Microgrid operation strategy for a photovoltaic-thermoelectric system integrated with microencapsulated phase change materials

To address dual challenge of low photovoltaic conversion efficiency due to waste heat and mismatch in thermal requirements within photovoltaic-thermoelectric generator (PV-TEG) systems, this study proposed a novel system integrating microencapsulated phase change materials (MPCMs), namely the PV-MPCM-TEG system. The innovation lay in utilizing MPCMs of varying melting temperatures to achieve more uniform thermal management and enhance overall power generation efficiency. Compared with conventional PV-TEG systems, the proposed system reduces PV cell operating temperature by 13.6 °C in summer and extends TEG power generation duration by approximately 4 h at night, improved 3.2% in overall system efficiency. Additionally, the system reduces building cooling load by 34.2% in summer and heating load by 7.8% in winter through its thermal buffering effect on building envelope. Furthermore, a grid-connected microgrid was constructed with this system as power supply. Corresponding operation and dispatch strategies were proposed under two different residential electricity price policies. Under a stepped pricing policy, a strategy of ‘discover and use now, store the surplus electricity’ reduced microgrid operating costs from 31,693.7 CNY to 30,962.8 CNY in July (saving 2.3%) and from 14,669.5 CNY to 14,460.5 CNY in February (saving 1.4%). Under a time-of-use pricing policy, a ‘self-generation for self-consumption and peak shaving for valley filling’ strategy reduced costs from 849.3 CNY to 672.4 CNY on a typical summer day (saving 20.8%), and from 1143.1 CNY to 990.6 CNY on a typical winter day (saving 13.3%). The results demonstrated effectiveness of the proposed system and strategies in significantly improving economic performance.