Every now and then people are killed and injured by geysers exploding. Experts warn that the probability of disaster increases as more of us switch to solar geysers. Solar geysers are air-friendly and can save money, virtually a must in sunny SA. But they generate much higher water temperatures than normal electric geysers. On a hot summer's day, they can easily get to boiling point, which makes a safety valve essential.
By law, water delivered to the hot tap in a bathroom may not exceed 55 degrees Celsius. The solution is a simple R450 thermostatic control valve that adds cold water when the temperature gets too high. To save the money, some installers simply don't fit the valve. Solar systems require specialist skills to install them. SA has only 4 830 registered plumbers and, according to the SABS solar testing team, only about 700 are in a position to issue certificates of compliance on solar installations.
Indeed, the shortage of qualified and experienced installers is the main reason that Eskom's discounted scheme has been slow to take off. Barry Paul of the SA Bureau of Standards solar lab says: "It takes 20 seconds to sustain third degree burns with water at 60 degrees. At 85 degrees it takes three seconds." Karel Deist of the SABS solar laboratory says: "Clause 10 of the Occupational Safety and Health Act regulates the safety of these systems and adherence to SA National Specifications is compulsory." Some investors, who want to import or produce cheap solar systems, complain that "specifications are a trade barrier".
After testing more than 500 systems in the past five years and finding many sub-standard or faulty, the SABS team is adamant the specs are vital for safety and consumer protection. Deist says:"I don't want to put people off solar geysers. In our sunny climate they make complete sense. We just want buyers, sellers and the installers of these systems to be aware of the pitfalls." People who have high quality systems properly installed are delighted with them. But it is possible that some are sitting on a timebomb. That is why, to qualify for its rebate, Eskom insists on SABS-tested systems and installers who can issue certificates of compliance.
Installing a solar system is complex. You have to bleed out the air and make sure that it is correctly piped and pitched at the correct angle to the sun. Some are split systems that require a small 12-volt circulation pump, sometimes powered by the sun, sometimes by mains power. Others are "thermosyphonic" and circulate water by convection. Wrong installation can destroy the efficiency of the best system. A drip tray, vacuum breakers and a safety valve are mandatory. It will not be easy to train the army of competent installers required for a million new systems - Eskom's big hope. Says Deist: "I reckon that, to be called competent, a person must have installed ten systems correctly himself. A qualified person needs to stand behind him and make sure he's doing it correctly. It's very tempting to take a short cut."
As with motor cars, the most expensive systems are generally the best - but, as with cars, some middle-cost solar systems are of very high quality. Some cheapies are good but most are less robust and won't last as long. But no matter how good the components, a badly installed system will at best not be economical and, at worst, dangerous. Systems that pass the SABS test are pretty robust. They are subjected to pressure, hail and freeze tests. They are tested at minus 20 degrees to ensure they stand up to frost. And they are bombarded with hail stones the size of golf balls. They also undergo thermal testing. All of this takes up to four weeks.
Many sellers of solar geysers are claiming you can save 40% of your domestic electricity costs. That is true only of a low-income family. For those who have underfloor heaters, automatic dishwashers, tumble driers and who use their electric stoves and heaters extensively, the saving is perhaps only 20%. A solar system generally comprises a solar heat collector coupled to an insulated storage tank. The collectors are of two types - evacuated tubes and flat panels. The evacuated tubes are made of glass. Each has its advocates.
Barry Cribb MD of Sky Power, claims evacuated tubes deliver more heat. Based on a calculation of the energy required to raise the water temperature by 40 degrees, he claims that 54 of 139 products listed on the approved Eskom list deliver between 18% and 59% of the required energy from the sun. The shortfall is provided by electricity, which means those systems are uneconomical. A rival, Jim Hickey of Solahart, the market leader, admits that evacuated tubes generate more heat but he says SA has so much sunshine that evacuated tubes make the water too hot.
"They were designed for Europe."
His product comes from what he claims is the world's biggest solar geyser factory in Australia. Herman Strauss of the SA Bureau of Standards agrees that evacuated tubes deliver most heat. But he agrees that heat delivery in SA can be excessive. One competent installer said the flat panels are much stronger and proved his point with a mighty kick to a Power Zone panel that made no impression. Proponents of evacuated tubes say they are cheap and easy to replace if broken by hail, by an envious neighbour, or rioters throwing stones. But the installer said it is really hard, when there are fragments of glass in the insulation and in the O-ring seals to ensure a proper seal after a repair.
SABS may not recommend one make over another but Strauss recommends that before you buy you should ask for the supplier for the SABS test report. The SABS might pass a product but it gives its mark only after it has audited the manufacturing process. For the privilege of the mark producers can pay R60 000 - but Deist says testing is not cheap. Huge amounts of power are used and the laboratory equipment is worth millions.
To reduce demand on its power stations, Eskom in collaboration with the National Energy Fund, wants the maximum number of people to switch over and so offers a subsidy of up to 30% on an array of solar heaters ranging in price from R9 000 to R35 000. Its rebate is directly linked to the electricity saving of each system. Some SA manufacturers are cobbling together panels and glass evacuated tubes, which are mainly imported. Hopes are high that a local industry will develop. Eskom's rebate scheme takes into account local content. Hickey says there is no way SA manufacturers can compete with those in China, or even the 50ha plant that Solahart has in Australia.
"There will be job creation but it will be among installers and maintainers. We need dozens of teams of six or seven people and I am sure it's true of all the players. That's where the jobs will come from."
By David Carte
Article Source: moneyweb.co.za
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