Energy and thermo-fluid-dynamics evaluations of photovoltaic panels cooled by water and air

• Published in: Solar energy Vol. 105; pp. 147 - 156
• Main Authors: Arcuri, Natale, Reda, Francesco, De Simone, Marilena
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.07.2014; Elsevier; Pergamon Press Inc
• Subjects: Applied sciences; Cooling; Cooling system; Direct energy conversion and energy accumulation; Efficiency; Electric currents; Electrical engineering. Electrical power engineering; Electrical power engineering; Energy; Energy analysis; Equipments, installations and applications; Exact sciences and technology; Natural energy; Photoelectric conversion; Photovoltaic cells; Photovoltaic conversion; Photovoltaic panel; Simulation; Solar cells. Photoelectrochemical cells; Solar energy; Temperature; Energy analysis; Efficiency; Photovoltaic panel; Cooling system; Water; Performance evaluation; Conversion rate; Numerical method; High temperature; Finite element method; Air temperature; Photovoltaic array; Open circuit; Fluid mechanics; Short circuit currents; Fluid dynamics; Photovoltaic system; Thermophotovoltaic device; Cooling by water; Open circuit voltage; Solar cell; Irradiation; Hot water production; Software; Typology
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2014.03.034

•Different cooling systems of PV panels are investigated.•Water and air as work fluids were studied and constructions aspects were analyzed.•The air speed field was verified comparing simulated results with measured profiles.•Cooling performances of simple air and water systems were evaluated.•For the best cooling solutions an energy analysis was carried out by TRNSYS. The main limit of photovoltaic (PV) systems is the low conversion efficiency of cells, which is strongly influenced by their operating temperature. As the temperature increases the short circuit current (Isc) increases moderately, while the open circuit voltage (Voc) decreases considerably. The cell temperature reduction is a useful methodology that could be used in order to improve the PV panels performance of both new and already installed as well. This solution is interesting especially for high irradiation level locations with high external air temperature range along the daytime, because the maximum producibility occurs when the irradiation is high and therefore, as a consequence, the cell temperature increases. Furthermore, the proposed solution could be integrated with many PV typologies, already installed as well. Thus, it represents an alternative to PVT (Thermal–Photovoltaic) systems, which need DHW consumers for supplying the heat produced, otherwise the performance of the system will decrease. Various solutions adopting respectively a cooling water system and an airflow lapping the back of the panels in an open circuit is investigated to individuate the best cooling solution. Finite element software that describes with extreme detail the thermal exchange between the PV cells, the external environment and the cooling system is used in order to assess the reached temperature of the cells with different cooling system configurations calculating for each considered cases the overall thermal losses coefficient. Regarding the air cooling system configuration, which results less invasive, a comparison between the simulated and the measured, by laboratory tests, air speed has been conducted. Hourly energy simulations for the best configurations using the software TRNSYS are carried out to evaluate the annual performances.