Solar geysers – The different types

There are many different types of solar geysers to consider, however it doesn’t necessarily have to be an unpleasant experience. Below are the different available types with relevant information to assist you with all your water heating needs. Remember, if you still require assistance please give us a shout, we are always ready to assist the public in making the right choice to go green.

To give you some perspective on why need to consider a solar geyser, here are some interesting facts.

  • The geyser is usually responsible majority of your electricity bill
  • Solar geysers can effectively provide warm water for up to 15 years, if not longer
  • You are less dependent on the overall grid
  • The options you get with solar collector kits ensures there’s a package that fits your budget
  • You can make your money back on the investment within 2 years
  • You save thousands over the course of several years
  • The maintenance required for a solar geyser is almost non-existent, unless there are moving parts involved such as a pump
  • A solar geyser is just as capable of heating water up to 90 degrees
  • The installation is quick and very straightforward

Solar water collectors

What is a collector? A solar collector is the component that is placed in a position where the sun rays are used to heat the water. The cold water travels through the inlet and is heated, thereafter either gets pumped or rises into the geyser for storage and use.

Flat plate collector

A flat plate is perfect for our South African conditions. It does require direct sunlight, predominately North facing to heat the water and should be clear of all cast shadows from trees or buildings. Although not as efficient as the evacuated tube system, this is far effective enough for our hot conditions.

Evacuated Tube solar collector

Evacuated tube collectors are the most efficient collectors on the market. Originally it was designed for European conditions where sunlight is scarce and the temperatures are much colder. This collector system uses UV rays and not direct sunlight. With this, it also has heating rods that amplify the heating process to achieve higher temperatures than that of the flat plate collectors. Being that our conditions are extremely hot in South Africa, the use of evacuated tubes are recommended to be used in the following conditions to avoid over heating and wasting of water due to vacuum release:

  • East / West facing roof
  • Partially shaded placement of collector
  • Freezing conditions

Pumped solar geyser system (Retrofit)

A pumped system is used when the storage tank or electric geyser is used and is below the position of the collector. Water from the geyser is needed to be re-heated and is required to be pumped up into the collector and back down once heated into the geyser. Although more parts involved make this a higher maintenance option due to there being moving parts, it is also a cost effective route as well as less of an eyesore due to the tank not being visible on the roof.

Thermosiphon solar geyser systems

These solar geyser systems are the most common and most reliable systems as there are very little parts involved along with the main process being a natural one. Cold water is pushed into the solar water collector and is then heated by the sun. Because heat rises and cold sinks, all the hot water is automatically pushed t the top of the collector and into the geyser that is placed above the collector. When the water cools it pushes the cold water back down into the collector and re-heats. This process happens with no aid of any mechanical means.

Direct Thermosiphon solar geyser system

A direct thermosiphon solar geysers utilize a standard thermosiphon geyser that needs not be protected for cold conditions. Although still made to withstand weathering in the outdoors, it does not offer any extra insulation for water storage. Very good for coastal areas and areas that do not reach 0 degrees.

Indirect Thermosiphon solar geyser system

An indirect thermosiphon solar geysers system is designed for areas situated in extreme cold conditions. Being that the geyser is on the roof, it is exposed to the open air and ice deposits from the temperature drops. The indirect geyser has a jacketed layer around the cylinder that gets filled with glycol, an insulating liquid, that ensures the temperature of the water in the tank is kept from freezing or cooling too fast. These systems are best for inland areas where it drops down to 0 degrees or below in winter.

Closed coupled solar geyser systems

Closed coupled solar geysers are 1 piece systems. The tubes go directly into the tank utilizing sleeves to connect it. These are direct thermosiphon systems so are purely designed for areas that are not extremely cold in the winter time.

Low pressure solar geysers

Low pressure solar geysers are closed coupled systems that transfer the hot water using gravity. These systems are perfect for farm areas or areas where the temperature never really reaches below 15 degrees. Because the hot water is gravity fed, the cold water mixing usually makes it too cold to use, therefore only having a very light shower conditions.

Frequently asked questions:


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