Heating up water accounts for a good chunk of a home's energy use. It's a near-constant need -- we use hot water for showers, laundry, washing dishes -- and it adds up. Solar is an excellent clean energy source: Its fuel, sunlight, is limitless, free and emits nothing when converted into energy. The problem with solar, as most of us know, is its efficiency. Solar photovoltaic technology, or PV, is less efficient at converting its fuel into electricity than, say, a wind turbine. But when you're talking about heating water (as opposed to powering light bulbs or stereos), the sunlight doesn't need to become electricity. It needs to become heat. And turning sunlight into heat is no problem.
Basically, a solar water heater does one thing: It uses sunlight to warm water. What happens when we leave a glass of iced water outside in the winter sun? After a while, it's not iced anymore. It becomes warm.
Two things every solar water heater contains are a solar collector and a storage tank. A solar collector is basically a glazed, insulated box with a dark-colored interior and, usually, a bunch of tubes or passageways for water flow. (Glazing is a coat of material, typically glass that aids in heat retention.) The solar collector turns the sun's radiation into heat. A storage tank is exactly what it sounds like. It holds the water. The water tank is separate from the solar collector. Cold water moves through the tubes of a solar collector, and natural convection pumps the resulting hot water into a storage tank. From the storage tank, the water travels into the home's water pipes.
The benefits of solar water heating are numerous and considerable. First, you're going to save money on your electric bill.
Most likely, your water-heating electricity use will be cut by at least half. How much you actually save depends on the climate where you live. If you're in the North India where during winters, there is fog and lower sun shine, your savings will be lower than if you live in an extremely sunny place like Rajasthan, Gujarat, Maharashtra and Karnataka, because there's less fuel available for your system. People in Goa, Karnataka, Maharashtra, and hill states like Himachal Pradesh, Uttrakhand use warm water throughout the year, while Rajasthan, U.P. Haryana, Delhi and Panjab do not use hot water during summers. But still, most of the manufacturers claim 70% saving in electricity, when you use Solar Water Heater.
In most of India, there is an acute Power shortage. So, if there is no Power, there is no hot water. Cost of alternate fuels like LPG, Kerosene and diesel is going up. Solar Energy is free and in abundance. Properties like Hotels, Guest Houses, Restaurants, Commercial Kitchen, Hospitals, Hostels, and Factories etc which use hot water almost the whole off the year can save a substantial amount of money by installing Solar Water Heaters.
The Govt. Of India gives 30% subsidy on domestic and commercial Solar Water Heaters. This reduces the Capital cost of the system substantially.
Many State Govt’s give Capital Subsidy and/or Subsidy in the Electricity Bills. And then there's the corresponding reduction in pollution. A 50 percent reduction in traditional (emitting) energy use means a 50 percent reduction in CO2 emissions. So installing a solar water heater would reduce your hot-water carbon footprint by half. At the same time, you're conserving nonrenewable fuels for applications for which there are currently no easily available renewable energy sources.
Because of the benefits of solar water heating, adding a unit to your home will also increase its value. So you could end up getting back whatever money you put into a solar heating system when you sell your house.
Solar radiation falling on the collector passes through the glass and is absorbed by the absorber consisting of fin, raisers and headers. A special selective coating on the absorber prevents escape of heat to the environment. Water contained in the raiser and headers absorb the heat from the fins and raisers and becomes less dense than the water contained in the storage tank. It rises to the top of the hot water tank, simultaneously the cold water in the tank descends to the bottom header of the collector and gets heated in the absorber ; and the cycle is repeated. After such number of cycles the entire water in storage tank becomes hot.
Forced Circulation Type : In this type of solar water heater, water is pumped from the collectors to the tank. This type of system has a greater control on temperature output and is ideal for commercial and industrial establishments where hot water requirements are high.
Thermo Siphon Systems work on two principles viz :
The water from the solar tank travels into the collectors and is heated with the sun rays and returns back to the solar tank. This is called an Open Loop System. A collector without heat exchanger/close loop needs frequent de-scaling / cleaning, which results in damage of the copper tubes/absorber.
Models Available :
The water in the heat exchanger travels into the collectors and is heated with the sun rays and returns back to the heat exchanger. This hot water in the heat exchanger in turn heats up the water in the solar tank. This is called a 'close loop system' . This 'close loop' technology is to ensure uninterrupted working of the solar water heating system and also to safe-guard the solar flat plate collectors from scaling due to hard water, thus enhancing the life and performance of the collectors. (say upto 15 to 20 years).
Models Available :
In contrast to thermo siphon systems, an electrical pump can be used to move water through the solar cycle of a system by forced circulation. Collector and storage tank can then be installed independently, and no height difference between tank and collector is necessary.
Forced-circulation systems can be used for room heating as well as domestic water heating. In this case, collectors and storage tanks must be much larger than with simple domestic water heating systems, where a collector surface of about 4 mxm is sufficient for most households. Larger systems have also been realized successfully with two or more storage tanks.
Hot Water Storage tank is made of MS with glass enamel coating, double jacket heat exchanger and can withstand pressure upto 8 Bar.
Arinna 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 of solar radiation 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 heater scan 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.
|OUTER TUBE DIAMETER||58MM|
|INNER TUBE DIAMETER||48 MM|
|GLASS THICKNESS||1.6 MM|
|THERMAL EXPANSION||3.3X10 − 6 K|
|MATERIL||BOROSILICATE GLASS 3.3|
|ABSORPTIVE COATING||GRADED SS - C/CU|
|METHOD OF DEPOSITION||DC REACTIVE|
|SPUTTERINGABSORPTION||>92% (AM 1.5)|
|VACCUM||P<5X10 - 3Pa|
|HEAT LOSS||<0.8W/ (M20C)|
|PRESSURE ENDURE ABILITY||1MPa|