Techno-economic feasibility of solar water heating system: Overview and meta-analysis

Solar water heating system (SWHS) has been increasingly adopted for domestic hot water production (accounts for 20% of global household energy use), spacing heating, and thermal facade. Although several reviews on SWHS technological development are available, a literature review on the techno-economic viability of SWHS is lacking, which is critical for practical application of this technology. This paper aims to provide an overview of the existing techno-economic analyses of SWHS. The technology level, supplementary energy type, natural conditions and policy support are identified as key factors influencing the payback period of SWHS. Meta-analyses are conducted to analyse the effects of these key factors on the payback period. A regression model is developed, considering several study characteristics such as the methodology, continent and study year. The results show 9 negative effects (evacuated tube collector, number/area of collectors, use diesel as supplementary fuel, radiation, specific region, residential sector, numerical estimation and study conducted in Europe) and 7 positive effects (tank water temperature required, hot water consumption pattern, computer modelling/simulation, experiment, case study, study conducted in Asia and South America) on the payback period of SWHS. This study provides useful information to improve the techno-economic performance of SWHS for wider applications.