Dennis J. Eichenberg

Glenn Research Center, Cleveland, Ohio

Design of a Glenn Research Center Solar Field 

Grid-Tied Photovoltaic Power System

NASA/TM—2009-216065

December 2009
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Dennis J. Eichenberg

Glenn Research Center, Cleveland, Ohio

Design of a Glenn Research Center Solar Field 

Grid-Tied Photovoltaic Power System

NASA/TM—2009-216065

December 2009

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135
Available from

NASA Center for Aerospace Information

7115 Standard Drive

Hanover, MD 21076–1320

National Technical Information Service

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Level of Review: This material has been technically reviewed by technical management. 
NASA/TM—2009-216065 1 

Design of a Glenn Research Center Solar Field 

Grid-Tied Photovoltaic Power System 

Dennis J. Eichenberg 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

Summary 

The NASA Glenn Research Center (GRC) designed, developed, and installed, a 37.5 kW DC 

photovoltaic (PV) Solar Field in the GRC West Area in the 1970s for the purpose of testing PV panels for 

various space and terrestrial applications. The PV panels are arranged to provide a nominal 120 VDC. 

The GRC Solar Field has been extremely successful in meeting its mission. The PV panels and the 

supporting electrical systems are all near their end of life. GRC has designed a 72 kW DC grid-tied PV 

power system to replace the existing GRC West Area Solar Field. 

The 72 kW DC grid-tied PV power system will provide DC solar power for GRC PV testing 

applications, and provide AC facility power for all times that research power is not required. A grid-tied 

system is connected directly to the utility distribution grid. Facility power can be obtained from the utility 

system as normal. The PV system is synchronized with the utility system to provide power for the facility, 

and excess power is provided to the utility for use by all. 

The project transfers space technology to terrestrial use via nontraditional partners. GRC personnel 

glean valuable experience with PV power systems that are directly applicable to various space power 

systems, and provide valuable space program test data. PV power systems help to reduce harmful 

emissions and reduce the Nation’s dependence on fossil fuels. Power generated by the PV system reduces 

the GRC utility demand, and the surplus power aids the community. 

Present global energy concerns reinforce the need for the development of alternative energy systems. 

Modern PV panels are readily available, reliable, efficient, and economical with a life expectancy of at 

least 25 years. Modern electronics has been the enabling technology behind grid-tied power systems, 

making them safe, reliable, efficient, and economical with a life expectancy of at least 25 years. 

The report concludes that the GRC West Area grid-tied PV power system design is viable for a 

reliable, maintenance free, long life power system that is of significant value to NASA and the 

community. 

Introduction 

The NASA Glenn Research Center has a wealth of experience in photovoltaic power systems. The 

work was done under the Hybrid Power Management (HPM) Program. The GRC Electrical and 

Electromagnetics Branch initiated the HPM Program for the GRC Technology Transfer and Partnership 

Office. HPM is the innovative integration of diverse, state-of-the-art power devices in an optimal 

configuration for space and terrestrial applications. The appropriate application and control of the various 

power devices significantly improves overall system performance and efficiency. Applications include 

power generation, transportation systems, biotechnology systems, and space power systems. 

A PV power system can either be a stand alone, off-grid system, or a grid-tied system. An off-grid PV 

system provides local power only. A grid-tied PV system is connected directly to the utility distribution 

grid. Facility power can be obtained from the utility system as normal. The PV system is synchronized 

with the utility system. The PV system provides power for the facility, and excess power is provided to 

the utility. 

Photovoltaic power systems have tremendous potential. The 89 petawatts of sunlight reaching the 

Earth’s surface is approximately 6,000 times greater than the 15 terawatts of average power consumed by 
NASA/TM—2009-216065 2 

the human population. PV generation has the highest power density of renewable energies with a global 

mean of 170 W/m2

 (Ref. 1). PV is entirely pollution free during use. PV system production end wastes 

and emissions are manageable utilizing existing pollution controls. End-of-use recycling technologies are 

under development to minimize negative environmental effects. PV systems can operate with minimal 

operator intervention or maintenance after initial setup. 

Grid-tied PV power systems provide many benefits. Operating costs of a PV power system are low 

compared to conventional power technologies. PV can displace the highest cost electricity during times of 

peak demand in most climatic regions, and thus reduce grid loading. Net Metering is often used, in which 

independent power producers, such as PV power systems, are connected to the utility grid via the 

customers’ main service panel and meter. When the PV power system is generating more power than 

required at that location, the excess power is provided to the utility grid. The customer pays the net of the 

power purchased when the on-site power demand is greater than the on-site power production and the 

excess power that is returned to the utility grid. 

Grid-tied PV power systems can be used locally thus reducing transmission/distribution losses. 

Transmission/distribution losses in the U.S. were approximately 7.2 percent in 1995 (Ref. 2), thus 

providing a potential for significant energy savings. 

The GRC West Area 72 kW grid-tied PV power system can be used for photovoltaic power testing, as 

it has traditionally, and also be used to provide grid-tied utility power when photovoltaic research power 

is not required. Theoretical power generation has been determined for the GRC West Area 72 kW gridtied PV power system. 

Analysis 

Predicted Power Generation 

The National Renewable Energy Laboratory has developed a calculator to determine the energy 

production of grid-tied PV power systems throughout the world. The calculator is based upon the work of 

David F. Mennicucci (Ref. 3). 

The calculator creates hour-by-hour performance simulations that provide power estimated monthly 

and annual energy production in kilowatts and energy value. Users can select a location and choose to use 

default values or their own system parameters, for size, electricity cost, array type, tilt angle, and azimuth 

angle. The calculator can provide hourly performance data for the selected location. 

The calculator uses typical meteorological year weather for the selected location, and determines the 

incident PV array solar radiation and the PV cell temperature for each hour of the year. The DC energy 

for each hour is calculated from the PV system DC rating and the incident solar radiation, and then 

corrected for the PV cell temperature. The AC energy for each hour is calculated by multiplying the DC 

energy by the overall DC-to-AC derating factor and adjusting for the inverter efficiency as a function of 

the load. Hourly values of AC energy are summed to determine monthly and annual AC energy 

production. 

A PV system is rated upon its nameplate DC power rating. This is determined by adding the PV panel 

power listed on the nameplates of the PV panels in watts (W), and dividing the sum by 1,000 to convert 

the rating to kilowatts (kW). PV panels are rated for standard test conditions of 1,000 W/msolar 

irradiance, and 25 °C PV panel temperature. 

The PV system AC rating is determined by multiplying the nameplate DC power rating by an overall 

DC-to-AC derating factor. The DC-to-AC derating factor account for losses from the DC nameplate 

power rating, and is the mathematical product of the derating factors for the components of the PV 

system. The derating factor components includes PV array nameplate DC rating accuracy, inverter and 

transformer losses, mismatch, diode and connection losses, DC wiring losses, AC wiring losses, PV array 

contamination, system availability, and shading. 

The derating factor for PV array contamination accounts for snow and other foreign matter on the 

surface of the PV array that prevents solar radiation from reaching the solar cells. PV array contamination 
NASA/TM—2009-216065 3 

is location and weather dependent. There are greater contamination losses in high-traffic, high pollution 

areas with infrequent rain. Snow reduces energy produced, and the severity is a function of the amount of 

snow and the duration that it remains on the PV array. Snow remains the longest when sub-freezing 

temperatures prevail, small PV array tilt angles prevent snow from sliding off, the PV array is closely 

integrated onto the roof, and the roof, or another structure in the vicinity, facilitates snow drift onto the 

array. 

The tilt angle for a fixed array is the angle from horizontal of the inclination of the PV array. Thus a 

tilt of 0° is a horizontal array, and a tilt of 90° is a vertical array. An array is normally tilted at the 

location’s latitude. This normally maximizes annual energy production. Increasing the tilt angle favors 

energy production in the winter, and decreasing the tilt angle favors energy production in the summer. 

The azimuth angle for a fixed array is the angle clockwise from true north that the PV array faces. An 

azimuth angle of 180° (south-facing) is normally used for locations in the northern hemisphere, and 0° 

(north-facing) for locations in the southern hemisphere. This normally maximizes energy production. For 

the northern hemisphere, increasing the azimuth angle favors afternoon energy production, and decreasing 

the azimuth angle favors morning energy production. For the southern hemisphere, decreasing the 

azimuth angle favors afternoon energy production, and increasing the azimuth angle favors morning 

energy production. 

The monthly and yearly energy production estimates are modeled using the selected PV system 

parameters and weather data that are typical or representative of long-term averages. Weather patterns 

vary from year to year, so the model is a better indicator of long-term performance than of performance 

for a particular month or year. PV performance is largely proportional to the solar radiation received, 

which may vary from the long-term average by 30 percent monthly and 10 percent yearly. For these 

variations, and the uncertainties associated with the weather data and model, future months and years may 

have actual PV performance that differs from the model. The variations may be as much as 40 percent for 

individual months, and up to 20 percent for individual years. Long-term performance over many years is 

expected to be accurate within 10 percent. 

There are other factors that affect model accuracy. Nearby buildings, objects, or other PV arrays and 

array structures that shade the PV array will cause a reduction in actual energy production from the 

model. Snow or other contamination of the PV array will cause an inconsistency with the model. There is 

a reduction in power generation over time that is not factored into the model. Aging is due to weathering 

of the PV array, and is typically 1 percent per year. 

The predicted AC energy for a grid-tied 72 kW DC PV power system located in Cleveland, Ohio is 

shown in Table 1. The assumptions made for this prediction is that the PV array is crystalline silicon, the 

PV array is fixed at a tilt of 41.4°, the PV array azimuth is 180.0°, and the DC-to-AC derating factor is 

0.770. The predicted AC energy is shown graphically in Figure 1. 

TABLE 1.—PREDICTED ENERGY FOR A GRID-TIED 

72 kW DC PHOTOVOLTAIC POWER SYSTEM 

IN CLEVELAND, OHIO 

Month Solar radiation, 

kWh/m2

/day 

AC energy, 

kWh 

January 2.49 4403 

February 3.34 5284 

March 4.09 7042 

April 4.94 7975 

May 5.48 8763 

June 5.56 8319 

July 5.55 8544 

August 5.47 8467 

September 4.90 7494 

October 3.91 6359 

November 2.18 3398 

December 1.68 2749 

Total annual 4.14 78797 
NASA/TM—2009-216065 4 

Figure 1.—Predicted AC Energy for a Grid-Tied 72 kW DC Photovoltaic Power System in Cleveland, Ohio. 

TABLE 2.—PREDICTED ANNUAL AC ENERGY 

FOR A GRID-TIED 72 kW DC PHOTOVOLTAIC 

POWER SYSTEM 

City Tilt, 

degrees 

Annual AC 

energy, 

kWh 

Cleveland 41.4 78797 

Tampa 28.0 98197 

Los Angeles 33.9 105821 

Phoenix 33.4 116421 

Las Vegas 36.1 119775 

Anchorage 61.2 57173 

Montreal 45.5 79236 

Berlin 52.5 54304 

Matsumoto 36.2 85240 

Moscow 55.8 55214 

Paris 48.7 58723 

The predicted annual AC energy produced from a grid-tied 72 kW DC PV power system for different 

areas throughout the world are shown in Table 2. The assumptions made for this prediction is that the PV 

array is crystalline silicon, the PV array tilt is fixed at the appropriate angle for the specific location, the 

PV array azimuth is 180.0°, and the DC-to-AC derating factor is 0.770. It is interesting to note from the 

world comparison that Cleveland is a viable location for PV energy production, with potentially 

significantly greater annual energy production than Berlin, Moscow or Paris for the same PV system 

properly oriented for the specific location. In addition, the potential annual energy production from the 

same PV system in Cleveland is not significantly less than such a system located in Tampa. 
NASA/TM—2009-216065 5 

Hardware Description 

GRC West Area Photovoltaic Power System 

The NASA Glenn Research Center (GRC) designed, developed, and installed, a 37.5 kW DC 

photovoltaic (PV) Solar Field in the GRC West Area in the 1970s for the purpose of testing PV panels for 

various space and terrestrial applications. The PV panels are arranged to provide a nominal 120 VDC. 

The existing Solar Field is shown in Figures 2 and 3. The system block diagram is shown in Figure 4. 

System component specifications are included in the Appendix. The GRC Solar Field has been extremely 

successful in meeting its mission. The PV panels and the supporting electrical systems are all near their 

end of life. GRC has designed a 72 kW DC grid-tied PV power system to replace the existing GRC West 

Area Solar Field. 

Figure 2.—Front View of the Existing GRC West Area Solar Field. 

Figure 3.—Rear View of the Existing GRC West Area Solar Field. 
NASA/TM—2009-216065 6 

Figure 4.—Existing GRC West Area Solar Field. 

Figure 5.—Proposed GRC West Area 72 kW Grid-Tied Photovoltaic System Block Diagram. 

The 72 kW DC grid-tied PV power system will provide DC solar power for GRC PV testing applications, 

and provide AC facility power for all times that research power is not required. A grid-tied system is 

connected directly to the utility distribution grid. Facility power can be obtained from the utility system as 

normal. The PV system is synchronized with the utility system to provide power for the facility, and 

excess power is provided to the utility for use by all. The 72 kW DC grid-tied PV power system hardware 

includes the photovoltaic panels, a source circuit combiner, and the DC/AC inverter. The design of the 

system is based upon the GRC prototype 2 kW grid-tied photovoltaic power system that has been 

operating flawlessly at GRC since 2006 (Ref. 4), as well as the GRC Visitor’s Center grid-tied 

photovoltaic power system that has been operating equally as well at GRC since 2008 (Ref. 5). The 

72 kW DC grid-tied PV power system block diagram is shown in Figure 5. System component 

specifications are included in the Appendix. 
NASA/TM—2009-216065 7 

The photovoltaic panels selected for the 72 kW DC grid-tied PV power system are semiconductor 

panels that convert energy from sunlight to DC electrical power. The panels are unbreakable and 

maintenance free. The system consists of 360 solar panels, each rated for 200 W DC at 27.1 V. Each 

panel consists of 54 silicon poly-crystalline cells in series. The panel efficiency in providing power from 

the sunlight is rated at 15 percent. Each panel weighs 39 lb, and is 58.5 by 38.6 in. The life expectancy of 

the PV panels is 25 years or greater. The support structure for the panels is a fixed mount to orient the 

panels southerly with a tilt of 41.4° from horizontal to align the panels for the latitude of Cleveland, Ohio. 

Solar trackers are available to increase the available power from the Sun. Under ideal conditions, a tracker 

can provide up to 50 percent additional daily power from a PV array. In temperate latitudes, a tracker can 

provide an annual 25 percent increase in power from a PV array. Numerous technologies are available for 

trackers, including electric drives and fluid drives. Trackers are mechanical devices, and thus have 

potential life and maintenance issues. To avoid life and maintenance concerns, a fixed mount was selected 

for the GRC West Area 72 kW PV power system design. 

The 360 PV panels are configured as 24 sets of 15 panels in series. Each of the 24 circuits is 

connected to a source circuit combiner. The combiner provides 15 A fuse protection for each of the 

circuits. The combiner weighs 45 lb, and is 20 by 20 by 6 in. The output of the combiner is a single DC 

output that feeds the photovoltaic inverter. The selected inverter converts the DC electrical power derived 

from the photovoltaic panels to three phase, 60 Hz, sinusoidal AC power synchronized to the AC utility 

power system. The inverter is rated at 75 kW, 480 VAC three phase with an efficiency of 95.5 percent. 

The inverter weighs 2,750 lb, and is 35.0 by 92.4 by 62.6 in. The life expectancy of the inverter is 

20 years or greater. 

The GRC West Area 72 kW PV power system was designed per the National Fire Protection 

Association (NFPA) 70, the National Electrical Code (NEC). The system concurs with all articles of the 

NEC, and in particular addresses Article 690, Solar Photovoltaic Systems. In addition, the system was 

designed to be completely in concurrence with the NASA GRC Safety Manual. The PV panels meet the 

requirements of Underwriters Laboratories Standard for Safety UL-1703 concerning flat-plate PV 

modules and panels. The PV panels are fused to provide overcurrent protection. The PV panels, and the 

entire PV system, are bonded and grounded per the NEC. The PV inverter includes an NEC compliant 

DC and AC disconnect switch to provide complete system isolation whenever the disconnect switch is 

opened. The inverter is configured to automatically open the inverter circuits whenever utility power is 

lost to prevent power from the PV system from feeding back into the utility power system, thus 

preventing a potential safety hazard. 

Discussion 

The objective of designing the GRC West Area 72 kW grid-tied photovoltaic power system is to 

develop a photovoltaic power system that can be used for the testing of PV systems for research 

applications, and to provide power to the GRC utility grid when research is not being conducted that can 

be used by all. 

The predicted annual energy production from the 72 kW PV power system is 78,797 kWh, which is a 

realistic prediction based upon the test results from the GRC prototype 2 kW grid-tied PV power system 

(Ref. 4), and the GRC Visitor’s Center grid-tied PV power system (Ref. 5). The long-term system 

performance of GRC’s existing PV power systems provides confidence in the integrity of the design of 

the GRC West Area 72 kW PV power system. 

The rather large predicted monthly variation in energy production of the GRC West Area 72 kW PV 

power system shown in Figure 1 indicates the large seasonal variation in sunlight in Cleveland, Ohio. A 

grid-tied PV power system is advantageous in regions, such as Cleveland, in which utility power is 

essential in times of limited sunlight to meet the power requirements of the load. The significant power 

produced by the PV power system in the summer months is valuable in meeting the high utility system 

power demand at that time. 
NASA/TM—2009-216065 8 

The monthly energy production of the GRC prototype 2 kW PV power system over the past 

four years indicates very consistent long-term system performance (Ref. 4). No effort was made to clean 

the PV panels, or to clear them of snow for these tests. Providing cleaning and snow clearing of the PV 

panels would improve PV system performance, but the test results obtained without cleaning or snow 

clearing indicates the excellent performance attainable from this system under no maintenance conditions. 

No planned maintenance is required for the GRC West Area 72 kW PV power system. 

The GRC prototype 2 kW PV power system has provided consistent long-term PV system 

performance over the past four years with no system failures, no down time, and no required system 

maintenance (Ref. 4). Excellent system performance is predicted for the GRC West Area 72 kW PV 

power system as well. 

Concluding Remarks 

The NASA Glenn Research Center has successfully designed, developed, analyzed, and tested a 

prototype 2 kW DC grid-tied photovoltaic power system, and a 12 kW DC grid tied photovoltaic power 

system. A 72 kW DC grid-tied photovoltaic power system was designed for the GRC West Area Solar 

Field based upon the success of the existing grid-tied photovoltaic power systems. The goals of the 

project include reducing the Nation’s dependence on fossil fuels, and reducing the production of harmful 

emissions. The objective of this work is to develop a viable 72 kW DC grid-tied photovoltaic power 

system that can be used for GRC PV testing applications and to provide AC facility power for all times 

that PV research power is not required. The GRC West Area 72 kW grid-tied photovoltaic power system 

will validate the theoretical analyses, and verify long-term system performance. 

Theoretical analyses have been performed successfully to predict the energy produced by grid-tied 

PV systems in Cleveland, Ohio. Empirical test results obtained from the experimental hardware 

successfully validated the basic principles described, and the theoretical work that was performed. Of 

particular value, are the analytical tools and capability successfully used for this project. Performance 

predictions can be made confidently for grid-tied PV systems of various scale. 

The prototype 2 kW DC grid-tied PV system has provided consistent long-term performance over the 

past four years with no system failures, no down time, and no required system maintenance (Ref. 4). The 

GRC Visitor’s Center 12 kW DC grid-tied PV system has been equally successful for over one year 

(Ref. 5). From the analyses and empirical test results, it is apparent that grid-tied PV systems are viable in 

Cleveland, Ohio. 

The report concludes that the implementation of grid-tied photovoltaic power systems can provide 

significant improvements in power system performance, reduce dependency on fossil fuels, and reduce 

the production of harmful emissions. A GRC West Area 72 kW grid-tied PV system is a valuable tool for 

PV research for space and terrestrial applications, and is an efficient, reliable, and maintenance free 

source of power for GRC and the local community. 
NASA/TM—2009-216065 9 

Appendix—Equipment Summary Data Sheet 

Existing GRC West Area Solar Field Photovoltaic System 

1.0 Photovoltaic Panels 

1.1 Type Silicon Poly-Crystalline 

1.2 Nominal Power 43 W 

1.3 Max Power Voltage (Vmp) 17.3 V 

1.4 Max Power Current (Imp) 2.49 A 

1.5 Open Circuit Voltage (Voc) 21.7 V 

1.6 Short Circuit Current (Isc) 2.7 A 

1.7 Nominal Operating Cell Temp (NOCT) 47.0 °C (116.6 °F) 

1.8 Nominal Power at NOCT 39.1 W 

1.9 Max Power Voltage at NOCT 15.3 V 

1.10 Max Power Current at NOCT 2.56 A 

1.11 Open Circuit Voltage at NOCT 20.0 V 

1.12 Short Circuit Current at NOCT 2.77 A 

1.13 Short Circuit Current Temp Coefficient per Cell 2.0 mA/°C 

1.14 Open Circuit Voltage Temp Coefficient per Cell –2.5 mV/°C 

 1.15 Cell Area 3.61 sq ft 

 1.16 Cell Efficiency 12.8% 

 1.17 Module Efficiency 11.5% 

1.18 Width 30.5 cm (12.0 in.) 

1.19 Length 12.2 cm (48.0 in.) 

1.20 Depth 6.4 cm (2.5 in.) 

1.21 Weight 5.9 kg (13.0 lb) 
NASA/TM—2009-216065 10 

Proposed GRC West Area Grid-Tied Photovoltaic Power System 

1.0 Photovoltaic Panels 

1.1 Type Silicon Poly-Crystalline 

1.2 Peak Power (Wp) 200 W 

1.3 Max Power Voltage (Vmp) 27.1 V 

1.4 Max Power Current (Imp) 7.4 A 

1.5 Open Circuit Voltage (Voc) 34 V 

1.6 Short Circuit Current (Isc) 7.8 A 

1.7 Short Circuit Temp Coefficient 5.6 mA/°C 

1.8 Open Circuit Voltage Coefficient –0.12 V/°C 

1.9 Max Power Temp Coefficient –0.5%/°C 

1.10 Max Series Fuse 15.0 A 

1.11 Normal Operating Cell Temp (NOCT) 45.0 °C (113 °F) 

1.12 Width 98.1 cm (38.6 in.) 

1.13 Length 148.5 cm (58.5 in.) 

1.14 Depth 5.5 cm (2.2 in.) 

1.15 Weight 17.7 kg (39.0 lb) 

2.0 Source Circuit Combiner 

2.1 Type Parallel 

2.2 Number of Input Circuits 18 to 24 

2.3 Voltage Rating 600 VDC Continuous 

2.4 Current Rating 400 ADC Continuous 

2.5 Input Conductor Size No. 16 to 4 AWG 

2.6 Maximum Fuse Rating 20 A 

2.7 Number of Output Conductors 2 

2.8 Output Conductor Size No. 4 AWG to 350 MCM 

2.9 Enclosure Type NEMA 3R (outdoor rated) 

2.10 Width 50.8 cm (20.0 in.) 

2.11 Height 50.8 cm (20.0 in.) 

2.12 Depth 15.2 cm (6.0 in.) 

2.13 Weight 20.4 kg (45.0 lb) 
NASA/TM—2009-216065 11 

2.0 Inverter 

2.1 Type Three Phase Sine Wave 

2.2 Max AC Power Output 75000 W 

2.3 Maximum DC Input Voltage 600 VDC 

2.4 DC Peak Power Tracking Range 295 to 500 VDC 

2.5 DC Nominal Current 267 A 

2.6 Nominal AC Output Voltage 480 VAC 

2.7 AC Operating Voltage Range 422 to 528 VAC 

2.8 Nominal AC Frequency 60 Hz 

2.9 Max Continuous Output Current 90 A 

2.10 Max Total Harmonic Distortion 3% 

2.11 Power Factor 0.99 

 2.12 Peak Inverter Efficiency 95.5% 

 2.13 Standby Losses 42 W 

 2.14 Output Overcurrent Protection 25 A 

 2.15 Operating Temperature Range –30 to 50 °C (–22 to 122 °F) 

2.16 Enclosure Type NEMA 4 (outdoor rated) 

2.17 Disconnect PV/Utility disconnect 

2.18 Cooling Forced Convection 

2.19 Width 159.0 cm (62.6 in.) 

2.20 Height 234.7 cm (92.4 in.) 

2.21 Depth 88.9 cm (35.0 in.) 

2.22 Weight 1247.4 kg (2750 lb) 

 
NASA/TM—2009-216065 12 

References 

1. Smil, Vaclav, “Energy at the Crossroads: Global Perspectives and Uncertainties,” The MIT Press, 

November 1, 2003. 

2. Department of Energy, “U.S. Climate Change Technology Program: Technology Options for the Near 

and Long Term,” DOE/PI-0002, November, 2003. 

3. Mennicucci, David F., “Photovoltaic Array Simulation Models,” Solar Cells, 1986, pp. 383–392. 

4. Eichenberg, Dennis J., “Development and Testing of a Prototype Grid-Tied Photovoltaic Power 

System,” NASA/TM—2009-216062, 2009. 

5. Eichenberg, Dennis J., “Development and Testing of the GRC Visitor’s Center Grid-Tied 

Photovoltaic Power System,” NASA/TM—2009-215847, 2009. 
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Design of a Glenn Research Center Solar Field Grid-Tied Photovoltaic Power System 

5a. CONTRACT NUMBER

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6. AUTHOR(S)

Eichenberg, Dennis, J. 

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WBS 392259.02.03.0485.09 

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National Aeronautics and Space Administration 

John H. Glenn Research Center at Lewis Field 

Cleveland, Ohio 44135-3191 

8. PERFORMING ORGANIZATION

 REPORT NUMBER

E-17115 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration 

Washington, DC 20546-0001 

10. SPONSORING/MONITOR'S 

 ACRONYM(S)

NASA 

11. SPONSORING/MONITORING

 REPORT NUMBER

NASA/TM-2009-216065 

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified-Unlimited 

Subject Category: 44 

Available electronically at http://gltrs.grc.nasa.gov 

This publication is available from the NASA Center for AeroSpace Information, 443-757-5802

13. SUPPLEMENTARY NOTES

14. ABSTRACT

The NASA Glenn Research Center (GRC) designed, developed, and installed, a 37.5 kW DC photovoltaic (PV) Solar Field in the GRC 

West Area in the 1970s for the purpose of testing PV panels for various space and terrestrial applications. The PV panels are arranged to 

provide a nominal 120 VDC. The GRC Solar Field has been extremely successful in meeting its mission. The PV panels and the supporting 

electrical systems are all near their end of life. GRC has designed a 72 kW DC grid-tied PV power system to replace the existing GRC West 

Area Solar Field. The 72 kW DC grid-tied PV power system will provide DC solar power for GRC PV testing applications, and provide AC 

facility power for all times that research power is not required. A grid-tied system is connected directly to the utility distribution grid. 

Facility power can be obtained from the utility system as normal. The PV system is synchronized with the utility system to provide power 

for the facility, and excess power is provided to the utility for use by all. The project transfers space technology to terrestrial use via 

nontraditional partners. GRC personnel glean valuable experience with PV power systems that are directly applicable to various space 

power systems, and provide valuable space program test data. PV power systems help to reduce harmful emissions and reduce the Nation’s 

dependence on fossil fuels. Power generated by the PV system reduces the GRC utility demand, and the surplus power aids the community. 

Present global energy concerns reinforce the need for the development of alternative energy systems. Modern PV panels are readily 

available, reliable, efficient, and economical with a life expectancy of at least 25 years. Modern electronics has been the enabling technology 

behind grid-tied power systems, making them safe, reliable, efficient, and economical with a life expectancy of at least 25 years. The report 

concludes that the GRC West Area grid-tied PV power system design is viable for a reliable, maintenance free, long life power system that 

is of significant value to NASA and the community. 

15. SUBJECT TERMS

Photovoltaic conversion; Energy conversion; Electric power 

16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

 ABSTRACT

UU 

18. NUMBER

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18 

19a. NAME OF RESPONSIBLE PERSON

STI Help Desk (email:help@sti.nasa.gov) 

a. REPORT

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b. ABSTRACT

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c. THIS 

PAGE

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19b. TELEPHONE NUMBER (include area code)

443-757-5802 

Standard Form 298 (Rev. 8-98)

Prescribed by ANSI Std. Z39-18