Annual analysis of the photovoltaic direct-expansion heat pump assisted by double condensing equipment for secondary power generation

Thermoelectric generation (TEG) converts heat directly into electricity based on temperature difference. Many studies on combining TEG with photovoltaics to convert waste heat into electricity to increase overall power generation have been conducted. However, through previous research, if TEG was installed between the cooling and PV, it will hinder PV heat dissipation and cause electricity deterioration, which could not be compensated by TEG output. To ensure the PV cooling and meanwhile realize thermoelectric conversion, a photovoltaic direct-expansion double-condensing heat pump system based on TEG assisted by micro-channel heat pipes and water-cooling condenser is proposed. Experiments & mathematical model are carried out & verified. The regional weather conditions at different latitudes and altitudes are adopted to predict the system performance on a year basis. From the results, the electrical efficiency is improved due to the additional TEG power output. With a higher ambient temperature in Hongkong, the heating capacity is higher, but the compressor consumption also increases. With better irradiation and a lower ambient temperature, Garze has brilliant electrical performance, the COPPVT & NEER are the highest at 9.9 monthly & 8.0 annually. Furthermore, the operating costs and CO(2)emissions of this system are just 1/4-1/3 and 1/3-1/2 of gas boiler, indicating significant potential for energy-savings & emission reduction.