Solar geysers made simple…

 The South African solar geyser market has been flooded with an influx of foreign and local companies trying to gain market share in this ever – growing but still fledgling industry. Some are fly by nights, some are established organizations with plenty of experience. With so many options and such different information, the million dollar question remains. Which system should you purchase and why?

I think that there is a consensus amongst consumers that solar geysers do work and will play a major role in the future of green energy, green building design and the way in which we heat water on a daily basis. The key to deciding on the correct system lies in understanding how it all works.

Any solar water heating system is made up of two main components, the geyser and the solar collector. The solar collector is responsible for generating heat and the geyser’s function is to store that heat so that it can be used at the consumer’s convenience.

What is the difference between a direct geyser and an indirect geyser?

There are two different types of solar geysers, a direct geyser and an indirect geyser. A direct geyser means that the water that is circulating through the solar collector is the same water that will be used by the consumer, we call this the potable water. An indirect geyser means that the liquid that is circulated through the solar collector never comes into contact with the potable water that is used by the consumer, the geyser is heated indirectly through a transfer of heat by means of a heat exchanger inside the geyser. The main reason that we use an indirect geyser is to protect the solar collector from freezing. we are able to put an anti – freeze liquid inside the collector.

 Indirect solar geyser with heat exchanger

What is a thermo-siphon system?

Solar geysers work on the principle that heat rises and cold sinks. This is known as thermo – siphon, natural circulation of heat and cold. Based on this principle it is easy to understand that the most efficient way to plumb a solar geyser is to have the geyser above the collector, that way heat will be transferred naturally from the collector to the geyser.  It is common for the geyser and the collector both to be situated on top of the roof in this configuration.

Should you wish to have the geyser sitting inside your roof, you will usually need a pumped system. The geyser will sit below the collector. Heat will rise up the collector naturally and will have to be circulated down into the geyser by means of a circulation pump. This will be monitored by a solar controller to ensure greater efficiency.

Flat plate collectors vs Vacuum tubes

Flat plate collectors are the more traditional form of solar collectors, they use copper pipes to carry the heated liquid to the geyser, they usually have a backing of insulation to keep inside heat inside the collector and are dark in colour to attract as much of the suns radiation as possible.

Vacuum tubes are round which gives them a bigger surface area, they are able to store heat very efficiently due to the fact that no heat can escape the vacuum between the two layers of glass.

Both technologies have their place in their market. Both have features and benefits that can be argued for. At the end of the day provided that you have a system that is specked and installed correctly, they will work very similar to one another. Their efficiencies should be good and they should be able to withstand the elements over time.


In a typical hose hold, a geyser will make up 40% of the total electricity bill. With a solar geyser, we aim to save the consumer around 70% of that 40%, basically 30% of your total electricity bill. This translates to a payback period of around 2 – 3 years at the current electricity prices. What a great investment!

At Unlimited Solar we have the full range of solar geysers. We believe that they each have their place in the market. We have done all our research so that you, the consumer, can feel confident in the system we supply to you.

Visit one of our branches where we have the systems on display. This way you will be able to see exactly how the systems work, get to feel the hot water and learn more about the technology.


Solar Geyser Systems

Unlimited Solar is an alternative energy supply company. We are dedicated to bringing you the highest quality products at the right prices whilst always maintaining a high service level.

We have a wide variety of solutions on offer including Solar Geysers, Heat Pumps, Photovoltaic systems and Swimming Pool heating. We encourage you to visit one of our branches and experience our unique service offering which gives customers the opportunity to see our products in action and learn more about this exciting industry.

Due to our wide range of products and our large installer database we are able to tailor make a solution for each individuals needs.

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