Analysis and optimization of the performance of a solar PV/T system integrated with seasonal latent heat storage for decarbonized heating and hot water supply

Incorporation of long-term heat storage in solar heating systems is deemed to be a way to tackle the seasonal mismatch between abundant solar energy in summer and strong heating demand in winter, e.g., in western China. To make up the adaptability of existing implementation of sensible heat storage, here we propose a new type of solar photovoltaic/thermal (PV/T) system integrated with seasonal latent heat storage (SLHS), using a highly-supercooled phase change material (PCM), at an energy-denser and more flexible manner. Starting from the configuration of a demonstration setup built in Hangzhou, China, the thermal performance of this system was studied numerically using TRNSYS. The efficacy of the system, equipped with a 12 m2 PV panel and a PCM-based SLHS unit of 15.6 GJ capacity, was confirmed for being able to supply hot water with daily average of 229 MJ and to maintain the room temperature at ∼20 °C for a 20 m2 heating area during the three-month heating season. Comparative simulations were also conducted for Lhasa, China, which is a representative targeted area. Not surprisingly, running this system in Lhasa can lower the global warming potential by nearly 30 %. With increasing the PV panel size the system can become self-sustained for off-grid users. After optimization of the PV panel size and SLHS unit capacity, the annual average coefficient of performance of the system can be improved by 160 % and the levelized cost of electricity can be reduced to only 0.68 CNY/kWh, showing great potential for practical applications toward decarbonized heating.