A Techno-Economic Analysis of Solar-Powered Air-Conditioning Systems with Thermal Energy Storage for Cost Reduction in Tropical Regions

Abstract

The rapid growth in cooling demand across tropical regions poses major economic and environmental challenges, exacerbated by rising electricity tariffs, unreliable power supply, and increasing ambient temperatures. This study presents a techno-economic assessment of a photovoltaic–thermal energy storage–variable refrigerant flow (PV–TES–VRF) air-conditioning system for a medium-scale office building in Nigeria. Building energy simulations indicate an annual cooling demand of 43,800 kWh, with peak loads occurring during the hot–dry season. A 32 kWp rooftop photovoltaic system generates approximately 150 kWh/day, directly meeting about 35–40% of annual cooling electricity demand. The integration of thermal energy storage (TES) provides up to 6 h of cooling autonomy, enabling 20–25% of evening cooling loads to be shifted away from the grid and reducing overall grid dependence by approximately 40%. Economic analysis over a 20-year project lifetime yields a levelized cost of cooling (LCOC) of ₦11/kWh, representing about a 40% reduction compared with conventional grid-powered air-conditioning. The system achieves a simple payback period of 6.5 years under current Nigerian electricity tariffs. Sensitivity analysis identifies electricity tariff escalation, photovoltaic capital cost, and TES capacity as key drivers of economic viability. The system also avoids approximately 2.7 t CO₂ annually. The results demonstrate that PV–TES–VRF systems are technically feasible and economically attractive for building cooling in tropical developing economies.