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In this paper, two generic photovoltaic (PV) panels (poly-Si and mono-Si) were experimentally tested in typical Mediterranean climatic conditions. The focus of the applied experimental approach was to examine the effect of backside convective thermal profile and its impact on temperature distribution, i.e. on panel electrical efficiency. Therefore, a series of measurements was made in 2015, from April to July, as well as CFD modeling in order to obtain a detailed analysis of the possible working regimes. According to the obtained experimental and CFD results, the present design of typical PV panels have an unfavorable impact on PV panel electrical efficiency. Namely, typical contemporary panel designs lead to two typical backside convective air temperature profiles which have a direct impact on the effectiveness of natural cooling. As shown in the obtained measurements, the specific convective profiles at the backside of PV panels have a significant influence on the degradation rate of panel electrical efficiency in the estimated amount of 2.5% up to 4.5%. The results of the research discussed in this paper signal the need to provide a possible redesign of the backside surface in conventional PV panels, in order to increase their average efficiency (more efficient backside thermal dissipation). [ABSTRACT FROM AUTHOR]

This paper presents an alternative cooling technique for photovoltaic (PV) panels that includes a water spray application over panel surfaces. An alternative cooling technique in the sense that both sides of the PV panel were cooled simultaneously, to investigate the total water spray cooling effect on the PV panel performance in circumstances of peak solar irradiation levels. A specific experimental setup was elaborated in detail and the developed cooling system for the PV panel was tested in a geographical location with a typical Mediterranean climate. The experimental result shows that it is possible to achieve a maximal total increase of 16.3% (effective 7.7%) in electric power output and a total increase of 14.1% (effective 5.9%) in PV panel electrical efficiency by using the proposed cooling technique in circumstances of peak solar irradiation. Furthermore, it was also possible to decrease panel temperature from an average 54 °C (non-cooled PV panel) to 24 °C in the case of simultaneous front and backside PV panel cooling. Economic feasibility was also determined for of the proposed water spray cooling technique, where the main advantage of the analyzed cooling technique is regarding the PV panel’s surface and its self-cleaning effect, which additionally acts as a booster to the average delivered electricity. [ABSTRACT FROM AUTHOR]