Performance analysis of a medium concentrated photovoltaic system thermally regulated by phase change material: Phase change material selection and comparative analysis for different climates

Thermal management of photovoltaic systems is important since their electrical output decreases with the increase in temperature. Thermal regulation of a photovoltaic system using a phase change material is an effective technique, but a careful selection of PCM in terms of its thermophysical properties is essential for its better performance. In this work, performance analysis of a novel medium concentrated photovoltaic system employing two mono-facial polycrystalline cells is carried out. The system is thermally regulated with a phase change material. An experimentally validated finite element-based coupled optical, thermal, and electrical model is used to analyze the system's performance. The impact of the thermophysical properties of a PCM such as melting temperature, thermal conductivity, and heat of fusion on the thermal regulation of the system is studied using artificial neural networking methods. The optimum thermophysical properties of the PCM are determined using parametric analysis for the ambient temperatures ranging between 25 and 50 degrees C and a concentration ratio of 20x. Moreover, the performance of the system is analyzed using the optimum PCM for the semi-arid weather conditions of Lahore, Pakistan and the optimum PCM for oceanic weather conditions of Waterford, Ireland. It is found that the melting temperature, thermal conductivity, and heat of fusion of the PCM have a linearly indirect relationship with the temperature of the photovoltaic system while the ambient temperature has a linearly direct relationship with the photovoltaic system's temperature. The melting temperature of a PCM should be 10-15 degrees C higher than the ambient temperatures up to the ambient temperature of 40 degrees C. The melting temperature of a PCM was found to be 5 - 10 degrees C higher than the ambient temperatures for ambient temperatures greater than 40 degrees C. The required thermal conductivity of a PCM increases with the increase in ambient temperature ranging from 10 to 12 Wm(-1)K(-1) for the ambient temperature of 25 degrees C while 18-20 Wm(-1)K(-1) for the ambient temperature of 50 degrees C. The suitable heat of fusion is found in the range of 210-220 kJkg(-1). It is found that the optimum PCM for Lahore has melting temperature, thermal conductivity, and heat of fusion of 53-56 degrees C, 19 Wm(-1)K(-1) and 220 kJkg(-1) respectively. The optimum PCM for Waterford has melting temperature, thermal conductivity, and heat of fusion of 35-37 degrees C, 11 Wm(-1)K(-1) and 220kJkg(-1) respectively. The maximum temperature of concentrated photovoltaic cell for Lahore, Pakistan remains below 83 degrees C, while for Waterford, Ireland, it is below 59 degrees C for all the months in a year. From April to August, the output power is higher for Waterford with an average difference of 12%, while from September to March, Lahore has the higher power output with an average difference of 47%. The maximum power obtained for Lahore is 0.185kWh/day/m(2), while for Ireland it is 0.213kWh/day/m(2). A maximum deviation of 6% is found for electrical output and less than 3% for thermal output between simulated and experimental results during validation. [GRAPHICS] .