purchased Manufactured

Installation Costs Cost Locally (%) Locally (Y or N)

Materials & Equipment

 Mounting (rails, clamps, fittings, etc.) $1,385,875 100% N

 Modules $8,851,968 100% N

 Electrical (wire, connectors, breakers, etc.) $339,124 100% N

 Inverter $1,316,446 100% N

 Subtotal $11,893,413

Labor

 Installation $2,006,508 100%

 Subtotal $2,006,508

Subtotal $13,899,921

Other Costs

 Permitting $141,144 100%

 Other Costs $3,119,290 100%

 Business Overhead $8,711,644 100%

 Subtotal $11,972,079

Subtotal $25,872,000

Sales Tax (Materials & Equipment Purchases) $0 100%

Total $25,872,000
50 

Table E-8. Annual O&M Costs for JEDI Model Analysis of a Single-Axis Tracking

PV System

Cost Local Share

Manufactured 

Locally (Y or N)

Labor

 Technicians $79,200 100%

 Subtotal $79,200

Materials and Services

 Materials & Equipment $52,800 100% N

 Services $0 100%

 Subtotal $52,800

Sales Tax (Materials & Equipment Purchases) $0 100%

Average Annual Payment (Interest and Principal) $3,001,152 0%

Property Taxes $0 100%

Total $3,133,152

Other Parameters

Financial Parameters

Debt Financing

 Percentage financed 80% 0%

 Years financed (term) 10

 Interest rate 10%

Tax Parameters

 Local Property Tax (percent of taxable value) 0%

 Assessed Value (percent of construction cost) 0%

 Taxable Value (percent of assessed value) 0%

 Taxable Value $0

 Property Tax Exemption (percent of local taxes) 100%

 Local Property Taxes $0 100%

 Local Sales Tax Rate 6.00% 100%

 Sales Tax Exemption (percent of local taxes) 100%

Payroll Parameters Wage per hour Employer Payroll Overhead

 Construction and Installation Labor

 Construction Workers / Installers $21.39 45.6%

 O&M Labor

 Technicians $21.39 45.6%