Thermal characterization of a silicone-on-glass micro aspheric lens array for a concentrator photovoltaic module

This study examined the effects of the thermal deformation of a silicone-on-glass (SOG) micro aspheric lens on the optical performance of a concentrator photovoltaic (CPV) module. Thermal deformation of the lens induced by temperature variation causes defocalization of the spot of concentrated light on the solar cell, resulting in a change in the optical efficiency and irradiance uniformity in the solar cell area. The irradiance uniformity affects the fill factor of the solar cell. The effects of the thermal deformation of the lens on the optical efficiency and irradiance uniformity in the solar cell area were evaluated through a three-dimensional thermal deformation simulation and ray-tracing simulation. The simulation methods were validated by indoor heating tests using a prototype SOG lens and III–V triple-junction solar cell. The simulation results for optical systems with geometric concentration ratios of 200 × and 500 × revealed that the temperature dependences of the optical performances of a system with SOG micro aspheric lenses showed similar trends to those of a system with SOG Fresnel lenses designed with the same lens surface profiles as aspheric lenses.