## Identifying a Good Solar Water Heater for your House

A Solar Water Heater is a device which provides hot water for any purpose using Sun’s thermal energy for heating the water. It is generally installed at the terrace or where sunlight is available. The water gets heated during day time and is stored in an insulated storage tank for use when required including mornings.

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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 flow automatically on thermosyphon principle to the storage tank. Hot water is then stored in the tank which can be used for various applications.

A good solar water heater should have sufficient collector area. For example, on a sunny winter day in India, a 1 sq. m. of collector area can heat around 50 litres of water to a temperature of 30-600C. Typical flat plate collectors those are available have an area of around 2 sq. m and are thus capable of heating 100 litres of water per day. Further, the collectors should use good materials and the absorbers should carry a good quality coating.

#### Selection of Solar Water Heater:

Before you purchase and install a solar water heating system, please make sure the following:

• Work out the economics of a solar water-heating system
• Evaluate your site’s solar resource, i.e. for many how many days Sun is available and in which direction and where you can install.
• Determine the correct system size
• Gather information on local codes, regulations and subsidies, tax exemption etc., available.
• Get comparative offers from more than one manufacturers and compare their specifications vis-à-vis cost and also their reputation, brand and actual user’s feedback about their after sales support and service.

#### Two Types of Solar Water Heaters are Available:

01. Based on flat plate collectors

02. Based on evacuated tube collector. Flat plate collector (FPC) based systems are of a metallic type and have the 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 the heat exchanger. They can also work with and without a pump. Systems without pump are known as thermosyphon systems and those with the pump are known as forced circulation systems.

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