Efficiency improvement of photovoltaic modules via back surface cooling

Crystalline silicon photovoltaics are a cardinal and well-consolidated technology for the achievement of energy efficiency goals, being installed worldwide for the production of clean electrical energy. However, their performance is strongly penalized by the thermal drift, mostly in periods of high solar radiation where solar cells reach considerably high temperatures. To limit this aspect, the employment of cooling systems appears a promising and viable solution. For this purpose, four different cooling systems, working on the photovoltaic (PV) panel back surface, were proposed and investigated in an experimental set-up located at the University of Calabria (Italy). Hourly electrical output power and efficiency were provided accounting for different meteorological conditions in several months of the experimental campaign. The results demonstrated that a simple spray cooling technique can provide an absolute increment of electrical efficiency of up to 1.6% and an average percentage increment of daily energy of up to 8% in hot months. More complex systems, based on ventilation or combining spray cooling and ventilation, were demonstrated not to be a viable option for PV performance improvement.