

The result: The On-Sun South African Solar Water Heater! The On-Sun is a unique product, unlike any other solar water heater on the market
Today the On-Sun is the only freeze-tolerant, flat plate, direct system (no anti-freeze, pumps or valves) solar water heater made in South Africa!
What are the Advantages of the On-Sun system?
Here is a system that was installed on the ablution block of the Sehlabathebe Farm Training Centre in Lesotho in April 1992, and that is still going strong 18 years later!
If you have an existing electric geyser in good working condition, we recommend that you leave it in place and instal the On-Sun solar water heater in series to supply the geyser with water heated by the sun. Not only will this save you significant amounts of electricity, it also increases the total capacity of your hot water system. In such an installation the heating element of the On-Sun is not connected to the mains. This has the advantage that no new electrical work is required and therefore no new Certificate of Compliance needs to be issued by an electrician, which saves you money on the installation. On its own, an electric geyser of 150 litres with the thermostat set to 55 degrees C (recommended temperature that is adequately hot for bathing or showering) will use 6.1 kilowatt hours (kWh) to heat the water from say 20º (the incoming temperature) to 55º. Here is the calculation: 150 litres x 35º = 5 250 Kcal / 860 = 6.1 kWh In winter the incoming water might only be at a cold 5ºC, in which case the geyser will use 8.7 kWh to reach 55ºC. That’s a lot of energy! Here is the calculation: 150 litres x 50º = 7 500 Kcal / 860 = 8.7 kWh But if the incoming water is at a warm 40ºC, the geyser will use only 2.6 kWh to warm it to 55º C Here is the calculation: 150 litres x 15º = 2 250 Kcal / 860 = 2.6 kWh So you can see that warming the water supplying your geyser always reduces the use of electricity. The warmer the incoming water, the less electricity required to raise the temperature to 55ºC. As soon as the incoming water is at 55º C or higher, the thermostat will not switch on at all. This is how the On-Sun installed as a pre-heater works. On a sunny day hardly any electricity will be consumed by the geyser because the On-Sun will feed it with water above 60º. And even if it is cloudy the next day, there will still be warm water in the solar water heater so that the geyser element has to do less work to get the water temperature up to 55º C. We always insulate the piping carrying hot water from the solar water heater to the electric geyser with foam rubber sleeves. We recommend that your electric geyser should be fitted with a suitable insulating blanket, and that the hot outlet pipe of the geyser be fitted with a 1 metre insulating sleeve to reduce thermal loss. If your electric geyser does not already have an insulating cover fitted, we will do this for you at no charge at the time of installation. 
Lesotho has one of the harshest climates in Africa.The annual total solar radiation over the country is estimated to be between 5,700 MJ/sq m and 7,700 MJ/sq m. Temperatures are highly variable on diurnal, monthly and annual time scales. Normal monthly winter minimum temperatures range from -6.3 degrees C in the highlands to -5.1 degrees C in the lowlands. However, extremes of monthly mean winter minimum temperatures of -10.7 degrees C can be reached, and daily winter temperatures can drop as low as -21 degrees C. (Source: Lesotho Meteorological Services: www.lesmet.org.ls).
The On-Sun system is available in 100 litre, 150 litre and 300 litre configurations, operating at water pressures of either 100 kPa or 200 kPa. The most popular model is the one-piece On-Sun 150 litre 200 kPa system. This is the only On-Sun system that has passed all the SABS tests required for admission to the Eskom subsidy scheme.
Further variations include a 150 litre split system (the On-Sun 202) where the collector and tank are closely coupled by six standard connectors. The benefit of this configuration lies in simpler transport, an aluminium collector tray, and better safety on high roofs for the installer.
The On-Sun systems are available in a variety of tank covers, ranging from our standard galvanised steel (very durable and long-lasting in the high interior of South Africa), to aluminium for coastal areas, to stainless steel (for smart appearance everywhere!), and to Chromadek coated steel.
Please note that special tank covers cost extra, and are made to order. Stainless steel and stucco aluminium tank covers are available on order for single units; coloured Chromadek tank covers are only made for special orders of ten units or more, and by arrangement with the factory.
The standard galvanised steel tank covers can be painted to match roof colours. Please see our gallery below for some examples of painted tanks.
Computer-designed steel frames can be made up to provide the correct orientation on any roof slope. Below is a system recently installed on the west-sloping roof of a house built by a Korean businessman in Ladybrand. As Willi Suremann says "The wise man from the East has installed a product designed and made locally for local conditions!"

The On-Sun for Institutional Water Heating
As noted above at the Sehlabathebe Farm Training Centre, the On-Sun can be installed as multiple systems to provide large amounts of hot water for institutions. The photo below shows one of Willi Suremann's latest installations for a facility in Maseru, where a total of 10 x 150 litre units have been fitted to the roofs.

On-Sun has a Royal client!
I was searching the web for some information about Lesotho when I found a video feature about Prince Harry at an AIDS orphanage he has helped to sponsor in Maseru, Lesotho. He has a special interest in Lesotho and has visited the country many times.
As the Prince was being interviewed in front of the building, the On-Sun solar water heaters on the roof behind him were clearly visible! I think we can justifiably claim that Prince Harry is yet another of our esteemed On-Sun clients!
On-Sun complies with all four SABS Tests for the South African National Solar Water Heater Standards required by Eskom
SANS 1307 is the standard for exposure, rain penetration, hail resistance, freeze resistance, marking and the 250 000 pulsation test.
SANS 6211 is the standard for thermal performance (Q factor) and heat loss. The Q factor for the On-Sun 150 is 16.412 Megajoules at 16 MJ.
SANS 151 is the standard for fixed electric water storage heaters.
SANS 60335-2-21 is the standard for the safety of household and similar electrical appliances. Part 2 covers the particular requirements for storage water heaters.

The ON-SUN solar water heater fitted as a pre-heater to your existing geyser
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SOME FEATURES OF THE ON-SUN SOUTH AFRICAN SOLAR WATER HEATING SYSTEM

The On-Sun has a very clean and neat appearance, as all the water controls are contained within the tank cover. The standard tank cover is galvanised steel, which can be painted to match the roof colour if required. Tank covers are also available in stucco aluminium or stainless steel. This is a standard 150 litre model, fitted flat on a north-facing pitched roof.

This On-Sun 150 litre unit is mounted on a steel frame on a flat roof, to achieve the correct orientation (true north) and tilt (35 degrees from horizontal at a latitude of 25 degrees South).

On-Sun mounted on the ground in 300 litre configuration. Here we use a special matched pair of 150 litre units that are closely connected in series. A cover over the connections makes for a very neat appearance, with no piping visible. Note the solar cooker in the background! We can supply these 2 square metre super solar cookers on request: our price is around R2 000 - very competitive and good value for money .
The On-Sun 100 litre system is well suited for low cost housing, providing a quality product at an affordable price. This system is installed on an experimental RDP house on the campus of the University of the Witwatersrand, Johannesburg.
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I have been marketing and installing the On-Sun South African Patent Solar Water Heater in Gauteng, South Africa, for seven years now, and I have learnt to appreciate the very special qualities of this unique product.
We have installed On-Sun systems in Greylingstad and Nelspruit in Mpumalanga, Ventersdorp and Lichtenburg in North West, Pretoria in the north, and Meyerton in the south of Gauteng. We prefer to work in Gauteng, but remember that the On-Sun is easily installed by any plumber or handyman, so you can always pick up a unit from us and DO IT YOURSELF!
You can contact me by telephone at 011-680-1553, by mobile at 083-650-1768, by e-mail at John.Ledger@wol.co.za. Give me a call any time of the day, or leave a message if the line is busy. I enjoy talking to folks about renewable energy!
I also have an electronic brochure that gives further information about the On-Sun solar water heater, and it will be my pleasure to e-mail it to you on request.
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SOME RECENT INSTALLATIONS OF ON-SUN SOUTH AFRICAN SOLAR WATER HEATERS

113 Seventh Street, Linden
When a satisfied client orders a second On-Sun because the performance of the first is so good, we really feel proud of our product! Mrs Kirsch installed an On-Sun 150 litre system for her kitchen, scullery and outbuilding. It worked so well that she ordered a second one for her bathroom. We installed an On-Sun 150 202 split system close to the first. This house is now harvesting a significant amount of thermal energy from the sun, and cutting electricity costs! Mrs Kirsch is helping to reduce South Africa's coal and water consumption for electricity generation, and preventing significant amounts of carbon dioxide and other pollutants from entering the atmosphere every year.
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21 First Avenue, Houghton
We installed three systems for a client in Houghton, Johannesburg. One standard 150 litre On-Sun was mounted on a frame on a horizontal concrete roof as a stand-alone supply with electric backup to a flat (we removed the existing geyser). A 150 litre 202 split system was installed on the main house as a pre-feed to the electric geyser, and a 100 litre system was fitted onto the roof of a patio next to the swimming pool, to supply hot water to an outdoor shower and a hand basin. The tank covers of the latter two systems were painted by the client's handyman to match the terracotta colour of the tiled roofs. He did a really great job!
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14 Roxburghe Road, Craighall Park
Two On-Sun 150 units were installed, one on the main house (left) and the other on the outbuilding. The main house system was mounted flat onto the slate roof, while the system for the outbuilding was mounted on a steel frame to get the best inclination for year-round performance.
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31 Denton Place, Mondeor
On-Sun 150 system installed on a steel frame on a back-sloping IBR roof with loose tiles on top.
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17 Chamfuti Street, Sharonlea, Randburg
This On-Sun 150 has been painted to match the green tiled roof of the house. Water-based primer and roof paint from Prominent Paints was applied, after the tank cover and tray were thoroughly cleaned with galvanized steel cleaner and the fibreglass end-caps sanded with water paper. The paint is guaranteed for 7 years and the On-Sun can be touched up whenever the roof is repainted. The green solar water heater blends well with the roof, the awnings and the greenery of the garden. Because all the water controls, including the vacuum breakers, are housed inside the tank cover, we do not have insightly pipes projecting above the system.
The On-Sun is the only flat-plate, freeze-resistant, direct solar water, without special pumps or valves, on the South African market. The SABS test for freeze tolerance requires the system to be cooled to minus 20 degrees C and held there for 14 hours. With its 20 year pedigree in the snow and ice of Lesotho, the On-Sun had no problem with that particular challenge!
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21 Denton Place, Mondeor
This is the On-Sun 150 litre system in the "202" split configuration. The tank and collector are supplied as separate, matched units. This makes the system easier to transport and lift onto steep roofs. In this particular installation, we had to get our solar water heater to the top of three stories, each ringed by a high parapet. The 202 system is much easier to handle in such a situation, reducing the risk of damage and accidents. In this case the system is mounted on a steel frame, and the collector is joined to the tank with six Cobra Conex straight couplers. The small gap is closed with a stainless steel cover to give a neat finish.
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The Eskom SWH Incentive Scheme
Eskom's incentive scheme to encourage South Africans to instal solar water heaters has grown steadily since the beginning of 2008. To find out more about the scheme, visit www.eskomdsm.co.za and follow the links to Solar Water Heating. All the information you need about the programme is on this web site.
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ON-SUN Q and A
Q: Is the On-Sun South African Solar Water Heater currently accredited for the Eskom incentive scheme?
A: NO
The On-Sun 150 has passed all the tests for SABS 1307 (solar water heaters), SABS 6211 (thermal performance and heat loss), SABS 60335-2-21 (electrical safety) and SABS 151 (Fixed electric storage water heaters). All four tests are mandatory for entry to the Eskom incentive scheme.
Q: Do you expect the On-Sun system to be on the Eskom suppliers' list soon?
A: NO
Our system is competitive without a subsidy, and our customers make the choice. Participation in the Eskom subsidy scheme requires additional paperwork - someone has to pay for that.
Eskom demands that its accredited suppliers obtain the SABS mark within 12 months of being registered. For a small business like ours, the cost of obtaining the SABS mark is prohibitive. We would have to charge a lot more for our products.
As recent events have shown, SABS marked and Eskom-approved systems that qualify for the subsidy have failed during the recent cold spell in Gauteng.
Eskom approval and a subsidy are therefore no assurance that you will necessarily get a durable product, or that your supplier will be there to honour the five year guarantee.
Eskom has made it very clear that its subsidy scheme will reduce to nothing over the next five years. Furthermore, Goverment wants to take over the solar water heating initiative from Eskom for political and social motives.
As Africans we complain about agricultural subsidies in the EU that prejudice our food exports to Europe. How then do we expect to build a viable solar water heating industry on the basis of subsidies?
At the moment we have enough interest in the On-Sun to allocate our limited production to discerning buyers who want a unique and proven South African product that provides jobs for South Africans and uses local components.
The On-Sun is very competitively priced and can match most comparable systems that qualify for the Eskom subsidy - and then there is our 20-year track record that comes at no cost!
If you are not satisfied with your On-Sun solar water heater, let us know within three months and we will remove the system and refund your money in full. No arguments, no lawyers, no harsh words. That is just the way we want to do business with you!
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Best wishes
John
20 August 2010
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