Solar Water Heaters

There are many different types of solar hot water heaters available in South Africa. They generally share two basic features, namely a collector (where the sun light heats up the water) and a storage tank (where the water is kept hot). But beyond these two common features, solar hot water heaters can vary significantly in design.

Solar Water Heaters - the basic idea

Solar water heaters are designed to use energy from the sun to heat water for your home. But for a solar water heater to work, you need sunshine. The various solar water heater manufacturers claim that, depending on climate and water use, a properly designed, installed, and maintained solar water heater can meet from half to nearly all of a home's hot water demand.

So, solar water heaters are perfect for the sunny climates of South Africa. I therefore find it ironic that solar water heaters are not being installed more widely in homes throughout South Africa.

Passive and Active Solar Water Heaters

Passive solar water heating systems rely on convection to pass the water through the solar collectors. These passive solar water heaters operate without pumps and controls. This makes passive solar water heaters more reliable, more durable, easier to maintain, longer lasting, and less expensive to operate than active solar water heater systems.

Active solar water heater systems have pumps, which moves the water or heat-transfer fluids from the collectors to the storage tanks. The pumps require controls, so that the circulation of fluids in the solar water heater can be properly regulated.

Both active and passive solar water-heating systems often require conventional water heaters as backups. This ensures that your house will have hot water available, even on rainy days or at night.

Solar water pre-heaters

Solar water heater systems are also often installed to function as pre-heaters for the conventional water heating units. This configuration supplies pre-heated water from the solar water heater to the inlet of the conventional water heating system.

So, the good old geyser doesn't have to use as much energy in the form of electricity or gas, to heat the water to the desired temperature.

Direct and Indirect Solar Water Heaters

A direct solar water heating system circulates the actual water that gets delivered to the house through the solar energy collectors. But this makes direct solar water heating systems inappropriate in climates where temperatures below freezing regularly occur.

Very low temperatures can cause the water to freeze in the solar energy collector pipes. And we all know what freezing water does! It expands. And the expanding ice will surely burst the pipes in the solar energy collectors.

But this does not mean that homeowners in Sutherland cannot make use of solar water heaters. An indirect direct solar water heating system should not experience any problems with freezing, because the fluid in the collectors is usually a form of antifreeze. The water is kept in an insulated storage tank, and instead of circulating the water through the solar energy collectors, this un-freeze-able heat transfer liquid is circulated through the solar energy collectors, and the heat is then indirectly transferred to the water, by circulating the water closely past the hot heat transfer fluids.

Choosing a Solar Water Heater

If you are considering purchasing a solar water heating system for your South African home, you may want to compare products from different manufacturers. And as with any appliance you purchase, do a bit of research of your own, instead of relying solely on the stuff salespeople tell you!

The South African Bureau of Standards (SABS) does tests on solar hot water systems too. So, you can trust a solar water heater, which bears the SABS mark of approval, to do what it says it does. But an SABS mark does not indicate how efficiently the solar water heater will perform for your home. Simply having an SABS label does not imply that the solar water heater has a superior performance.

The solar water heater sales person will most probably provide you with efficiency ratings of some kind, especially when they hear that you are comparing their product to other solar water heating systems. But just choosing the solar water heater with the best ratings is not good enough, either.

You have to consider if the solar water heating system incorporates proper design, sizing and durability for your specific needs. Someone living on the south coast of South Africa may for instance be quite happy with a particular solar water heater, but the owner of a home on the Highveld would need to know that the solar water heater will be able to withstand some hail.

Ask for references of clients in your area. And go and visit the actual properties where they are installed. You don't want to be speaking to folks who just recently got their solar water heaters installed. Tell the owner that you are considering a similar product, and ask them for their honest opinion.

Good installation and maintenance are also critical to ensure that the solar water heating system will function efficiently, and keep up the system performance.

Solar Water Heater Prices

The purchase prices and installation fees for solar water heaters are usually higher than for conventional hot water geysers, but the operating costs are much lower (sun light is still free, remember).

The one common factor in choosing any water heating system is the cost of the energy source. The sun is free. But remember, your solar water heater might have to fall back on conventional energy sources, if sunlight is not available. So, the energy costs may change dramatically in a short space of time, and especially in winter months.

Solar Water Heating Systems In South Africa

Solar water heaters just seem to make sense to me, living in sunny South Africa. The savings in energy costs should easily justify the higher initial cost.