Efficient Power Conversion Using a PV-PCM-TE System based on a Long Time Delay Phase Change with Concentrating Heat

Based on the characteristics of phase change concentrated heat, this paper proposes a photovoltaic/phase change/thermoelectric (PV-PCM-TE) self-supply system with sidewall integrated TE. In the system, an intelligent control circuit for phase change time is designed to intelligently switch the TE working mode using real-time temperature tracking. Therefore, the phase change time of the phase change material (PCM) is delayed with enhanced heat absorption and storage capacity, resulting in greater suppression of the PV temperature rise. Based on the constant temperature difference during the delayed phase change, more electrical power output can be obtained with integrated multistage thermoelectric generators (TEG) in the sidewall of the PCM container. With the supplementary TEG energy injected into the PV battery, a complete self-powered design is constructed, leading to improved system energy efficiency. Experimental results show that compared with the PV-PCM-TEG system, the PCM phase change time of the proposed system is extended by 15 min, where the peak PV temperature after suppression is only 68.5 °C, which is 8 °C lower than that of the conventional PV-TEG-PCM system. The conversion efficiency of the entire system reached 30.26%, an improvement of 43.15%. The proposed self-powered PV-PCM-TE power conversion system with a long-time delay and high efficiency can operate during both day and night, providing a green scheme for intelligent low-power electrical systems.