Solar Water Heater

We are blessed with Solar Energy in abundance at no cost. The solar radiation incident on the surface of the earth can be conveniently utilized for the benefit of human society. One of the most popular devices that harness the solar energy is "Redsun" solar hot water system (SWHS).

A solar water heater consists of a collector to collect solar energy and an insulated storage tank to store hot water. The solar energy incident on the absorber panel coated with selective coating transfers the heat to the riser pipes underneath the abosorber panel. The water passing through the risers get heated up and is delivered to the storage tank. The re-circulation of the same water through absorber panel in the collector raises the temperature to 80 C (Maximum) in a good sunny day. The total system with solar collector, storage tank and pipelines is called solar hot water system.

This type of systems are called Thermosyphon systems which are simple and relatively inexpensive. They are suitable for domestic and small institutional systems, provided the water is treated and potable in quality.

The Solar Water Heating systems are economical, pollution free and easy for operation in warm countries like India.

Based on the collector system, solar water heater can be of two types.

Flat Plate Collectors (FPC) based Solar Water Heaters:

The solar radiation is abosrbed by Flat Plate Collectors which consist of an insulated outer metallic box covered on the top with toughened glass sheet. Inside there are blackened metallic absorber (selectively coated) copper sheets with built in channels or risers tubes to carry water. The absorber absorbs the solar radiation and transfers the heat to the flowing water.

Evacuated Tube Collectors (ETC) based Solar Water Heaters:

Evacuated Tube Collector is made of double layer borosilicate glass tubes evacuated for providing insulation. The outer wall of the inner tube is coated with selective absorbing material. This helps absorption and transfers the heat to the water which flows through the inner tube.

Solar Water Heating is now a mature technology. Wide spread utilization of solar water heaters can reduce a significant portion of the conventional energy being used for heating water in homes, factories and other commercial and institutional establishments. Internationally the market for solar water heaters has expanded significantly during the last decade.