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 & institutional establishments. Internationally the market for solar water heaters has expanded significantly during the last decade. It is estimated that over 107 million m2 of collector area has so far been installed worldwide for heating water. In the country, the collector area so far installed for water heating is over 1million m2. Ministry has plans to add another 2 million m2 in next two years.
Solar water heaters (SWHs) of 100-500 liters capacity are suited for domestic application.
Larger systems can be used in restaurants, canteens, guest houses, hotels, hospitals etc.
Features
High quality tubes made from borosilicate glass
No clogging/choking
Long lasting
Better performance in winter and cloudy days
Inner glass tube is coated with the world best magnetron sputtering Hi-Tech, layers of AL – N with AL base
Vacuum jacket insulation
Heats water to a very high temperature
Makes hot water available even on partially cloudy days
High quality PUF insulation for maintaining high temperature of water inside the tank
Compact and light weight water heater
Easy to install, operate and maintain
Works efficiently with hard water
SS 304 tank for hot water storage tank
Special coated MS stand
Safe and environment friendly
Systems Available – 100, 125, 160, 215, 250, 300, 500 LPD
Details
Evacuated tubes are the absorber of the solar water heater. They absorb solar energy converting it into heat for use in water heating. Evacuated tubes have already been used for years in Germany, Canada,india, China and the UK. There are several types of evacuated tubes in use in the solar industry. Life long solar collectors use the most common “twin-glass tube”. This type of tube is chosen for its reliability, performance and low manufacturing cost.
Each evacuated tube consists of two glass tubes made from extremely strong borosilicate glass. The outer tube is transparent allowing light rays to pass through with minimal reflection. The inner tube is coated with a special selective coating (Al-N/Al) which features excellent solar radiation absorption and minimal reflection properties. The top of the two tubes are fused together and the air contained in the space between the two layers of glass is pumped out while exposing the tube to high temperatures. This “evacuation” of the gasses forms a vacuum, which is an important factor in the performance of the evacuated tubes.
Why a vacuum? As you would know if you have used a glass lined thermos flask, a vacuum is an excellent insulator. This is important because once the evacuated tube absorbs the radiation from the sun and converts it to heat; we don’t want to lose it!! The vacuum helps to achieve this. The insulation properties are so good that while the inside of the tube may be 150oC / 304oF, the outer tube is cold to touch. This means that evacuated tube water heaters can perform well even in cold weather when flat plate collectors perform poorly due to heat loss (during high Delta-T conditions).
In order to maintain the vacuum between the two glass layers, a barium getter is used During manufacture of the evacuated tube this getter is exposed to high temperatures which cause the bottom of the evacuated tube to be coated with a pure layer of barium. This barium layer actively absorbs any CO, CO2, N2, O2, H2O and H2 out-gassed from the evacuated tube during storage and operation, thus helping to maintaining the vacuum. The barium layer also provides a clear visual indicator of the vacuum status. The silver coloured barium layer will turn white if the vacuum is ever lost. This makes it easy to determine whether or not a tube is in good condition.
Evacuated tubes are aligned in parallel; the angle of mounting depends upon the latitude of your location. In a North South orientation the tubes can passively track heat from the sun all day. In an East West orientation they can track the sun all year round.
The efficiency of evacuated water heater is dependent upon a number of factors, one important one being the level of evacuated radiation (insolation) in your region. To learn more about insolation.
Specifications
| Length | 1800 mm |
| Outer Dia. | 58 mm |
| Inner Dia. | 47 mm |
| Weight | 2 kg. |
| Material | BOROSILICATE GLASS 1.6mm |
| Selective Coating | CU\SS\AL N |
| Absorptance | 95% |
| Emissivity | 5% |
| Vacuum | 5X10-3 PA |
| Thermal Expansion | 3.3X10-6 DEG C’ |
| Heat Loss | 0.8W/M2 DEG C’ |