A Steady State Thermal Model For Photovoltaic/Thermal (PV/T) System Under Various Conditions
R. K. Koech, H. O Ondieki, J. K. Tonui, S. K Rotich
Key words:- Solar radiation, PV panel, PV/T collector, thermal model, electrical efficiency, heat exchanger
Abstract:- The increasing environmental concerns and the escalating conventional energy supply costs are creating a resurgence of interest in renewable energy resources. Hybrid Photovoltaic/Thermal (PV/T) solar technology is a relatively new solar conversion technology which convert the incident solar radiation into usable electrical and thermal energy simultaneously. The basis of this technology is the negative temperature coefficient of the electrical conversion efficiency of crystalline PV cells that leads to reduction in performance of installed PV panels at high irradiance levels. In addition, the commercially available PV modules have relatively low efficiencies of not more than 20% meaning that 80% or more of the incoming solar radiation is wasted and converted as heat, raising the operating temperature of the module. A low temperature fluid, usually water or air, is circulated through the heat exchanger attached to PV back to extract the excess heat from the panel hence cooling it in the process. The heat extracted can be harnessed and used for low temperature applications like space heating and ventilation in buildings or drying applications in agricultural and industrial sectors. In this study, a steady state thermal model of a PV/T air solar collector was developed, validated from experimental data and then used to study the effects of various parameters on the performance of the system. The results indicate that increasing the air mass flow rate when the design parameters are optimum will result into a significant increase in the overall performance of the system.
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