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U.S. Department of Energy
Office of Scientific and Technical Information

Photovoltaic field test performance assessment. Technology status report No. 4. Final report

Technical Report ·
OSTI ID:6076031

Descriptions of 1984 performance are provided for five fixed-tilt flat plate, one tracking flat plate, and two concentrator photovoltaic systems. They range in size from 18 kW to 1000 kW. All of the systems have extensive instrumentation; performance readings are generally available every 10 minutes. Installations vary in energy efficiency. The older, fixed-tilt, flat plate sites have the lowest efficiency (5%). Next are the newer flat plate sites of both fixed-tilt and tracking types (6 to 7%). The Fresnel lens concentrator sites have the highest efficiency (6 to 9%). Installations vary widely in availability. Power conditioning unit failure is the largest contributor to decreased availability. In general, nameplate ratings are optimistic. Observed power output equals these ratings only under rare combinations of high insolation and low ambient temperature. Degradation in energy efficiency may be occurring at Oklahoma City. The tracking flat plate site demonstrates high energy capture and capacity factor. The Fresnel lens concentrators are especially sensitive to tracking error and cloudiness. At flat plate sites that have monocrystalline silicon cells, energy efficiency is fairly constant with insolation. At flat plate sites using polycrystalline cells, energy efficiency increases with insolation. At the Fresnel lens concentrator sites (both using monocrystalline cells), energy efficiency increases with insolation. Problems, mostly of the hardware type, with the on-site data acquisition system continue to hinder data collection.

Research Organization:
Boeing Computer Services Co., Tukwila, WA (USA). Engineering Technology Applications Div.
OSTI ID:
6076031
Report Number(s):
EPRI-AP-4466; ON: TI86920226
Country of Publication:
United States
Language:
English