Infra-red transmissive mirrors for concentrated photovoltaics

Concentrating photo-voltaic (CPV) technologies utilize mirrors or refractive optics such as Fresnel lenses to concentrate sunlight onto photovoltaic cells to generate electricity. Metal vapor coated mirrors have the disadvantage of reflecting far infra-red light onto the photovoltaic cell which is not converted into electricity, but does contribute to overheating of the photovoltaic cell. Since photovoltaic cell efficiencies are adversely effected by higher temperatures, thermal management designs are typically incorporated into CPV designs to remove excess heat. Expensive thermal management designs can be avoided, or minimized, with the use of infra-red transmissive mirror films made with dielectric interference stacks of polymeric materials. IR transmissive mirror films can be made with reflection band edges that correspond to the absorption band edge of any photo-voltaic cell material and thus re-direct non-useful far IR light away from the PV cell to avoid over heating.