Solar Water Heater - ETC

Solar Water Heating System can provide hot water using solar thermal energy for various applications in industrial, commercial and domestic sectors. The collector is kept normally on the roof top preferably facing south.

Working Principal

A solar thermal collector is a solar collector designed to collect heat by absorbing sunlight. The term is applied to solar hot water panels, but may also be used to denote more complex installations such as solar parabolic, solar trough and solar towers or simpler installations such as solar air heat. The more complex collectors are generally used in solar power plants where solar heat is used to generate electricity by heating water to produce steam which drives a turbine connected to an electrical generator. The simpler collectors are typically used for supplemental space heating in residential and commercial buildings. A collector is a device for converting the energy in solar radiation into a more usable or storable form. The energy in sunlight is in the form of electromagnetic radiation from the infrared (long) to the ultraviolet (short) wavelengths. The solar energy striking the Earth's surface depends on weather conditions, as well as location and orientation of the surface, but overall, it averages about 1,000 watts per square meter under clear skies with the surface directly perpendicular to the sun's rays.

Types of solar collectors for heat

Solar collectors fall into two general categories: non-concentrating and concentrating. In the non-concentrating type, the collector area (i.e. the area that intercepts the solar radiation) is the same as the absorber area (i.e., the area absorbing the radiation). In these types the whole solar panel absorbs the light.

Flat plate and evacuated tube solar collectors are used to collect heat for space heating, domestic hot water or cooling with an absorption chiller.

Evacuated tube collectors

Evacuated Tube Collector based Solar Water Heater

Most (if not all) vacuum tube collectors use heat pipes for their core instead of passing liquid directly through them. Evacuated heat pipe tubes (EHPTs) are composed of multiple evacuated glass tubes each containing an absorber plate fused to a heat pipe. The heat from the hot end of the heat pipes is transferred to the transfer fluid (water or an antifreeze mix—typically propylene glycol) of a domestic hot water or hydronic space heating system in a heat exchanger called a ―manifold‖. The manifold is wrapped in insulation and covered by a sheet metal or plastic case to protect it from the elements.

The vacuum that surrounds the outside of the tube greatly reduces convection and conduction heat loss to the outside, therefore achieving greater efficiency than flat-plate collectors, especially in colder conditions. This advantage is largely lost in warmer climates, except in those cases where very hot water is desirable, for example commercial process water. The high temperatures that can occur may require special system design to avoid or mitigate overheating conditions.

Some evacuated tubes (glass-metal) are made with one layer of glass that fuses to the heat pipe at the upper end and encloses the heat pipe and absorber in the vacuum. Others (glass-glass) are made with a double layer of glass fused together at one or both ends with a vacuum between the layers (like a vacuum bottle or flask) with the absorber and heat pipe contained at normal atmospheric pressure. Glass-glass tubes have a highly reliable vacuum seal but the two layers of glass reduce the light that reaches the absorber and there is some possibility that moisture will enter the non-evacuated area of the tube and cause absorber corrosion. Glass-metal tubes allow more light to reach the absorber and protect the absorber and heat pipe (contained in the vacuum) from corrosion even if they are made from dissimilar materials (see galvanic corrosion).

The gaps between the tubes may allow for snow to fall through the collector, minimizing the loss of production in some snowy conditions, though the lack of radiated heat from the tubes can also prevent effective shedding of accumulated snow.


NON PRESSURISED MODEL - Domestic 100 LPD, 150 LPD, 200 LPD, 250 LPD, 300 LPD, 400 LPD ( Compaq), 500 LPD Manifold
PRESSURISED MODEL - Domestic 200 LPD, 250 LPD, 300 LPD
NON PRESSURISED & Pressurized MODEL - INDUSTRIAL 750 LPD, 1000 LPD, 1250 LPD, 1500 LPD, 2000LPD, 2500 LPD, 3000 LPD


  • Hot Dip Galvanized Thick Tank (Thick Tank Gives More Strength)
  • Mg- Anode is used for to avoid corrosion of Tanks
  • PUF Insulation ( Insulation injected With Processor for a particular temperature & Pressure )
  • Marine Inside Coating
  • GI Powder Coated side cover
  • G.I. Sheet Stand
  • Powder Coated GI Base Stand upto 400 LPD – Above 400 LPD Powder Coated MS Angle Base Stand
  • World's latest innovated technologies.
  • High temperature.
  • Less scale due to tube big diameter
  • Electric Back up ( Optional)
  • Almost Nil Maintenance
  • Payback Within 3 Yrs


Heat Pipe

The heat pipe consists of a highly conducting fluid enclosed inside the pure copper tube of diameter 8mm sealed on both the ends.

The non-toxic liquid inside the Copper heat pipe has a boiling point of 25OC. So when the heat pipe is heated above 25 degreee C, the liquid vaporizes. The vapor rapidly rises to the top of the heat pipe transferring the heat to the cold water inside the tank. As heat is lost at the condenser top, the vapour condenses to form a liquid and returns to the bottom of the heat pipe to repeat the process. Each heat pipe is tested to 250oC. For this reason the Copper heat pipe is relatively soft. Because of high temperature, the glass tube is given a twelve-layer coating. Given the strict quality control and high Copper purity, the life expectancy of the heat pipe is even longer than that of the solar tube.

Greenlife Pressurized Model

Sunlight, incident on the Vacuum Tube, passes through the outer transparent glass tube and strikes the outer surface of the inner glass tube with selective coating (AIN/AI). This glass tube, which acts like a black body, absorbs the radiation and the heat pipe gets heated up in the process. The presence of vacuum between the two tubes prevents heat loss to the surroundings. The heated inner tube transfers this heat to the heat pipe which is directly in contact with water inside the storage tank. Hot water is lower in density and therefore has a tendency to rise up. Cool Water from the tank flaws down to replace the hot water, facilitating circulation by thermosyphon. And through this process, the entire water in the storage tank heats up and gets ready for use.

The storage tank is insulated with PUF, which minimizes the heat loss at night.