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Sustainable Water Heating Solutions

More and more people are looking to solar power and solar water heating systems in order to embrace a sustainable lifestyle. Before you make any impulse decisions, it’s important to gain a clearer understanding of a few terms and products that may cause some confusion in the world of eco-friendly energy.

It’s no secret that geysers take up a large portion of the electricity bill each month.  With a solar water heater you reduce this cost substantially while simultaneously lessening your impact on the environment .

There are two eco-efficient means of heating water domestically or industrially.  The first is the solar water heating system and the second is the heat pump system. For clarity’s sake, in this post we’ll outline these two along with a few pros and cons.


This system uses radiation from the sun in order to capture the heat and transfer it to the water. Collectors are installed on rooftops and are directly exposed to the suns rays.

There are two collectors on the market:

1)     Flat plate collectors

These consist of a glass-topped insulated box of heat-absorbent black metal sheets attached to copper pipes.

2)     Evacuated tube collectors:

ETC’s are composed of a series of evacuated glass tubes. A vacuum inside each tube minimises the amount of heat loss, which is further retained by a thermal absorbent coating the inner lining of the tube. Built to withstand all climates, the evacuated tube collector will provide you with close to no maintenance costs for years to come.

The difference between the two collectors is minimal but evacuated tube collectors are more effective across the seasons, while when exposed to direct sunlight, the flat-plate collectors produce more heat.  Because of the external weather-dependent nature of solar water heating systems, electricity is still required to heat the water when sufficient solar heat has not been generated during the day. Solar water geysers in South Africa ideally have their collectors facing north for maximum exposure.

For best results the solar collectors are sized according to the volume of demand in the home and if effectively used this system could save approximately 75% on your water-heating bill. One must realize that this will be a different percentage saving on your TOTAL electricity bill, dependent on what portion of your electricity bill is dedicated to water heating.

There are various solar water heating configurations available that depend upon your solar hot water requirements:


This solar heating system can be mounted on rooftops and is comprised of a solar collector and solar geyser in one unit. There is no need for pumps because of the natural circulation process involved in the heating of the water and the displacement of the cold water that is commonly referred to as a Thermosiphon system.


The retrofit system reinvents your current geyser in order to accommodate for solar heating, achieved through evacuated tube collectors or flat plate collectors and a pump conversion kit.


This start-from-scratch solution allows one to install the geyser in a separate location to the collector, within reason, due to its sophisticated pump system. In other words, the geyser can be installed inside the roof away from the collector.


Heat pumps offer a radically different solution to sustainable solar water heating solutions.

The heat pump uses a small amount of electricity to power a pump and compressor and absorbs heat from the surrounding air which produces a consistent level of heated water..

Heat pumps use considerably less electricity than any other water heating applications.  The electrical input power to energy-dependent heat output generally has a power ratio of approximately 1:4; i.e. 1kW of electricity produces 4kW of heating energy.

So which option is best for you? It really does depend on your circumstances. The saving from a heat pump will most likely cover its cost faster than that of a solar water system, but should your collectors see large amounts of sun all year round, then a solar hot water system might be for you.

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