Durability of dielectric fluids for concentrating photovoltaic systems

Several dielectric fluids that might be used for immersing optics are analyzed in this paper. Their transmittances, both before and after an accelerated exposure to ultraviolet (UV) radiation equivalent to several years under real sun, are presented. In addition, the photocurrent losses caused by the decrease in transmittance experienced by each fluid are estimated for current III–V multijunction (MJ) solar cells. The most stable fluids were found to be paraffin and silicone oils whose transmittances remained practically unaltered after a UV dosage equivalent to 3 years of AM1.5D radiation.

► A comparison of fluid candidates to be used in concentrating photovoltaic systems is presented.
► Fluids for immersing optics have been tested in a accelerated UV degradation chamber.
► Fluids containing OH bonds are discarded to be use with multijunction solar cells.
► Paraffin oil withstands an accelerated UV degradation test equivalent to 3 years outdoors.