Towards next generation zero carbon heating plants integrated with solar thermal/photovoltaic system and thermal storage

The integration of renewable energy and the high-efficiency utilization of low-grade heat sources are defining characteristics of next-generation solar district heating (SDH) systems. Traditional SDH systems provide heating through a single photothermal and auxiliary heat sources such as gas boilers, which is an important reason why zero-carbon heating cannot be achieved. To achieve zero-carbon heating and study the impact of land rents on the economy of the systems, the conventional model, heat pump-coupled model, and PV-integrated model were established using the GenOpt-TRNSYS dynamic simulation and optimization platform, followed by a hybrid optimization algorithm-driven economic-technical analysis of all three models. Results demonstrated that, due to the water-to-water heat pump, the required scale of the collector field and pit was reduced by 22.3 % and 37.6 % respectively compared to the conventional model, but the heat pump-coupled model failed to achieve zero-carbon heating. In contrast, the PV-integrated model achieved zero-carbon heating through a “self-consumption with excess electricity fed into the grid” pattern, while simultaneously having the best economic and technical performance with a levelized cost of heat (LCoH) of 0.21231 ¥/kWh and a heat collection efficiency of 54.87 %. Scaling variations in equipment such as collector fields and photovoltaic arrays affect land occupation. Accordingly, a break-even analysis of land rents revealed that the PV-integrated model became economically favorable when land rents remained below 5.331¥/m2 yearly, whereas the heat pump-coupled model dominated under higher land rents. These findings provide critical theoretical guidance for system design and configuration optimization in next-generation SDH deployments.