Technical and economic effects of cooling of monocrystalline photovoltaic modules under Hungarian conditions

This paper focuses on the impact of sprinkling and refrigerant based cooling methods of photovoltaic modules on actual performance, the duration of cooling and the quickness of the impact of cooling in comparison with monocrystalline photovoltaic modules without cooling. The obtained findings were analysed both from technical and economic aspects. Based on the parameters of the regression model used in this study (r=0.61), it can be concluded that a 1 degrees C increase of air temperature in the examined range (18-29 degrees C) improves actual performance by 1.58 W and cooling is probably necessary at higher temperatures. On more cloudy days, the expected performance is 9.8 W lower on average (P=0.001). In both experiments, there was an obvious negative correlation between module temperature and actual performance under constant radiation conditions. On more sunny days, one unit change in temperature resulted in a performance change of 1.2-1.3% (R-2=0.87-0.95), while more cloudy days resulted in less close correlation and a much lower change of temperature (0.8-0.9%) (R-2=0.70-0.81). The following conclusions can be drawn in relation to the two examined cooling methods: The actual performance of the sprinkling method is higher than that of the other two alternatives (by 19% and 25% in the case of the control method and by 13% and 18% in the case of refrigerant based cooling, depending on the day of measurement). After deducting the electricity needed for sprinkling cooling, the electric performance was still 12% better on average, using 22.5 L water per day on average. In the case of the refrigerant based cooling method, the produced extra energy was less than the electricity need of the heat exchanger itself; therefore, this method obviously seems to be unviable both from energetic and economic aspects. (C) 2016 The Authors. Published by Elsevier Ltd.