Sun’s Radiant energy for heating water for residential purposes

Research shows that the water heating accounts for about 25 % of the energy used in an average household and is responsible for almost 23 % of the total greenhouse gas emissions from home energy use. Therefore Sun’s radiant energy if used to heat water can prove to be a great way to reduce our Carbon footprint. It can prove to be an ideal and efficient solution for most homeowners.

Solar hot water generation technology is proven and reliable technology.  In maximum of solar hot water systems, solar panels or solar collectors are used to absorb radiant energy from the sun. The solar collector is normally mounted on the roof, or in an area receiving direct sunlight. These collectors contain a fluid (a heat transfer fluid) which is heated by the sun as it passes through the collectors. This fluid is either pumped (active system) or driven by natural convection (passive system) through it. The heated fluid then heats the water in the storage tank. This heated water then flows into an insulated storage tank for later use. For getting an uninterrupted hot water supply even in the cloudy days, the storage tank is generally fitted with a normal water heater as well, which makes use of mains electricity or gas to heat the water.

There are three main types of solar collectors for collecting radiant energy from the Sun to be used for water heating for domestic applications:

• Flat-plate collectors
• Evacuated tube collectors
• Concentrating collector

Flat Plate Collectors for trapping Sun’s radiant energy:

The Flat-plate collectors are most commonly used for domestic space heating and water heating systems. It is basically an insulated metal box having glass or plastic/Polymer cover called the glazing and a dark absorber plate on the bottom.

Absorber plate absorbs the solar radiation and transfers the heat to a fluid that circulates in tubes through the collector. Flat plate collectors are either air-based collector or liquid base collectors. Air base collectors circulate air, whereas liquid-based collectors circulate fluid.

Evacuated tube collectors for trapping Sun’s radiant energy:

These collectors are more efficient than Flat plate collectors. These collectors consist of transparent outer glass tubes which allow sun’s radiant energy to pass through them. Inside each tube, one more tube is there, which is enclosed in a strong absorbing material that absorbs the sun’s radiant energy, generating heat. Water runs through this inner tube and is heated. A vacuum is maintained in between the outer tube and the water pipe which helps in eliminating any convective heat loss. Evacuated Tube Collectors are very efficient and show very good results but the problem with these collectors is that they are very costly in comparison to Flat plate collectors.

Concentrating collectors for trapping Sun’s radiant energy:

Concentrating collectors require direct Sun beam for solar water heating and in some cases electricity. In these collectors reflective surfaces are used to focus sunlight onto a small area. Working of concentrator collector is similar to the concept of burning the paper using a magnifying glass. As these collectors show their best performance while pointed directly at the sun, these systems make use of tracking mechanisms to move the collectors. Concentrating collectors are ideal for the climates having high percentage of direct sun’s radiant energy and few clouds, therefore are perfect for hot arid locations.

By using Sun’s radiant energy for generating hot water, you not only reduce your electricity expenses but also prove to others that you are serious for creating a better, greener environment. You can put forward a great example to your children and neighbors that you care enough for them by supporting eco-friendly alternatives for energy consumption.