Experimental performance investigation of uniform and non-uniform cooling techniques for photovoltaic systems

Uniform cooling of photovoltaic (PV) panels is one of the key parameters to optimize the cell efficiency. Temperature non-uniformity on the surface of PV panel has a major affect on the global performance of PV systems and directly increases cell resistance which leads to a drop in the output of the system. In this paper, an experimental performance investigation has been carried out for non-uniform and uniform cooling techniques for PV panels subjected to the climate of Saudi Arabia. A uniform cooling technique for PV panels based on impingement cooling device is proposed to eliminate non-uniform heat transfer across the surface of the PV panel and its performance is compared with a conventional rectangular channel heat exchanger(RHX).The PV string's overall performance was found to be sensitive with the thermal characteristics of the system. Measurements showed cell temperature as high as 83°C for PV string without cooling. By employing impingement cooling, cell temperature was reduced to 37.1°C whereas conventional heat exchanger reduced it to 47.4°C. Conversion efficiency was enhanced by 98.4 % for impingement cooling and 60.6 % for heat exchanger cooling. Results reveal that impingement cooling has not only increased the electrical power output and conversion efficiency but has reduced the cell temperature while keeping it uniform for each cell.