Solar Water Heating System

Solar water heating system is a device that uses solar energy to heat water for domestic, commercial, and industrial needs. Heating of water is the most common application of solar energy in the world. A typical solar water heating system can save up to 1500 units of electricity every year, for every 100 litres per day of solar water heating capacity.

  • Parts of the Solar Water Heating System

    • A solar water heating system consists of a flat plate solar collector, a storage tank kept at a height behind the collector, and connecting pipes.
    • The collector usually comprises copper tubes welded to copper sheets (both coated with a highly absorbing black coating) with a toughened glass sheet on top and insulating material at the back. The entire assembly is placed in a flat box.
    • In certain models, evacuated glass tubes are used instead of copper; a separate cover sheet and insulating box are not required in this case.
  • Working of a solar water heater

    • The system is generally installed on the roof or open ground, with the collector facing the sun and connected to a continuous water supply.
    • Water flows through the tubes, absorbs solar heat and becomes hot.
    • The heated water is stored in a tank for further use.
    • The water stored in the tank remains hot overnight as the storage tank is insulated and heat losses are small.
  • Uses of solar water heater

    • SWHs can be used at homes for producing hot water that can be used for bathing, cleaning, and washing. Solar water heaters (SWHs) of 100-300 litres capacity are suited for domestic application. Larger systems can also be used for a variety of industrial applications. Hot water at 60-80oC could be obtained through use of solar water heaters.
    • Fuel Savings: A 100 litres capacity SWH can replace an electric geyser for residential use and saves 1500 units of electricity annually.
    • Saves cost on power generation - The use of 1000 SWHs of 100 litres capacity each can contribute to a peak load saving of 1 MW.
    • Environmental benefits - A SWH of 100 litres capacity can prevent emission of 1.5 tonnes of carbon-dioxide per year.
    • Pay back period - SWHs have a life span of 15-20 years. The pay back period is about 3-4 years when electricity is replaced, 4-5 years when furnace oil is replaced and 6-7 years when coal is replaced.