Maximizing the energy output of a photovoltaic-thermal solar collector incorporating phase change materials

Photovoltaic-thermal collector can simultaneously generate both electricity and heat, making full use of the solar energy. It is worth to increase the electrical output by reducing the operating temperature. An effective method of cooling the cell temperature is incorporating phase change materials into the collector. In order to maximize the energy output and improve the performance of the collector, we perform comparative analyses on a hybrid photovoltaic-thermal solar collector incorporating phase change materials with different melting point. Solar cell temperature, electrical power, electrical efficiency, outlet temperature of water, thermal power output of the collector by varying melting point and thickness of phase change material layer are evaluated using one dimensional energy balance method. The corresponding graphical representations are described to explain the way of maximizing the electrical and thermal energy output of this system. And the numerical results have provided guidance for further experiment. In this theoretical work, it is found that phase change material layer with lower melting point has better electrical properties of the collector, while the heat stored in phase change material layer is more difficult to utilize. The results show that the photovoltaic-thermal solar collector gets a maximum of overall energy output by incorporating 3.4cm-thick phase change material layer with 40 °C melting point. By contrast of the electrical power of 30 °C melting point case and no phase change material case, the biggest value of difference is 16.12 W at 12:00. It means that the electrical power of the collector has increased around 13.6% by incorporating phase change material layer with 30 °C melting point.