Solar FAQ

How does solar water heating work? It is a simple process of using light from the sun to heat water. Every solar water heating system consists of a collector (also called a panel) and a storage tank (also called a geyser). Water is circulated from the geyser through the collector, getting hotter as it circulates.

Does solar water heating generate any electricity?

No, generating electricity from solar radiation is an entirely different technology. There is no electricity generated in solar water heating.


How much can a solar water heating system save me?

A conventional geyser is usually responsible for 30-40% of the average household’s electricity bill. You can eliminate 70-80% of this consumption by going solar.


What will a solar water heating system cost?

The upfront cost will be between R15,000 and R35,000, but you will receive an Eskom rebate of between R3,500 and R13,500 in cash 8 weeks after you install your system.


Why are Eskom offering a rebate on solar water heating systems?

Eskom have something called a demand side management programme, which exists to reduce electricity demand, and particularly peak time electricity demand, across the country. They have identified solar water heating as one of the most viable ways of reducing electricity usage, and are offering the rebate as an incentive for people to install systems.


How does one apply for the rebate?

We handle the rebate application process on behalf of our customers. You need to do supply us with a copy of your ID, a copy of your rates bill as proof of address, and a copy of your electricity bill / your pre-paid meter number. You also need to fill out page 1 of the rebate form and sign it. We do all the rest and submit the form.


How can I be sure that I will receive the rebate?

So far all of our clients have received their rebates. The rebate payment process is being administered by Deloittes, who have shown a high level of professionalism in their handling of the process.


How long will it take for my solar water heating system to pay for itself?

We estimate that the savings from installing a solar water heating will cancel out the capital investment within 3-5 years. This number is much lower than it used to be, partly because of the Eskom tariff hikes and partly because of the generous rebates currently on offer.


How do I decide what size system to install?

The number of people permanently living in your house will determine the size of the system that you require. When converting to solar water heating it is a good idea to increase the size of your geyser. A bigger geyser means that you will be able to store more solar heated water and use less electricity.


For 1-2 people in a house we suggest a 150 litre geyser, for 2-3 people we suggest a 200 litre geyser and for 4-6 people we suggest a 300 litre geyser.


Will I have hot water at night?

The system is designed to deliver hot water around the clock. Hot water is retained in a specially insulated geyser and can be kept hot overnight. The geyser also has a 2kW backup element, which can electrically boost the temperature of the water if required.


Will I have hot water in winter?

The solar energy that is absorbed by the system comes from the sun’s radiation, not from direct heat, so it doesn’t have to be hot outside for you to generate hot water. The geyser also has a 2kW backup element, which can electrically boost the temperature of the water if required.


Will I be able to use my old geyser?

It is usually a good idea to install a new solar geyser. However, if your geyser is less than 7 years old and is a Kwikot, it is possible to convert it for solar water heating purposes.


What is the advantage of using a solar geyser as opposed to converting my existing geyser?

A solar geyser has two main advantages. The first is that it has better insulation than an ordinary geyser and so keeps water hotter for longer. The second is that it has specific ports for circulating the water through the solar collector, so it isn’t necessary to fit conversion valves.


How hot does the water get with a solar water heating system?

Solar systems heat water to the same temperature as conventional geysers. In fact, sometimes solar systems produce hotter water than conventional geysers. That’s why we fit mixing valves to your hot water supply so that the water reaching your taps is never dangerously hot.


What is the life expectancy of our systems?

All of our systems are designed to last 20 years or more. We pay a lot of attention to the materials that make up the system, as well as the overall build quality of the units.


What is the Yes Solar guarantee period?

This varies from system to system. Solartherm geysers have a 10 year warranty, and most of our collectors have either a 5 or 10 year warranty. All of our workmanship is covered for 1 year.


Will I still have hot water on the days when the sun doesn’t shine?

The short answer is yes. Solar geysers are fitted with a 2kW electrical element which kicks in when there isn’t enough sunshine to get the water hot enough.


What is the difference between flat plate and evacuated tube systems?

The difference is in the type of collector used. Flat plate collectors are an older, simpler technology. Water (or heat exchange fluid) runs through copper pipes on a black surface, with a layer of glass covering them. The black surface helps to heat the water in the pipes. An evacuated tube system is a newer, more complicated technology. Water (or heat exchange fluid) runs through a manifold that is connected to a series of heat pipes.


Which is better – flat plate or evacuated tube systems?

At Yes Solar we offer both technologies. We believe that both perform well in South Africa, where we have really good sunshine. Evacuated tube systems are usually slightly more efficient than flat plate systems, especially in cold winter conditions. Evacuated tube systems are also less sensitive to collector pitch and orientation, as well as incoming water temperature.


More important than your choice of technology is making sure that your system is built to last and is backed up by a supplier who will still be around in 10 years time!


What is the difference between a thermosiphon system and a pumped system?

The word ‘thermosiphon’ describes a system where water is circulating from the geyser to the collector and back again purely by convection – cold water from the geyser drops to the bottom of the panel, rises through the panel as it gets hotter and then rises back up into the geyser. This only works if the geyser is above the panel!


When the geyser is not above the panel a pump is needed to force the water to circulate from the geyser through the panel and back again.


How is the pump powered?

We offer both mains powered AC pumps, as well as solar powered DC pumps. The solar powered pumps have a small photovoltaic panel that powers them.


Doesn’t the power required for the pump cancel out the electricity saved in the geyser?

No, the pump uses a really small amount of electricity (22W) compared to a geyser element (4000W). In fact, the pump uses less electricity than an ordinary light bulb!


Which way does the collector have to face?

Because we’re in the southern hemisphere, the collector should ideally face due north. However, anywhere between north-west and north-east is OK. The performance of evacuated tube systems is affected less by the direction they’re facing.


What pitch does the collector have to be at?

The ideal pitch in Cape Town is 43 degrees. However, anything between 25 and 75 degrees is fine. Being at 43 degrees means that the collector is optimized for winter when the sun is low. In summer the sun is almost directly overhead, but because there is so much sun it’s actually better that the collector isn’t getting it straight on.


What if the pitch of my roof is less than 25 degrees?

If the pitch of your roof is really too low we will raise the collector to the appropriate level using a custom built frame. We are also able to install collectors on to flat sections of roof using these frames.


What about the wind blowing the collector off the roof?

We take a lot of care ensuring that the frame and collector are securely fastened to the roof and will not blow away. If you want more detail on this, just ask – the methods for fastening to different kinds of roof vary depending on the type of roof.


Does the geyser have to go on the roof as well?

No, it definitely does not! If you are installing a pumped system the geyser can easily stay inside the roof or inside your home. If you are installing a thermosiphon system then the geyser needs to be above the panel. Usually this means putting it on the roof directly above the panel in what’s called a close-coupled configuration. However, if your roof has sufficient pitch it is possible to put the geyser in the apex of the roof space and still have it higher than the panel.


What are the advantages of having the geyser on the roof?

The main advantage of having the geyser on the roof is that if it ever bursts the hot water will run off your roof rather than through your ceiling and into your house.


Will my roof be able to hold all of that weight if I do decide to put the geyser on the roof?

When installing close-coupled systems we usually reinforce the roof.