Humidity control in planar micro-tracking CPV modules by means of passive solutions

CPV modules mostly contain air between lenses and cells that due to the water vapor content can end up condensing, being a potential problem not only of reliability of the interior components but also affects the transmissibility of the optical stage and therefore reduces energy yield. Among the passive humidity control options, the use of desiccants, the use of breathers and the formation of controlled condensation have been identified. On the one hand, the dynamic response of molecular sieves, zeolites and silica gel has been tested, showing that silica gel has a higher adsorption/desorption capacity than the rest. On the other hand, breathers based on Gore membrane and labyrinth structure have been compared, the latter having the best breathability. Finally, the suitability of using controlled condensation to prevent condensation from forming in the lens area has been validated. The procedure is based on the radiative cooling experienced by lenses exposed to the night sky, by using materials with higher emissivity in the spectral range of the atmospheric window.