Output energy predictions for hybrid concentrator III-V / planar thin-film modules

This paper evaluates annual energy delivery from a Solar PhotoVoltaic Installation (SPVI) based on most advanced III-V CPV technology combined with a conventional thin-film flat-plate concept. The goal of the proposed integration was to capture both direct and diffuse sunlight in one module, increasing efficiency in PV conversion of global solar radiation. A hybrid module contained silicone-on-glass Fresnel lenses and an electrogenerating board with both small-size high efficiency concentrator GaInP/Ga(In)As/Ge triple-junction SCs and planar α-Si/nc-Si dual-junction units. The last ones covered free space around concentrator SCs. Daily/monthly solar energy income and hybrid module electricity production were estimated at 3 typical climatic zones differing by amount of clear days in a year. For specific locations of SPVIs, the characteristic factors leading to variation of the direct and scattered (diffuse) solar radiation proportions in the daytime with corresponding change in the total energy production were taken into account. Basing on the data obtained on the incoming radiation, the IV characteristics of the modules were simulated, and dependence of their efficiency and total annual energy output coming from concentrator as well as planar parts of the module were investigated. In the simulating, a three-dimensional equivalent circuit with distributed parameters, which allows considering nonlinear resistive losses in SCs and modules, was used. It was shown that thin-film units effect on the overall power productivity is 6–8 % depending on a geographic region and that, when the sky was cloudy, the share of generated power by these cells could be increased temporarily up to 10%.