Heat pipe cooling of concentrating photovoltaic cells

Concentrating photovoltaic systems (CPV) utilize low cost optical elements such as Fresnel lens or mini-reflecting mirrors to concentrate the solar intensity to 200 to 1000 suns. The concentrated solar energy is delivered to the solar cell at up to 20 to 100 W/cm². A portion of the energy is converted to electricity, while the portion that is not converted to electricity must be dissipated as waste heat. Solar cell cooling must be an integral part of the CPV design, since lower cell temperatures result in higher conversion efficiencies. Heat pipes can be used to passively remove the high heat flux waste heat at the CPV cell level, and reject the heat to ambient through natural convection. This paper discusses a cooling design that uses a copper/water heat pipe with aluminum fins to cool a CPV cell by natural convection. With a cell level waste heat flux of 40 W/cm², the heat pipe heat sink rejected the heat to the environment by natural convection, with a total cell-to-ambient temperature rise of only 40°C.