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Renewable energy for estates and homes

Whilst the topic of renewable energy deservedly garners plenty of modern headlines, most of us who’ve grown up in the age of fossil fuels would find it almost inconceivable that the world’s relentlessly escalating energy needs could ever be satisfied by renewable energy sources alone. It might come as a surprise, then, that some leading scientists say the technologies already exist today to make such a scenario feasible.

A review paper published in the highly respected journal Renewable and Sustainable Energy Reviews in 2017 (written by environmental consultant Benjamin Heard and colleagues) cast doubt on that possibility, but met with many a riposte from the global scientific community. These included a former employee of South Africa’s Council for Scientific and Industrial Research (CSIR), Dr Tobias Bischof-Niemz, who said: “It’s beyond any scientific doubt that a renewables-led energy system is technically feasible, and recent technology cost developments for solar and wind have now made it economically viable too. Good news indeed for sun- and wind-rich countries like South Africa.”

While the scientists and environmentalists argue their cases, there are undoubtedly many economic and political hurdles between now and that Utopian future, but the cost of renewable energy solutions is falling ever closer to that of more ‘old-fashioned’ energy sources. BP (British Petroleum), of all people, has estimated that wind, solar and other renewables will account for about 30% of the world’s electricity supply by 2040, up from about 10% today.

Barriers to adoption

So if the whole world really can be powered by renewable energy, surely a little residential estate should be easy, right? Unfortunately not. While individual homeowners might choose to install solar photovoltaic (PV) systems for when there’s load shedding or a power failure, for an entire estate to harness its energy requirements from solar, and particularly their crucial security systems, would require that a large area of the property be dedicated to solar panels.

Some estates do have solar solutions installed, but they are more commonly used in conjunction with houses’ geysers to save energy by regulating their water temperature (Balwin Properties teamed up with SolarAfrica in 2017 on just such a system in two of its up-market estates). More extensive renewable energy systems are not only expensive, they also tend to offend many residents’ aesthetic sensibilities. The Meyersdal View Nature Estate ran into precisely this problem a few years ago when homeowners objected to the unsightly and noise-producing wind turbines installed on the property.

Don Drennan

Don Drennan, owner manager of power solutions provider Drensky Technologies, is by no means opposed to solar solutions, but warns that there are some caveats. “We have been looking more and more into this over the last couple of years and we have worked on some solar solutions, and one thing I have realised is that more capacity is generally needed than originally anticipated. I know of sites that have tried to go completely off-grid and failed, only to have to rely on Eskom as a backup despite their best efforts.”

The most obvious reason why less solar energy than anticipated might be harvested is climatic conditions such as cloud, mist or rain. Less obvious is the fact that even when the sun is shining, some of that solar energy is being used to keep the backup batteries charged, in addition to what is being used to supply the immediate power requirements of connected devices.

“Storing the energy is often cited as very expensive, but now we’ve got lithium based battery technology which is much more robust to cycling, handle heat better without derating, have a better discharge rate, and can discharge down to virtually nothing. On the other hand, these batteries are much more expensive than alternatives like lead-acid or gel batteries, so an option is to only run critical systems on solar during the day,” Drennan says.

Another important factor is that power is used differently by different people and different estates. People who work from home will use power throughout the day while office workers’ usage will peak before and after hours; some people shower in the morning while others shower at night; and so on. “What you really want to do is conduct a proper energy analysis over at least 10 days to see how they’re using their power, and then design the solution around that,” Drennan advises.

For those estates and homeowners keen on considering a solar solution, there are companies who can assist.

Many options available

One such company is Specialised Battery Systems, based in Johannesburg’s East Rand, which offers the SBS Solar brand in South Africa. “With failing infrastructure and unreliable electricity supply, security systems and powering them has never been more important. So having either an independent power supply for your security equipment or a backup power supply is imperative in today’s world,” poses Colin Mackay, head of alternative energy/solar. “SBS Solar has a range of solutions to provide power, save on costs and above all provide peace of mind.”

Among the range of solutions the company provides are DIY solar lighting solutions, comprising products such as a 10 W solar security light with movement sensor, remote controlled area lighting, and standalone street lighting for gateways, pathways and common areas. Each of these is independently powered from a solar panel and a lithium or deep-cycle battery.

“The most critical areas in your home – electric fence, garage doors, gate motor, alarm system, CCTV system and security lights – are useless without power, and you are most vulnerable without them,” he continues. “Our range of standard and custom designed backup kits will provide power to these areas for as long as you need.” For instance, SBS Solar supplies a 5 kVA system that supplies power to a garage door, alarm system, light, electric fence and CCTV system (as well as TVs, fridges and other comforts) for 6 hours.

While a battery backup system supplies power for a limited time, Mackay says one of the company’s energy storage systems can supply power indefinitely. It does this by combining the battery with a solar system that can be connected not only to critical items, but to most of a household, and will reduce grid usage as well as supplying indefinite power for security requirements.

One solution the company has installed is a 5 kVA solar array supplying power to most of a household in Serengeti estate, taking care of its security as well as water purification, pumping and comforts. By way of another example, beyond the residential environment, it has also installed a system for a company that has all security lights, CCTV, alarms and electric fences more than covered for indefinite power outages. In addition, the 12 kW solar array provides power directly to the factory and offices – reducing day to day consumption by over 30%.

For more information contact:

• Don Drennan, Drensky Technologies, +27 31 940 0463, don@drensky.co.za, www.drensky.co.za

• Specialised Battery Systems, +27 11 425 3447, info@special-battery.co.za, www.special-battery.co.za

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