Experimental research of photovoltaic-valley power hybrid heating system with phase change material thermal storage

Abstract

The widespread integration of high-ratio distributed photovoltaic (PV) systems in buildings calls for flexible load management to align with municipal power peaks and PV variability. To address the timing and demand mismatches between PV generation and building energy needs, energy storage systems are used to manage PV excess, aid in grid peak shaving, and support building heating. This research develops a Photovoltaic-Valley power complementary phase change energy storage heating system, designed to consume photovoltaic and valley power for the decentralized heating of individual rooms, thus optimizing distributed energy utilization. A CPCM of magnesium chloride hexahydrate, EG, and calcium hydroxide, designed for indoor heating, was created with a phase change temperature around 117.9 °C and an enthalpy of 106.2 kJ/kg. An experimental platform was established to test the system and its control strategy, showing that the PV-powered phase change energy storage heater effectively keeps indoor temperatures above the thermal comfort minimum of 18 °C. As the PV guarantee rate increases, the system improves indoor temperature regulation and significantly reduces fluctuations. Operating costs are over 30% lower than those of traditional heating networks and natural gas systems, underscoring substantial energy savings and emission reductions. This research provides an integrated approach for optimizing building PV consumption, managing grid peaks, and regulating indoor temperatures with phase change energy storage heating systems.