The PV industry currently services a wide range of terrestrial applications, from power for small consumer products to larger grid-connected systems. III-V solar cells are currently too expensive for most one-sun applications. While satellites represent an example of an application for which the extra cost is acceptable, for bulk electricity generation, a concentration of 400 suns or greater may be needed to achieve an acceptable cost. Multiple companies have now implemented multijunction III-V cells into terrestrial concentrator systems. Concentrator cells and systems are discussed in detail in Chapter 10.
Use of GaInP/Ga(In)As/Ge cells in high-concentration systems (500x and above) has the potential of generating electricity at 7 cents/kWh . The price of multijunction solar cells has been reported to be as low as $24 M for 105 MW, or $0.23/W (http://cleantech. com/news/1713/emcore- gets-24m-purchase-order). The current space-cell production capacity of ~1 MW/yr translates into a 1000x concentrator cell production capacity of ~1 GW/yr. The high efficiency, the projected low cost, and the ease with which production of concentrator cells could be initiated with existing production equipment make terrestrial applications attractive for these cells. As the champion efficiencies of these cells have increased, the interest in using these in concentrator systems for terrestrial electricity generation has grown impressively. The specific issues associated with development of concentrator solar cells are discussed below.