Solar water heating systems feasibility for domestic requests in Tunisia: Thermal potential and economic analysis

Abstract

The main goal of the present work is to study the energetic and the economic potential of the deployment of Domestic Solar Water Heating systems (DSWHs) instead of using electric/gas/town gas water heaters. A case study related to Tunisian scenario was performed according to a typical Tunisian households composed of 4–5 persons. In this scenario we evaluated the performance and the life cycle perspective of the two most popular DSWHs over the recent years (i.e. DSWH with flat-plate solar collector, FPC, and DSWHs with evacuated-tube solar collector, ETC). The dynamic behavior of DSWHs according to Tunisian data weather was achieved by means of TRNSYS simulation. The Results showed that the FPC and ETC provide about 8118 and 12032kWh/year of thermal energy. The economic potential of DSWHs in saving electricity and reducing carbon dioxide emissions was also investigated. Results showed that the annual savings in electrical energy relatively to the FPC and ETC are about 1316 and 1459kWh/year, with a payback period of around 8 and 10years, respectively. Based on gas/town gas water heater, the FPC and ETC save about 306m3 and 410m3 of gas/town gas with a payback period about 6 and 7.5years, respectively. We found that the life cycle savings by installing the solar system instead of buying electricity to satisfy hot water needs are about $3969 (FPC) and $4400 (ETC). We establish also that the use of the DSWHs instead of installing gas/town gas water heaters save about $1518 (FPC) and $2035 (ETC). From an environmental point of view the annual GHG emission per house is reduced by 27800tCO2.