Helping You To Become Energy-Smart

Buying a Solar Water Heater

It is strongly recommended that you only purchase from a SESSA accredited supplier or installer. Consult the SESSA Member Directory for a list of accredited installers in your area.The SESSA Ombudsman is also at hand to address problems or issues arising as a result of manufacturing problems, poor installation or bad service from a supplier or service provider.

You should be able to answer the following questions:

  • Is the supplier and or installer listed with SESSA?
  • Is the SWH system a SABS tested and passed system or SABS Mark system?
  • Are you prepared to have a tank on the roof?
  • What size of system do you require?
  • What is the efficiency of the system?
  • What are the likely daily kWh savings?
  • What does the system cost?
  • What is the payback period?

When going solar, the last thing you want to do is to under-size a system leading to situation that does not deliver according to one's expectations. The table below provides a guideline based on potable hot water consumption. A soft science approach is to start at the temperature that one washes or showers at being 40 ºC. A good 5-minute long, high pressure shower at 20 litres per minute amounts to 100 litres per person at 40 ºC . Two people will therefore use 200 litres. In order to get 200 litres of 40 ºC hot water, a solar water heater of 150 litres will provide this but it needs a Q performance of at least 17.5 to 20.5 at 20MJ /m2 per day.

 System & Household SizeDaily Requirement of Hot (40 ºC), Potable Water 
      Thrifty Usage Average Usage
People: human iconhuman icon   140 litres 200 litres
SWH System Size:150 litres ‘Q’ Factors Required: 17.5 20.5
People: human iconhuman iconhuman icon    210 litres 300 litres
SWH System Size:200 litres Q’ Factors Required: 25 30
People: human iconhuman iconhuman iconhuman icon    280 litres 400 litres
SWH System Size:200 or 300 litres ‘Q’ Factors Required: 34 40
People: human iconhuman iconhuman iconhuman iconhuman icon    350 litres 500 litres
SWH System Size:300 litres ‘Q’ Factors Required: 42 50
People: human iconhuman iconhuman iconhuman iconhuman iconhuman icon    420 litres 600 litres
SWH System Size:300 litres ‘Q’ Factors Required: 50 60

Check with your supplier both the size and the power output of the system at 20 MJ. Too small or not powerful enough and you will always be using the electrical back up, and will be disappointed by the electrical savings. This is one area where size does matter!


Solar Water Heaters range considerably in price and performance. The quality of systems do vary, but the first consumer check is to make sure that it has been tested and passed by the South African Bureau of Standards (SABS). All SWH should carry a minimum of a 5-year warranty against manufacturer defects. When a SWH is being sold it is extremely important to consider both the size (the volume of water) that is being heated, and the efficiency of the system. For example a 300L system that is only 50% efficient will give the same electrical savings as 150L system that is 100% efficient. The biggest disappointment that consumers face is lower than expected electrical savings and lower than expected reduced electricity bills. This is generally because they have bought a system that is too small, not having taken into account the amount of hot water that is actually being used by the home. The SESSA accredited supplier should be able to supply you with a system that meets your hot water requirements, and the information on this website provides you with impartial information to help avoid buying a system that is too small or not efficient. Consumers are advised to ask additional questions regarding retrofits (solar systems that are fitted to existing electrical tanks), and using a solar water heating system as a pre-feed system.

The SWH supplier and/or installer may be able to provide credit facilities for the purchase of the system. Credit facilities from private lenders tend to be very expensive. If buying on credit check the overall impact on the cost of the system, and the payback period after credit finance.

If you have a bond on your home some banks will extend the bond for the purchase of the SWH. Again check the arrangement fee and costs of borrowing and compare against the electrical savings and financial savings.

A number of SWH suppliers are now offering Solar Water Heating rental schemes. These can be advantageous if the electrical and related financial savings are greater than the cost of renting. It overcomes the capital costs required to go solar, and depending on the scheme can provide a purchase option at the end of the rental period. As more credit schemes become available SESSA will add information to facilitate purchases.

Electrical geysers can fail like any appliance. They do not actually burst (assuming they have been correctly installed), but start to leak. This occurs mainly as a result of corrosion over time, caused by a process of electrolysis, where the water molecules are accelerated very rapidly when the element is turned on, which in turn results in a very mild acidic solution being created through the chlorine in the water. This acid attacks exposed metal where sacrificial anodes are installed for that very purpose. When the sacrificial anode is exhausted, unless it is replaced, the mild acid solution will then attack the tank, rather like rust. In time corrosion results in a pin prick leak and as the geyser cannot be repaired, it needs to be replaced.

Most insurance policies cover the cost of a replacement electrical geyser. Some insurers are prepared to offer a solar system in replacement, but as solar water heaters are considerably more expensive, look for an additional contribution from the policyholder. Consumers that suffer a geyser insurance claim should request a 'solar ready' geyser, or a 'solar geyser' (with electrical back up) in replacement, which can be subsequently fitted with the solar collector, on which the energy incentive rebate may be claimed.

The insurers will also benefit from solar water heaters being installed, in that the amount of corrosion is likely to be far less, as far less electricity will be used, thereby limiting the amount of corrosion. The life expectancy of the tank will be increased significantly, and future claims will reduce. With climate change being a major concern for the insurance industry, any low hanging fruit for reducing carbon emissions is a necessity.