Energy Balance of Solar Water Heater

This work introduces a methodology for energy balance of solar water heaters (SWH). It describes the Israeli system for determination of the size of SWH, and calculations of the amount of energy gained by the SWH every month. It analyzes the central forced circulation system for the upper 9 floors of a residential building in Tel Aviv. The balance is for the demand scenario as determined using national statistics (unique to Israel). Electrical backup is 12% of the energy supplied by solar collectors. The balance shows that the energy consumption of hot water actually used is 57% of the total energy, and energy losses are 30%. 13% of the energy is not used as in summer SWH supplies more hot water than required. This work may be useful for a techno-economic evaluation of water heating options and calculations of optimal solutions. It also contains a large volume of useful data and information and can serve as a solar water heating manual or basic material for solar energy study.