Line-focus optics for multijunction cells in space power arrays

Since 1986, ENTECH has been developing lightweight, high-performance Fresnel lens optics for space photovoltaic concentrator systems. This development work has been technically and financially supported by NASA-Lewis, SDIO, BMDO, Boeing, JX Crystals and AEC-ABLE. A fully functional experimental mini-dome Fresnel lens concentrator solar cell array was onboard the PASP Plus mission launched in August 1994. This array, assembled by Boeing using mechanically stacked multijunction (MSMJ) solar cells, confirmed the high-performance and low-radiation-degradation characteristics predicted for the refractive concentrator approach. Since PASP Plus, ENTECH has developed a line-focus Fresnel lens offering much improved manufacturability, cost, and sun-pointing error tolerance. This paper presents the latest line-focus optical designs customized for use with MSMJ cells and with monolithic multijunction (MMJ) cells.