Technical and economic assessment of a hybrid solar PV-grid geothermal system in arid climates

This study explored the implementation of a combined geothermal and solar energy system tailored for space conditioning in arid climates, with Kuwait serving as the principal case study. The proposed solution incorporates a water-source geothermal heat pump system coupled with a vertical borehole ground heat exchanger (VBGHE) supported by a hybrid photovoltaic system integrated with an electrical grid. The design is intended to serve a six-story residential building comprising two-bedroom apartments, where each unit is equipped with two geothermal heat pumps operating in conjunction with VBGHEs to maintain indoor temperatures of 22°C during winter and 26°C in summer. The performance of the system was assessed numerically by examining photovoltaic-grid hybrid configurations, both with and without battery storage components. To optimize both thermal energy use and cost-effectiveness, this study utilized TRNSYS 18 for detailed thermal simulations and hybrid optimization of multiple energy resources (HOMER) PRO for comprehensive techno-economic analysis. The analysis revealed significantly higher annual cooling demands than the heating requirements for apartment complexes. Among the evaluated configurations, the hybrid photovoltaic (PV)-grid system without energy storage emerged as the most viable solution, supplying 55.7% of the electrical load through solar PV and the remaining 44.3% from the grid. This configuration reduced the total annual energy costs by 80%, achieving a competitive levelized cost of energy (COE) of 0.077 USD·kWh −1 and a net present cost (NPC) of 22,280 USD, with a 4.1% return on investment (ROI) and a 12-year payback period. Furthermore, the hybrid system reduced CO 2 emissions by 2,100 kg·year −1 . Sensitivity analysis confirmed that the proposed system maintains a significantly COE than grid-supplied electricity across all scenarios, including the least favorable conditions. Beyond these economic advantages, the system provides substantial environmental benefits through measurable reductions in CO 2 emissions.