Comprehensive analysis and general economic-environmental evaluation of cooling techniques for photovoltaic panels, Part II: Active cooling techniques

This paper deals with active cooling techniques for photovoltaic panels (PVs) where a detailed review was obtained as well as analysis by examining the findings of existing literature. Based on the obtained review, an elaboration of the main performance parameters was obtained for each specific considered coolant (air, water or nanofluids). It was found that the less investigated cooling techniques are the ones related to CPV (Concentrated Photovoltaic) systems and only a few studies exist with nanofluids as the considered coolant. The majority of tested active cooling options are based on water as the coolant and for PV/T (Photovoltaic/Thermal) configurations. The economic and environmental aspects of the active cooling techniques were not analysed in the majority of research studies thus there is an obvious gap in the existing literature. Therefore, the main outcomes of the herein obtained research are reflected through summarized analysis of all important aspects related to active cooling options for PV applications (performance, economic and environmental). According to the obtained results, the highest increase in PV panel performance is achieved by water base cooling techniques and they range from about 10% to 20% on average. To analyse economic and environmental aspects, a 30 kW PV system was studied as a case study. Regarding the economic aspect, the LCOE (Levelized Cost of Electricity) for the considered case study of a 30 kW PV system ranged from 0.096 €/kW h to 0.159 €/kW h. For the given circumstances, it was found that the considered active based cooling options were not economically viable (it is crucial to ensure optimization for the specific liquid (water) based active cooling technique followed by “smart regulation” in order to provide a more reasonable LCOE). However, with the proper optimization of active cooling techniques, it is more than reasonable to expect an additional LCOE reduction as it could significantly reduce the operating cost. The environmental analysis (LCA) showed that out of all the herein evaluated cooling techniques, the air based cooling techniques are the most harmful to the environment which is primarily due to more intense global warming and environmental acidification effect. Other environmental impacts are approximately of the same magnitude for the specific analysed active cooling options.