Design and development of a 300-watt solar photovoltaic concentrator. Final report
The design, fabrication, and performance of high level concentration (300X) with refractive lenses on small silicon solar cells approx. (0.4 cm/sup 2/) with passive cooling are described. Four systems were fabricated using polar axis (2-axis) tracking. Two systems were rated at 100 W peak, and two were rated at 300 W peak. The maximum power measured on the 300-W unit was 236 W at 93 mW/cm/sup 2/ direct insolation. Solar cells were designed and fabricated using bulk high resistivity n-type silicon which showed a maximum efficiency of 17.5% independent of concentration level from 50 to 400X. At 1000X, the efficiency dropped to 14%. Lens arrays made from vacuum formed shells and epoxy filled showed good performance on a selected basis but nonuniformity and uv degradation dictated a change to Fresnel lenses. The Fresnel lens arrays are approximatley 83% efficient but the imaging was quite nonuniform causing degradation in cell fill factor and collection efficiency. Heat transfer calculations and simulations show that the cell temperature is about 25/sup 0/ to 35/sup 0/C above ambient temperature. The motion of the system is polar axis rotation with panels tilting within that axis for seasonal adjustments. The daily motion is clock driven with addition or deletion of clock pulses controlled by a solar sensor and logic circuits. Seasonal tilt is provided by an analog drive controlled also by a solar sensor. The unit is mounted on a pair of tripods anchored to ground with augers. An optimization analysis was performed on passively cooled photovoltaic concentrators showing the various tradeoffs that exist with lens size and concentration level. The conclusions are that minimum manufacturing costs of $0.70/peak watt can be obtained at an optimum lens size of approximately 100 cm/sup 2/ and concentration level of 100 suns. Deviation from this optimum either degrades performance, increases cost,or both.
- Research Organization:
- RCA Labs., Princeton, NJ (USA). David Sarnoff Research Center
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6273985
- Report Number(s):
- SAND-78-7027
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FRESNEL LENS
DESIGN
PERFORMANCE
SILICON SOLAR CELLS
SOLAR CONCENTRATORS
COOLING SYSTEMS
FABRICATION
FILL FACTORS
HEAT SINKS
HEAT TRANSFER
OPTIMIZATION
SOLAR TRACKING
DIRECT ENERGY CONVERTERS
ENERGY TRANSFER
LENSES
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
SOLAR CELLS
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