Solar water heaters require only a one-time investment, after which there are no running costs, writes Deepti Adlakha Solar solutions: It is important for people to recognise the underlying potential of solar energy. The recent fuel crisis has created an urgent need to examine and opt for alternate sources of energy. Buildings could be one of the places to begin this rethinking and given the tropical location of this country, solar energy offers itself as a clean and viable option. A typical solar water heating (SWH) system comprises a stainless steel storage tank, aluminium solar collectors, copper risers and an absorber sheet. The selection of a system to match needs is dependant on the usage and water consumption per day. A 100 litres per day (LPD) capacity system with one panel is suitable for approximately 4-6 people and results in a saving of 120 units per month. Installation To ensure efficient functioning of the system and for optimum results, the system must be installed on the roof top in a shadow free area facing south. The bottom of solar tank should be at a minimum of five feet from the roof top. Solar water heaters do not have any capacity constraint, which offers the advantage of modifying and adapting it to suit one's needs. TATA BP Solar domestic use water heating systems are available in models of 100 LPD, 200 LPD and 300 LPD and have been designed to work efficiently even on cloudy days and also with hard water with hardness up to 600 ppm. Multiple modules can be added on to further increase the capacity of the system. Benefits and advantages Solar water heaters require only a one-time investment after which no running costs are incurred. Mr. Raghunathan, Managing Director of Solkar Solar Industry Limited says, "The payback period could be computed to less than three years. If you were to buy a solar heater for say Rs.24,000, you could for a payback period of three years effectively save up to Rs 6,000- Rs 8,000 per annum of your electricity bill, assuming that hot water is used for 10 months in a year.' For domestic applications, the SWH system is the most cost-effective uses of solar energy compared to conventional geysers in the long run. Also, by directly reducing greenhouse gas emissions (carbon dioxide, CO2) released into the atmosphere, it contributes towards a healthier green environment. Photovoltaic panels An array of photovoltaic panels can be used to generate electricity from solar energy which can then substitute various domestic applications and appliances. Solar modules are designed to absorb and produce electricity from the sun and store it in a battery for usage at night or during power outages. The solar powered