Date:24 July 2013
Robust, locally developed hybrid Novasun solar water heating system gets set to shine.
Soaring electricity tariffs and an over-burdened national grid – it’s no wonder many budget-conscious, blackout-wary homeowners are opting for solar geysers. This makes perfect sense: after all, domestic geysers are responsible for up to half of our monthly electricity spend, and the one thing our country has in abundance is sunshine. Right?
If only things were that simple. Although solar water heating systems and our sun-drenched skies theoretically make for a perfect match, in practice, there are a few drawbacks for the unwary. First off: most solar water heating systems require regular care and maintenance to remain in optimal operating condition, and because many homeowners tend to forget about them once they’ve been installed, failure rates tend to be high.
Even diligent maintenance doesn’t guarantee that you’re able to enjoy a hot shower for the foreseeable future; one decent Highveld hailstorm can demolish your system in under a minute. The uncomfortable fact is that our region’s unique set of environmental conditions make strong demands on solar heating systems, and until now, the only designs available were conceived in climes very different from ours. The obvious solution was to develop a system from scratch – which is exactly what Gauteng’s Etienne Holder has done with his newly patented Novasun solar water heating system.
With over 15 years in the geyser manufacturing game – much of it spent working closely with solar manufacturers and installers – Holder has an intimate understanding of the issues facing current solar water heating (SWH) systems. He explains: “As solar became more popular, we began noticing the shortcomings of imported systems. We have one of the highest radiation levels in the world and, as most SWH systems available here are best suited to colder European conditions, they take an absolute hammering.”
The list of things that can go wrong is a real eye-opener. Stagnation, where the system overheats because of underuse, is a huge issue, especially for evacuated (EV) tubes. Holder elaborates: “Runaway heating can cause internal temperatures to rise as high as 200 degrees. Apart from creating a serious safety hazard, this degrades the insulation around pipes, drastically reduces the life of the water cylinder, and ultimately, wastes water by causing the safety valve to open and dump it on to your lawn.”
At the opposite end of the scale, as ambient temperatures drop below zero, is the issue of freezing. This causes water trapped in flat-panel systems to expand and pop their copper channels. Then, when it gets warmer, you effectively end up with an expensive, leaking sieve bolted to your roof. Says Holder: “In 2010, one company alone lost a few hundred systems due to a big freeze. It had a huge impact on the solar and insurance industries as a whole.”
To overcome the problem, indirect heating systems – where the panel is filled with an anti-freeze solution that passes through a heat transfer unit – were developed. However, the antifreeze needs to be topped up on a regular basis and replaced biannually, which adds to the hassle factor. There’s also a drop in efficiency of at least 30 per cent because the water’s not heated directly. Says Holder: “This means that much of the electricity savings you’re supposedly making by purchasing the unit get ploughed back into the system to keep it running.”
Water quality’s a big problem, too. “You just have to read the newspapers… our water quality is deteriorating. Many areas now have very high levels of dissolved solids in the water, which blocks pipes in the panels and renders them ineffective. To remove the sludge, we have to disconnect everything and flush the system with mild acid. It’s a huge job. Even then, we’re lucky if we manage to get half of it out. Municipalities are also forced to add excessive amounts of chlorine to the water to kill bacteria; this plays havoc with stainless steel components.” Lastly, the complexity of many systems doesn’t make for easy installation, which confuses both the installer and homeowner. Says Holder: “The only folk who seem to understand them are the manufacturers.”
According to Holder, most consumers are caught between a rock and a hard place. “Cheap systems are financially accessible, but don’t last long. And good systems are so prohibitively expensive that any chance of you recouping your costs over the guarantee period is highly unlikely.”
Realising the only real option was to develop a local solution, Holder began applying his mind. Working with his long-time business partner Walter Hupertz, his goal was to create a system that didn’t stagnate or freeze, was hailresistant and cost-effective. It also had to be totally maintenance-free, easy to install, and “something he could guarantee for a long period of time”.
After two years of effort, they got it right. Says Holder: “Truth be told, we first thought EV tubes were the answer. However, because they were designed for arctic conditions, they’re just too efficient. Most people prefer flat panel collectors, but these also have serious drawbacks.” Eventually, the two men settled on a combination of the best attributes of both to create a completely new hybrid system. “Basically, we took inspiration from EV tubes, took ideas from flat panel designs, then threw our own five cents’ worth into the mix.”
Inside its flat panel collector, the Novasun system features thin copper tubes, all of which have been laserwelded on to the collector sheet. Inside each of the hermetically sealed tubes is just 7 ml of fluid, described as a “special mix of herbs and spices” that eliminates any possibility of freezing. As the fluid heats up, it becomes a gas, rising to dissipate its heat into a heat exchanger and warm the water. The gas then condenses and falls to the bottom of the tubes and the cycle is repeated. Once the water inside the heat exchanger reaches a temperature of about 65 degrees, the gas can no longer condense and the cycle is halted, preventing stagnation.
The unit is enclosed by a sheet of low-iron boron glass, making the entire collector completely hail-proof. It’s connected to Holder’s proven Solartherm water cylinder, which employs a crosslinked polyethylene (PEX) lining to prevent any grime build-up from dirty water. The complete system is reportedly very easy to install.
The Novasun SWH system has been awarded the SABS mark of approval and is already on Eskom’s rebate system.
A 200-litre unit is expected to cost around R17 500 (including installation) and comes with a 10-year unconditional guarantee.
For more information, contact Solar Assist on 0861 106 618 or visit www.solarassist.co.za