ABSTRACT
FAE (fotovoltaico ad alta efficienza/high-efficiency photovoltaic) is an experimental high-concentration photovoltaic and thermal (HCPV/T) module. Solar radiation is concentrated on InGaP/InGaAs/Ge triple-junction cells by off-axis parabolic mirrors, with a nominal factor of ~2,000 suns. A glass frustum is glued on the triple-junction cell and acts as secondary optics. The full module consists of 20 cells equipped with the secondary frustum and integrated into an active heat sink, which is designed to minimize thermal resistance. Primary mirrors and cell receivers are reciprocally fixed and mounted on an Alt-Azimuth two-axis tracker. The N–S primary rotational axis is bearing ten couples of mirrors and receivers whose secondary E–W axes are moved via a parallelogram transmission by a linear actuator. The tracking control systems include an “open-loop” algorithm and a “closed-loop” that corrects installation inaccuracies and mechanical tolerances. The extracted thermal energy results close to 50% of the incident direct normal irradiance (DNI), while the electrical efficiency is about 30%, contributing to a total combined efficiency of about 80%. The field experience has shown some limits of the system due to the extreme sensitivity to the tracking accuracy and the relative complexity of the cooling circuit. A strategy toward the simplification and industrialization of the module has been envisaged, which takes into account the application of optical fibers.
