Solar Water Heater System

 Solar water heaters use solar energy to heat water for a variety of uses, including home, businesses and industrial uses. Swimming pools heating, under-flooring heating, space heating or cooling are other possible uses of solar thermal energy.
Solar hot water systems are composed of solar collectors, which collects energy from the sun. The heat collected is moved, through a fluid system, from the collectors to a storage tank and from there to the point of usage. The system may use electricity for pumping the fluid, or heat convection, depending on the type. The system may include also thermostats and a controller device to control the operation based on temperature differentials and hot water demand. In most cases a solar water heater can provide up to 85% of domestic hot water.
Solar water heaters can be passive and active. Passive solar water heaters, also called thermo-siphon, do not required a circulating pump to move the fluid from the collectors to the tank. The tank is located above the collectors and the fluid circulates by heat convection. This type of solar thermal system is inexpensive, easier to install, and work well in warmer climates.
Active solar hot water systems use a pump to circulate the heat transfer fluid, or water, from the collectors to the storage tank. This type of system is usually more efficient than passive systems, but are also more expensive, and more difficult to install.
Solar water heaters require larger and well-insulated storage tank. It is possible, but not necessary, to keep the existent electric or gas water heater by interconnecting the system already in place to the solar water heater. The solar water heaters pre-heats the water for the conventional water heater reducing the energy required, gas or electricity, to heat the water.
Two types of solar collectors are used for most all applications: flat-plate and evacuated-tube collector. Flat-plate collectors are indicated to warmer climates. Evacuated tube collectors are suitable to colder climates, larger residential or commercial applications. Both types of solar collectors can be used for passive or active systems.

Two types of Solar Water Heater System

Evacuated tubes are regarded as the most efficient and cost effective solar water heating method of producing natural hot water. As the name suggests the tubes contain a vacuum which has been manufactured with a single, double or triple wall construction. The glass on the inner tube is coated on its outer surface with an absorbent coating, and on its inner surface with a reflective coating. The tubes are vacuums which have a copper heat pipe which runs through the middle of the tube.

The heat pipe carries the heat, which is generated by infra red radiation, up the tube to be collected. The heat pipe contains anti freeze which allows heat to be generated even in freezing temperatures. The heat from the copper pipe is transferred into the Header Pipe through which more antifreeze flows. This heated antifreeze is then pumped through the hot water tank where the water gets hotter and the antifreeze gets cooler. The antifreeze then returns to the solar heating module to be heated again. This flow is constant resulting in the water in the tank becoming hot.

Evacuated Tube Collector Specification

Specification (Units) 47 Diameter tube 58 Diameter tube
Material Borosilicate glass 3.3 Borosilicate glass 3.3
Selective Coating materials AL/SS/CU AL/SS/CU
tube length (mm) 1500 1800
outer tube diameter (mm) 47 58
glass thickness (mm) 1.6± 0.15 1.6± 0.15
absorption coefficient (pct) ≥0.93(am1.5) ≥0.93(am1.5)
emission coefficient (pct) ≤0.065(80±5) ≤0.065(80±5)
transmision coefficient (τ) (pct) ≥0.890(am1.5) ≥0.890(am1.5)
max strength (mpa) 0.8 0.8
vacuum pressure (pa ) ≤5.0×10-3 ≤5.0×10-3
weightof a single tube (kg) 1.3 kg 2.2 kg
thermalexpansion (degree) 3.3*10-6 / degree 3.3*10-6 / degree
insulation temperature (degree) 200 200
resist cold (degree) -35 -35
resist hailstone (mm) 25 25
start-up temperature (degree) <=25 <=25


  • Inner tank : SS 304/ SS 316
  • Outer tank : Powder Coated Aluminium/SS polish 0.45mm thickness
  • PU Thickness : 50mm
  • Colour : Black side caps and SS Polish Sheet or yellow powder coated aluminium sheet for outer covering with anti dust rings.
  • TIG Welded Out let of 1" inch on both sides of tank.
  • Inlet & Outlet of 3/4 inch.
  • Heater provision of 1 1/4th inch on hot water outlet side.


  • Material : MS, Channel of min 3mm Thickness
  • Colour : Black Powder coated anti collision Materials


  • Size of Tube :47 x 1500MM. / 58 x 1800MM
  • Coating :Triple Coated (SS-Al/Cu)
  • Colour of tube :Blue
  • Specification sheet for tube attached.


  • Tubes will be packed in a box of 15 pcs. / 10 pcs.
  • For tanks and stands Box will be of 5 ply with 160 GSM thick.

Solar flat-plate collectors [ FPC ] are suitable for warmer climates. Flat-plate collectors are affordable and easy to install. For a household size of 4 to 5 people, two flat-plate collectors should be enough to provide 80% of all hot water needs. The first step begins by determining the volume of hot water needed and whether there is area available for the installation. Solar collectors can be installed on the roof or on the ground.

Flat-plate solar collectors specification: Aluminum frame, galvanized steel plate, rock wool insulation, red copper pipes, fin and tube with brazed joints.

Flat-plate solar collectors Specification

Dimensions 80x39x3.75 in
Total area 23.4 sqft
Aperture size (m2) 21.2 sqft
Absorber size (m2) 21.5 sqft
Net Weight 81.6 lbs
Capacity 0.46 gal
Flow rate 21 gpm (0.35 gpm)
Pressure Loss 160mbar (water, propylene-glycol, 68 F)
Collector Connections 2 connectors at top - 3/4 NPT Connector Fittings
Absorber Type 12mm / Serpentine, laser-welded to aluminum absorber plate
Absorber Coating Highly selective on aluminum
Absorption / Emission 95% / 5%
Covering Low iron, clear, solar safety glass (ESG)
Transmission of Covering 88%
Cover Impact Resistance Passed optional impact resistance tests following EN12975-2
Insulation Mineral wool / 1.2"
Collector Frame Material Powder coated aluminum
Efficiency eta 0: 77.6% (relative to aperture area)
Heat Loss Coefficient - a1 (k1) 3.95 W/(m2K)
Heat Loss Coefficient - a2 (k2) 0.0165 W/(m2K)
Maximum Stagnation Temp. 375.8 F (191 C)
Maximum Operating Pressure 10 bar
Warranty 10 Years
Set up angle 20-90 degree
Heat loss 5.0w/C m2
Flow rate 1.35 GPM
Lifetime 10

Solar water heater based on FPC

Capacity From 125 litres to 3000 litres and more as per system size.
Material of Construction Stainless Steel 304 L , TIG welded (Argonwelded) with certified Stainless Steel ER308L filler wire.
Type Cylindrical - Horizontal Reinforced Tanks
Dimension & Thickness of Plate
Capacity Dia Thk Thk















Pressure Testing Hydro tested for leakage detection.
Insulation PUF Insulation with 40Kg. Density (40mm thick)
Glass wool Insulation with 48Kg. Density (100mm thick)
Rockwool Insulation with 100Kg. Density (100mm thick)
Insulation Covering 26 SWG Aluminium sheet
Sealing Covering completely sealed with Silicone sealant for water proofing of insulation.