Design and performance evaluation of a Micro-CPV system for building integration applications

The present research aims at developing a micro-CPV system with static optical elements designed to be placed at the exterior side of buildings to maximize building integration features. The optical system is formed by two optical media with differentiated Abbe number that are designed to minimize field curvature and chromatic aberrations to allow solar tracking by micro-movements of the PV receiver on a plane. An improved simultaneous multiple surface method has been applied to ensure that Fermat principle is met in all the interfaces of the optical system. The optical design angle of incidence range has been set from −40° to 40°. The maximum optical efficiency achieved has been ∼ 80 %. For and extended angular range of ± 70°, the system still operates but with an optical efficiency of ∼ 45 %. The system is intended to be integrated as a semitransparent glazing element allowing the diffuse irradiance to enter the building interior spaces for illumination purposes and the direct irradiance fraction to be concentrated onto the photovoltaic cells. Annual electricity production of 229 kWh/year has been obtained for 1 m² aperture area system, placed as a part of a typical residential building in Barcelona (Spain).