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Solar Water Heater
  • Solar Water Heater
  • Solar Tubes
Thermosyphon Tubular Solar Water Heater, Solar Geyser, Stainless steel
  • SFA-SS series
Low-pressurized thermosiphon solar water heater. The most popular and economical natural circulation system.

The design of this type uses the Thermosyphon principle.


The SFA evacuated tube solar water heating panel is the simplest vacuum tube system available. The stainless steel cylinder at the top of the panel is the well-insulated hot water cylinder - it is double skinned and has two inches of polyurethane foam between the two skins. The stainless steel construction means that it will not corrode, and its simplicity requires no ancilliary components. The vacuum tubes are double-skinned, with a vacuuum between the two layers of glass. The water in the cylinder is able to enter the central section of each vacuum tube, where it is heated by the sun. The tubes themselves are 93% efficient - so they are able to heat water even in low sunshine or when ambient air temperatures are low. The warmer, less dense water rises into the storage cylinder, displacing cooler water which descends into the tube for heating. 


The design of this type uses the principle of Thermosyphon. This type of system does not use heatpipes; instead the water is filled into the tubes, which in turn heat the header tank (which can vary between 85 and 220litres) by convection.It has obvious advantages:with a tank itself and the fittings are very low-cost. However, it is less functional, too large to appear roof-integrated, cannot accept pressure system kits.This type is commonly employed in hot countries such as Turkey, Greece, Mediterranean, Africa etc.


Solar water heater Feature: 

1)Beautiful in design and very convenient for family use 
2) Reliable and efficient with twin-glass solar tubes 
3) Easy plug-in installation 
4) Outer tank material: stainless steel plate or powder coated color steel sheet 
5) Inner tank material: 0.5mm thick SUS304 food grade stainless steel plate 
6) Frame material: color steel 
7) Superior heat preservation ensured by 50 - 65mm polyurethane foam insulation layer. Enjoy the hot water in cold evening 
8) No corrosion: It can prevent corrosion lead from chorine ion, sea water, salt water or buck water 
9) No leakage: Apply for special anti-corrosin layer 
10)Sanitary water: The qualities showed above make it possible that water quality is pure and no twice pollution 
11)Desinging the immersin heater hole in advance for the clouldy,snowy,rainy days 


The Principle of Thermosyphon

The Principle of Thermosyphon solar water heater

A. Tube coupled to a flow-through reservoir B. Tube coupled to a closed tank C. Open thermosyphon


Because of the larger proportion of hot water than cold water, cold water flows downward and hot water goes upward. The water will be heated continuousl between water tank and vacuum tube. In other wards, hot water always floats on cold water.
The hot-water flows to the water tank from the vacuum tubes. Because of the proportion, cold water flows to vacuum tubes from the water tank. 
The cold water is heated in vacuum tubes.After it becomes hot water, it flows to water tank again. The water circulates constantly between water tank and vacuum tubes; the cold water in water tank will be hotter and hotter. 
Finally, all cold water will be heated to be hot water. This is the heating course of cold water. 


Solar water heaters working principle


Tube & tank interaction during peak solar radiation conditions.


Scope of Application: 

SFA series Solar water heaters popular in Asia,Africa,torrid zone and warm area.


Notice : 

1) The angle of the frame can be changed in production as the local latitude condition of the customers. We can design the suitable angle for the customers 
2) We offer the spare accerssories and tubes for your order for free 
3) We can offer the different material of water tank,frame anf tubes according to your request 
4) We offer the fittings of this system,like immersion heater,water supplier,magnesium and so on.You can buy according to your requirement 

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SFA series Solar water heaters Specifications:

Item No. Specification Tank's 
and solar 
Effective Qty (set)

Diameter of
water tank

Qty. of
of solar
of solar
area M2
20GP 40HQ
SFA47155818 470mm 5pcs Ø 58mm 1.8M 130L  175L 1.89 54 130
SFA47185818 470mm 18pcs Ø 58mm 1.8M 155L 210L 2.27 46 110
SFA47205818 470mm 20pcs Ø 58mm 1.8M 170L 230L 2.52 42 100
SFA47245818 470mm 24pcs Ø 58mm 1.8M 210L 280L 3.03 36 85
SFA47305818 470mm 30pcs Ø 58mm 1.8M 260L 350L 3.79 28 68

1. Model explanation: Take SFA47155818 for example, “SFA” is Sunflower’s solar water heater SF-A series products, “47” means the external diameter of water tank is 470mm, “15” means the tube quantity is 15 pcs, “5818” means the vacuum tube is 1.8 meter  ф58mm.
2. Above solar water tank net capacity is ±2%.

SFA series Solar water heaters Package and Size:


Solar water heater size


Model Size(mm)
SFA42154715-SS 1170 1060 1307 1346
SFA42184715-SS 1380 1270 1307 1346
SFA42204715-SS 1520 1410 1307 1346
SFA42244715-SS 1800 1690 1307 1346
SFA42304715-SS 2220 2110 1307 1346
SFA47155818-SS 1348 1228 1594 1655
SFA47185818-SS 1591 1471 1594 1655
SFA47205818-SS 1753 1633 1594 1655
SFA47245818-SS 2077 1957 1594 1655
SFA47305818-SS 2563 2443 1594 1655

Package: Solar Water tank, Solar Standing Frames, Solar tubes are separately packed in one carton. Cartons can be loaded into container directly. 

Optional Accessories for SFA series Solar Water Heaters:

Item Picture Name Describe
1 Water Supplier Used to fill the water into big water tank automatically.
2 Controller Display panel with Connection box
Temperature sensor and water level sensor for water tank
electromagnetic valve for filling water
220V 50HZ/110V 60HZ
If you choose this, you do not need water supplier
3 Magnesium Rod It can help the equipment of the solar heater system such as the water tank, the evacuated tube etc. preventing water incrustation, melting silt and preventing erosion by lower cost.
4 Electric Heater Use to heat water in rainly days
5 Ball Valve As a switch in system
6 Constant Temperature Mixing Valve Function: It is used to mix cold water and hot water of system, to avoid the potential danger when the outlet hot water temperature is too high. You could set the temperature by yourself, bring you more comfortable bath in warm water, and energy saving.
Note: Voltage range 110 V ~ 240 V, frequency 50 Hz or 60 Hz, plug can be selected for the specifications of your country.