Costs The basis used herein was to work from the ERDA effort to develop high volume, low cost silicon cells for terrestrial applications. The ERDA program will achieve a high volume production by 1985 of 10% (AMI) solar cells at a cost of $500/Kw. The SPS program will be able to build from the ERDA work and have approximately ten additional years to pursue the solar cells necessary for the SPS. It therefore seems probable that with the additional ten years to pursue high efficiency improvements that $500/Kw for the SPS is a reasonable goal for which to strive. If the ERDA goal can be achieved ty 1985, a high probability exists that the SPS goal can also be met. Technology Status Current Technology Solar Array Blanket - Over the past several years much work has been done in this country toward development of flexible substrate, lightweight solar arrays. Early hardware in those development programs weighed on the order of 1.7 Kg/M^. These arrays used Kapton, fiberglass and other materials being considered in the context of the SPS. The solar cells were 200-300 uM thick and used soldered interconnect systems. Some of the designs did not use the laminated interconnect system being referenced herein. The latest versions of this hardware being developed within NASA weighs less than 1 Kg/M^ and makes use of cells which are 200 pM thick. Also, they use 12.5 UM thick Kapton (presently thinnest available). As can be seen in the weight table (Table IV-B-l-b-1), the major effort in weight reduction achievement will of necessity come from the use of a thin solar cell and cover. It is felt that the work going on in continuous thick film single crystal silicon solar cells offers hope of achieving a 100 jjM cell for this application. Probably, however, special emphasis will be necessary to guide the goals of such a program to also meet the high efficiency needed. The efficiency achievement, which will need to be interlocked with the high volume production of thin cells, are being pursued presently in both private and government labs. Work invoving wraparound contacts, spray-on contacts, integral covers and the like all are making significant progress today. This gives confidence that with proper guidance the next 15 to 20 years can realize the necessary achievements. An area where work must be initiated is in the area of concentrator development. If the achievable reflectivity is considerably lower than reference, a more complex geometry for the reflector will be necessary (or more solar blanket added). In addition, the lifetime in orbit and surface quality relationships must be developed. This can only be done through in-space flight experiments. The determination of thermal cycling degradation also must be pursued. A certain body of analytical work has been done which can be coupled
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