Techno-economic and environmental accounting analyses of an innovative power-to-heat concept based on solar PV systems and a geothermal heat pump

This paper emphasizes the conceptualization and techno-economic-environmental analysis of a novel power-to-heat system based on the excess energy from solar photovoltaic (PV) plants and open-loop geothermal heat pumps (GHPs). This integrated energy system is engineered to supply simultaneously the electric load in a residential community and the heat demand in a primary school. The solar PV plant was optimized in a way to maximize the project net present value (NPV). Environmental accounting was as well introduced by estimating the total environmental penalty cost saving (TEPCS) for various carbon prices. Several scenarios were investigated, and corresponding optimum designs were determined. For annual electric and heat demand of 207.46 MWh ele and 13.67 MWh th in the residential community and the primary school, respectively, the optimum PV capacity to be installed is 26 kW p when no inflation of the grid electricity cost is considered. For this optimum PV capacity, the NPV is about 19.41 k$. The annual savings and discounted payback period for this case are calculated as 4.88 k$/year and 14.45 years, respectively. Including carbon prices enhanced the economic attractiveness of the concept. For a carbon cost of 40 $/tCO 2, the recommended PV capacity is 36.4 kW p giving rise to a TCS of 33.8 k$.