Booster reflectors for photovoltaic modules at high latitudes

The paper gives an analysis of the performance of the photovoltaic modules with planar booster reflectors with variable length and tilts for Swedish conditions. The principal difference between using modules with crystalline silicon cells or modules with thin film cells or amorphous silicon cells is discussed and numerical examples are given. If thin film or amorphous silicon modules are aligned with its cells extending from the reflector, the cells which are connected in series in the module always obtain the same average irradiance. Reflectors of a shorter length can therefore be used compared to a design with crystalline silicon modules where the whole module has to be evenly illuminated for maximum efficiency. It is shown that a stationary flat booster reflector can increase the module output in the order of 20-30%. Of special interest is the use of reflectors above the modules. With such designs the winter output can increase with 50% and a more even annual system output is achieved compared to systems with PV modules without reflectors.