Cooling systems

The efficiency of PV modules is discussed with particular care to the problem of thermal drift. Cooling system is suggested as a method to improve the PV modules efficiency and water veil and water spray are analysed.The gain in efficiency is due to two mechanisms: the lowering of the PV module temperature which ranges between 6% and 12% depending on the irradiation condition and the minor reflectance of the PV module due to the presence of the water veil which has a refraction index intermediate between glass and air. This last effect account from a gain ranging from 2% to 4% depending on the light incidence angle.The water spray is discussed together with the possibility of cooling the panel with spray on its rear, without affecting the active surface. Experimental finding are discussed.Finally the impact of cooling on lifetime of the PV module is discussed and positive results are obtained thanks to the reduction of the thermal shocks.