A Loss Analysis for a 28% Efficient 520X Concentrator Module
A module efficiency loss analysis has been conducted by comparing the efficiency of the module on-sun (28.2% peak) to the efficiency of the bare cell measured in the laboratory (35.5% peak). This analysis suggests that there are two main loss mechanisms in the module: elevated operating temperature and an optical efficiency less than unity. This analysis also suggests that the effects of spectral and intensity non-uniformity have been well controlled
The effect of temperature on the efficiency of concentrator PV modules with MJ SC
Presented is a method for calculating the power-productivity of photovoltaic (PV) installations with sunlight concentrators and multijunction (MJ) solar cells (SC) allowing for variation of their power efficiency in dependence on real operation conditions - spectral composition and sunlight flux density and also on temperature of multijunction cells. The yearly totals of specific electric power generated by a module at constant and variable efficiency values have been calculated. It has been shown that allowing for the joint effect of the sunlight characteristics and multijunction SC temperature on the photovoltaic module efficiency must be realized in simulating the module operation in any power generating systems. These allows excluding the overestimations of the yearly power totals generated by a solar installation in determining the power productivity.
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.