Performance investigation of photovoltaic modules by back surface water cooling

The temperature of the photovoltaic module has an adverse effect on the performance of photovoltaic modules. The photovoltaic module converts a small portion of energy from solar radiations into electricity while the remaining energy wastes in the form of heat. In this study, water cooled photovoltaic/thermal system was analyzed to enhance the efficiency by absorbing the heat generated by the photovoltaic modules and allowing the photovoltaic module to work at comparatively low temperature. For this system, four photovoltaic modules of two different types were used. To investigate the cooling effect, two modules were modified by making ducts at their back surface having inlet and outlet manifolds for water-flow. The measurements were taken with cooling and without cooling of photovoltaic modules. The temperature was measured at inlet, outlet, and at different points at the back of photovoltaic modules. It was found that there was a linear trend between the module efficiency and temperature. The average module temperature of c-Si and p-Si modules without cooling was 13.6% and 7.2% lower, respectively, than the same modules without cooling. As a result of temperature drop, the average module electrical efficiency of c-Si and p-Si was 13% and 6.2% higher, respectively, compared to the modules without cooling. Flowing water also gains useful heat from photovoltaic module so the resultant overall energy of the system was much higher.