Type of systems available in market

Basically two types of solar water heaters are available in the market. One with Flat plate collectors (FPC) and the other with Evacuated tube collectors (ETC).

FPC based systems are of metallic type and have longer life as compared to ETC based system where tubes are made of glass which are of fragile in nature. ETC based systems are, therefore, cheaper than FPC based system.

Quality of Systems

Government has laid down minimum technical requirements for ensuring quality of solar water Heaters being installed in field which are mandatory for all suppliers. These requirements are placed at Annexure-I. The requirements are such that they can be easily monitored by users themselves also. Finding not adhering to the requirements, users can complaint to Haryana Renewable Energy Development Agency (HAREDA) for taking action against the suppliers.

Selection of System

For a house with one bathroom and 3 to 4 members, 100 litre per day capacity system should be sufficient. For more numbers of bathrooms, the capacity will increase accordingly due to pipe losses & more number of family members. Generally the capacity is decided based on hot water required in mornings for bathing. If the usage is in evening & at other times also, the capacity is decided accordingly.

ETC based systems may perform better in colder regions and avoid freezing problem during sub-zero temperature. FPC based systems also perform good in colder regions if they are used with anti-freeze solution and heat exchanger but then their cost increases.

At places where water is hard and have larger chlorine content, heat exchanger must be installed with FPC based system as it will avoid scale deposition in copper tubes of solar collectors which can block the flow of water as well reduce its thermal performance. ETC based systems do not face such problem but may reduce performance due to scale formation inside the tubes which can be easily cleaned by dismantling the tubes one in a year or so.

How to get system installed?

System can be installed from Ministry of New & Renewable Energy (MNRE), Govt. of India’s accredited Channel Partners / approved manufacturers whose lists with phone no. are given on website of Ministry : mnre.gov.in.

Avoid getting electricity back up installed in storage tank of solar system, if you already have an electric geyser. It may be installed in upper portion of storage tank only if you don’t have electric geyser. Also if the geyser is of say less then 10 lpd capacity or it is an instant geyser it would be better if the outlet line of solar system is connected with inlet of electric geyser by setting thermostat at 40^{º .} Your geyser will start only when you get water below 40^º  from solar system due to clouds/rains etc and will switch off when temperature goes above say 42 or so. This will save lot of electricity & heat water according to your requirement. However, if you have storage geyser of high capacity, better to have a separate tap for solar system and use your electric geyser when you don’t get hot water from solar system on cloudy/rainy days.