Solar water heater uses in hotels in Pacific Island Countries: Techno-economic-environmental analysis for a typical hotel in Fiji

The hospitality sector in Pacific Island Countries (PICs) is highly energy intensive and remains strongly dependent on imported fossil fuels for hot water production, leading to elevated operational costs and greenhouse gas emissions. This study presents a techno-economic-environmental assessment of a glazed flat-plate solar water heating (SWH) system for a representative 3-star hotel in Fiji. Using RETScreen Expert, multiple system configurations were simulated by varying the storage-to-collector area ratio to identify an optimal design. The selected system achieves a solar fraction of 45.5 % and delivers annual energy savings of approximately 9,996 kWh. Over a 20-year project lifetime, the system reduces cumulative greenhouse gas emissions by about 158 tonnes of CO₂. Financial analysis indicates strong economic viability, with a simple payback period of 7.7 years, an equity payback period of 4.7 years, and a net present value of FJD 15,151, achieved without subsidies. Model outputs were independently validated using the System Advisor Model (SAM), demonstrating close agreement between the two tools. The findings confirm that SWH systems represent a technically feasible, economically attractive, and environmentally sustainable solution for reducing fossil fuel dependence in Fiji’s hotel sector. The proposed system directly supports Sustainable Development Goals (SDGs) 7 and 13 and contributes to SDGs 8, 9, and 11 through improved energy efficiency, emissions reduction, and sustainable tourism infrastructure.