Improving Photovoltaic Module Efficiency Using Back Side Water-Cooling Technique

Low energy conversion efficiency of a solar photovoltaic module is a major issue that prevents people from using this technology. One of the major causes of low efficiency is the high operating cell temperature of the PV panel. It causes the occurrence of current mismatch and hotspot problems that not only degrade the overall performance of the module but also permanently damage the cell due to thermal stress. In this paper, an experimental study has been conducted to investigate the effect of cooling on the efficiency of mono-crystalline and poly-crystalline photovoltaic modules. A backside water cooling piping model is used in the experiment. Copper pipes are bend in an elliptical shape and thermally bonded at the backside of photovoltaic panels that act as a heat exchanger. The thermal conductivity of copper is around 385 W/m-K which is comparatively high to other useable metals. The advantage associated with specific elliptical shape copper pipe cooling model induction is that the temperature gradient across the panel becomes lower. Water is used as a working fluid with a mass flow rate of 0.052 L/sec. The experimental setup is arranged and performed in the month of august at NUST University, Islamabad. The ambient temperature at which the experiment conducted was about 40° C. With active water cooling, the results obtained after the induction of the cooling model with experimental measurements are quite impressive. The PV module temperature is dropped significantly to around 12° C. Under this experimental setup, the monocrystalline PV module performs comparatively better than the polycrystalline PV module after the induction of the cooling model. Experimental values show that the monocrystalline PV module leads by an increase in efficiency by 4.46 % and the polycrystalline PV module leads to an increase in efficiency by 3.45%.