It is estimated that 50% of solar panel systems in South Africa fail within two years of installation. Sarah Allan, owner of a 21ha farm at Curry’s Post in the KwaZulu-Natal Midlands, learned this the hard way, having installed both solar and
wind systems that failed to deliver on their promises. But through perseverance and teaming up with reputable providers, she is now living and farming entirely off the national power grid.
Sarah, who has lived on Easter Woodend farm for 16 years, has 3ha planted to wine grapes – shiraz, chardonnay and merlot – and flame seedless table grapes. She also runs a small herd of Ngunis and a patch of wattle and gum timber. When the first major electricity price increases loomed in June 2010, Sarah decided to switch to renewable energy (RE).
“Not only was Eskom looking at significant tariff increases, but its supply was becoming unreliable, with load-shedding and unplanned outages,” she recalls. “I thought it would be far more reliable to become self-sufficient.”
Sarah’s first foray into RE was with wind energy. In mid-2010, she installed a turbine generator, but it simply failed to work. “I had been told to erect it 5m off the ground, but later learned that a turbine needs to be at least 9m above the nearest obstruction to ensure that wind flow is not obstructed,” says Sarah.
At the same time, she installed a four-panel solar array at a cost of R12 000. A solar array is a series of photovoltaic panels linked together and operating as a single power source.
“Unfortunately, the panels didn’t meet my expectations either,” Sarah recalls. “It wasn’t positioned at the correct angle to the sun and there were problems with the wiring too.”
A direct lightning strike then burned out the electronic equipment, abruptly ending the turbine’s life. Using the insurance payout, Sarah raised the height of the mast to 21m and installed a second turbine generator in September 2011. She also employed KwaZulu-Natal based company AdSolar EPC to upgrade the electronicsystem. This involved installing an eight-panel array and switching from 12V batteries to 2V cells, which have a longer life.
However, the turbine again failed to deliver the promised output. Two months later, the solar array was extended to 14 panels, and three months after this the turbine was replaced by a more powerful 1 000W model.
Finally, the system began to deliver as promised. The energy mix of wind, solar and a backup generator to charge the batteries on windstill, gloomy days provides sufficient power for the farm and homestead’s requirements. Sarah cut the Eskom ‘umbilical cord’ two years after starting the project. “The turbine is excellent,” says Sarah. “It holds its position, pointing into the wind, until the battery is fully charged and then moves out of the wind.
The solar array, which moves every few minutes as it tracks the angle of the sun, now generates about 3 000W of power.” The combined output of the solar array and the wind turbine is sufficient to charge 762 ampere hours of batteries, which translates to about one and a half days of power. This fulfils all the needs of the farm and household. The system powers all the household appliances, including fridges and freezers, lights, an inverter welder, an angle grinder and a small 600W irrigation pump, among other equipment.
“The entire RE system, including the turbines, solar panels, building, cabling and replacement of certain household appliances, costs about R250 000,” explains Sarah. “It’ll take about six years to recover the capital outlay, based on what I was paying previously. Fortunately for those who plan to install an RE system in the near future, the cost of the major equipment items needed is decreasing as demand increases.”
At a cost of R75 000, the batteries were the single most costly item. “Because they’re so expensive, I want them to last as long as possible,” says Sarah. “So once a month I equalise them, which involves increasing the voltage so that the batteries’ contents bubble vigorously. This redistributes the lead evenly, which extends battery life.” A 1 000W wind turbine costs about R20 000 and the tracking system for the solar panels is priced at R14 000. But it is the hidden expenses that can catch the buyer unaware.
“For example, the mast has to be embedded in a 1m3 foundation of vibration-stressed concrete. This costs about R4 000,” explains Sarah. Lightning protection is another unexpected expense. “Because the mast is so high, it’s an ideal conductor. After lightning destroyed the first turbine, I had to install a lightning protection system for both the mast and turbine to satisfy the insurance company. I also put in two gas arrester boxes, which cost about R7 000 each.”
One of the most important aspects is to get the design of the solar array 100% correct. According to ADsolar EPC project director Lloyd Wilford, the site should be studied in detail. “One needs to consider where the shadows fall in summer and
winter,” he stresses. “So the inclination and orientation of the solar array is crucial. Reflected, diffused and direct light also affect power output. We even look at the average temperatures for the past 20 years when designing a system.”
Code of conduct for solar indistry
Lloyd points out that the solar industry is still in its infancy in South Africa and picking a reputable EPC company can be difficult. “Everyone promises the world, but more than 50% of solar installations fail within 18 months,” he says. The industry is in the process of introducing a code of conduct and a set of minimum standards to give customers greater peace of mind.
“We’ve established the Southern Africa Solar EPC Companies professional network and are trying to foster closer relationships between EPC companies that stick to minimum standards,” he explains. “When selecting an EPC company, go for one that has a traceable track record of no less than two years and speak to five or six former customers.”