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Title: Large scale production task: low cost silicon solar array project. Final technical report

Abstract

Several design concepts were evaluated and compared with respect to potential for low cost and automation, protection against weathering, potential for array efficiency as a function of weight and area, potential for design flexibility and exposure to electrical breakdown or leakage to ground. This evaluation program narrowed attention to design concepts involving glass as the primary structural and weather resistant component of the module. The leading specific design structure consisted of the solar cell circuit embedded in polyvinyl butyrate by lamination between a glass front surface and a polyester film rear surface. Preliminary evaluation of this structure in high humidity and thermal cycle was promising, and extensive field experience with similar structures in architectural and automotive applications was favorable. The specific design proposed was comprised of 120 two-inch diameter cells in a series-parallel configuration. The laminate was mounted in an aluminum frame with a neoprene gasket providing the requisite mechanical strength with flexibility. The resulting module size of 15 by 46 inches permits three modules to be neatly fitted into the 46 inch square subarray specified by JPL. The design as modified to accommodate subsequent experience is shown. Performance and environmental test results are presented and discussed.

Publication Date:
Research Org.:
Spectrolab, Inc., Sylmar, CA (USA)
OSTI Identifier:
5927802
Report Number(s):
DOE/JPL/954587-1
DOE Contract Number:
NAS-7-100-954587
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; SILICON SOLAR CELLS; DESIGN; PERFORMANCE; SOLAR CELL ARRAYS; CONNECTORS; ELECTRIC CONTACTS; ENCAPSULATION; FABRICATION; GLASS; HUMIDITY; LAMELLAE; PERFORMANCE TESTING; POLYVINYLS; PRODUCTION; TEMPERATURE DEPENDENCE; TESTING; THERMAL CYCLING; THERMOPLASTICS; WEATHERING; CONDUCTOR DEVICES; DIRECT ENERGY CONVERTERS; ELECTRICAL EQUIPMENT; EQUIPMENT; ORGANIC COMPOUNDS; ORGANIC POLYMERS; PETROCHEMICALS; PETROLEUM PRODUCTS; PHOTOELECTRIC CELLS; PHOTOVOLTAIC CELLS; PLASTICS; POLYMERS; SOLAR CELLS; 140501* - Solar Energy Conversion- Photovoltaic Conversion

Citation Formats

Not Available. Large scale production task: low cost silicon solar array project. Final technical report. United States: N. p., 1978. Web. doi:10.2172/5927802.
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Not Available. Large scale production task: low cost silicon solar array project. Final technical report. United States. doi:10.2172/5927802.
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Not Available. Fri . "Large scale production task: low cost silicon solar array project. Final technical report". United States. doi:10.2172/5927802. https://www.osti.gov/servlets/purl/5927802.
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@article{osti_5927802,
title = {Large scale production task: low cost silicon solar array project. Final technical report},
author = {Not Available},
abstractNote = {Several design concepts were evaluated and compared with respect to potential for low cost and automation, protection against weathering, potential for array efficiency as a function of weight and area, potential for design flexibility and exposure to electrical breakdown or leakage to ground. This evaluation program narrowed attention to design concepts involving glass as the primary structural and weather resistant component of the module. The leading specific design structure consisted of the solar cell circuit embedded in polyvinyl butyrate by lamination between a glass front surface and a polyester film rear surface. Preliminary evaluation of this structure in high humidity and thermal cycle was promising, and extensive field experience with similar structures in architectural and automotive applications was favorable. The specific design proposed was comprised of 120 two-inch diameter cells in a series-parallel configuration. The laminate was mounted in an aluminum frame with a neoprene gasket providing the requisite mechanical strength with flexibility. The resulting module size of 15 by 46 inches permits three modules to be neatly fitted into the 46 inch square subarray specified by JPL. The design as modified to accommodate subsequent experience is shown. Performance and environmental test results are presented and discussed.},
doi = {10.2172/5927802},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Sep 01 00:00:00 EDT 1978},
month = {Fri Sep 01 00:00:00 EDT 1978}
}
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Technical Report:
View Technical Report (0.99 MB)
DOI:  10.2172/5927802
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  • Forty kilowatts of solar cell modules was produced in this program. This is equivalent to 4123 modules. The average power output per module was 9.7 watts at 16.5 volts, 60/sup 0/C and 100 mW/cm/sup 2/. The peak production rate was 200 modules per week which is equal to 1.9 kW per week. This rate was sustained for over four and one-half months and is equivalent to 100 kW per year. The solar cell module design, electrical and power performance, module preproduction environmental test results, production and shipping schedule, program summary, and delivery are described. A cost analysis section is written.more » Particular emphasis on the percentage of labor and material utilized in constructing a solar cell module is presented. Also included are cost reduction recommendations. It was concluded from this program that volume production on the order of hundreds of kilowatts per year per company as a minimum is required to significantly reduce the price per watt for solar cell modules. Sensor Technology more than doubled its solar cell module manufacturing facilities since the completion of the JPL Block II procurement. Plans are being made for large scale expansion of our facilities to meet growing JPL/DOE procurements.« less

  • Through this contract, and the cooperative program resulting from the JPL-ERDA-NASA Low Cost Silicon Solar Array Project, Sensor Technology has produced modules at the rate of 3.5 KW per month with a power output of 83.2 watts per 4' x 4' array. These modules were produced at a cost of $19.07 per watt. The production techniques of this program make it easily possible to expand this to the 10 to 15 KW per month range and methods were developed by which future costs may be reduced by 15 to 30%. Two inch diameter cells were used on this project, however,more » facilities now exist to process 3 inch, 3.56 inch and 4 inch diameter wafers. The module design, performance, cost factors, problem areas, efficiency, encapsulation, and humidity and temperature test results are reported.« less

  • 2000 solar power modules capable of producing over 10 kW of peak power were delivered by Spectrolab, Inc., during the period March to October 1976. These modules were comprised of twenty 2-inch diameter silicon solar cells embedded in a silicone elastomeric potting compound on an aluminum T beam extrusion with a glass cover plate and were typical of standard commercial products being manufactured during that time period. These modules have good structural and thermal dissipation characteristics, but difficulties were encountered with respect to delamination of the encapsulant material, low electrical breakdown resistance and humidity sensitivity. The extensive environmental test programmore » and subsequent analytical analysis of results has provided a great deal of new knowledge of the module design. It has shown there were many limitations with this particular commercial module which were not known at the start of the program and should provide a good basis for developing an improved module in the future. Design modifications that have been recommended to improve reliability and reduce cost, include the elimination of metal substrate, replacement of silicone with a more suitable encapsulant, larger module size and use of series-parallel circuit configurations.« less

  • ;
    Bar specimens were cut from ingots of single crystal silicon, and acid-etched prior to testing. Artificial surface flaws were introduced in specimens by indentation with a Knoop hardness tester. The specimens were loaded in four-point bending to 95% of the nominal fracture stress, while keeping the surface area, containing the flaw, wet with test liquids. No evidence of delayed fracture, and, therefore stress corrosion, of single crystal silicon was observed for liquid environments including water, acetone and aqueous solutions of NaCl, NH/sub 4/OH, and HNO/sub 3/, when tested with a flaw parallel to a (110) surface. The fracture toughness wasmore » calculated to be K/sub IC/ = 0.591 x 10/sup 6/ N/m/sup 3/2/.« less

  • ; ;
    Results of an experimental program investigating the hot workability of polytextuerystalline silicon are reported. Uniaxial stress-strain curves are given for strain rates in the range of 10/sup -5/ to 10/sup 1/ sec/sup -1/ and temperatures from 1100 to 1380/sup 0/C. At the highest strain rates at 1380/sup 0/C axial strains in excess of 20% were easily obtainable without cracking; although special preparation of the compression platens allows strains in excess of 50%. After deformations of 36%, recrystallization is completed within 0.1 hr at 1380/sup 0/C. When the recrystallization is ''complete,'' there is still a small volume fraction of unrecrystallized materialmore » which appears very stable and may degrade the electronic properties of the bulk material. Texture measurements show that the as-produced vapor deposited polycrystalline rods have a <110> fiber texture with the <110> direction parallel to the growth direction and no preferred orientation about this axis. Upon axial compression perpendicular to the growth direction the former <110> fiber axis changes to <111> and the compression axis becomes <110>. Recrystallization changes the texture to <110> along the former fiber axis and <100> along the compression axis.« less