What is Solar Water Heater?

A Solar Water Heater is a device which provides hot water for bathing, washing, cleaning, etc. using solar energy. It is generally installed at the terrace or where sunlight is available and heats water during day time which is stored in an insulated storage tank for use when required including mornings.

Application Typical Requirement of Hot
Water at 60OC.
Household bathing using buckets 10-20 liters per person per bath
Household bathing using shower
with a mixing tap
20-30 liters for 10-15 minute
Shaving, while a tap runs 7-10 liters
Household bathing in bathtub (one
50-75 liters
Wash basin with a mixing tap (hand
wash, brushing of teeth, etc.)
3-5 liters per person per day.
Kitchen washing 2-3 liters per person per day.
Dishwasher 40-50 liters per wash cycle
Clothes washing machine 40-50 liters per cycle


How does it work?

A Solar Water Heater comprises of an array of solar collectors to collect solar energy and an insulated tank to store hot water. Both are connected to each other. During the day time, water in solar collectors gets heated which is either pumped or flown automatically on thermosyphon principle to the storage tank. Hot water then stored in the tank can be used for various applications

What are different types of Solar Water Heaters?

Two types of Solar Water Heaters are available; one based on flat plate collectors and the other based on evacuated tube collectors. Flat plate collector (FPC) based systems are of metallic type and have longer life as compared to Evacuated tube collector (ETC) based system because ETCs are made of glass which are of fragile in nature. Both these systems are available with and without heat exchanger. They can also work with and without pump. Systems without pump are known as thermosyphon systems and those with pump are known as forced circulation systems.

Is there any subsidy available from Government?

No. The subsidy scheme has been discontinued w.e.f 12.08.2014 onwards.

Why should I go for a Solar Water Heater? What do I save from it?

A 100 litre per day capacity system suitable for 3-4 people can save up to 1500 units of electricity in a year depending on t h e a m ou n t o f hot water used. It can also save around 140 litres of diesel in an establishment using oil fired boiler besides reducing greenhouse gas emissions in the atmosphere. Higher capacity systems will save higher
amount of electricity/fuel oil besides reducing higher amount of GHG emissions.
Electricity is expensive and is not available due to power cuts in many areas when required for heating water. Solar Water Heater, since it stores hot water in an insulated tank, provides water all the time when required. Fuel oil is also expensive and creates pollution. Storing the fuel oil for long term use in commercial establishments is another problem.
The table below gives approximate likely electricity and money savings for a typical 100 liters per day system located in different parts of the country.

What happens on cloudy/rainy day? Do I still get hot water?

On cloudy days also, if it is for a day or two, you still get warm water as water gets heated due to diffused radiation available in the atmosphere. The system, however, is either connected to an electric geyser in the house or an electrical back-up is provided in the storage tank of the system which is switched on when water is not sufficiently hot. So, you get hot water all the time even on rainy days.