What does ‘off the grid’ really mean?
Essentially, it’s about producing enough alternative energy so that you do not need to rely on an energy provider. But it is not only in South Africa where energy supply is erratic and unreliable. The search for alternative energy sources for homes is an international trend, driven by people who want to reduce their carbon footprint and have a more environmentally friendly home and lifestyle, as well as reduce their living expenses.
There are three main alternatives to sourcing electricity from the national grid: solar-generated, gas power and wind power – or a combination of these. Eskom encourages homeowners to take up options that lessen the burden on the national
power grid, for example installing solar water heaters or moving to LPG gas-powered geysers, stoves and heating devices.
Is it practical?
“If you have deep pockets, then certainly you can do it. In reality, though, most homeowners will only be able to partially reduce their reliance on Eskom”, says Angus Fleming, Director of Sustainable Building Solutions. He explains that there is a significant financial implication if you want to get off the grid purely because of frustration with Eskom. However, for someone wanting to reduce their carbon footprint for environmental reasons, then the ‘greenness’ of the solution often outweighs the financial aspect. In the short term, costs can run to upwards of R100 000, depending on the specifications of the system you opt for. But in the long run it may ultimately prove cheaper and far more sustainable.
Where do you start?
Most households start with water heating. Your geyser uses up to 60% of household electricity, so it makes sense to minimise or eliminate that source of power consumption first. Solar water heating is the obvious place to start – but be aware that this is completely different to solar-powered electricity generation.
“Solar water heating is becoming far more common,” notes Angus. “I believe that it’s worth doing, especially with load shedding becoming a regular occurrence.”
Depending on your requirements, you can either use solar water heating to supplement your conventional electric geyser, or completely replace your electric geyser in providing your total hot water allocation. The latter approach is recommended by the experts from www.sustainable.co.za.
It’s worth noting that, although Eskom has previously offered rebates on solar water heating systems installed by an accredited supplier, as of 1 February this year the rebate fell away because the programme is now being managed by the Department of Energy (DoE). At the time of going to print, the DoE’s plans for the solar heating programme had not yet been announced.
If your budget doesn’t allow you to take your water heating entirely off the grid, there are other alternatives.
“Where cost is
the deciding factor, I always suggest gas for water heating, as this uses virtually no electricity and is relatively cheap – with the added benefit of being a clean source of heat,” recommends Angus. “If your budget is larger, then solar water heating, with gas as a back-up, is the perfect solution.”
According to the UN Environment Programme, South Africa is the world’s third-best location for generating solar power, which makes solar a good option for households. Eskom agrees, pointing out that the intensity of our radiation is almost twice that of Europe.
Solar panels are a key component of any solar-powered system. In its simplest form, a solar panel consists of an array of photovoltaic (PV) cells which generate a direct current from sunlight. The heart of the system is an inverter, which converts the direct current to alternate current and manages the charging and discharging of the battery bank. The latter acts as a power storage facility that can be used when back-up power is required. In domestic households, this is usually at night or during poor weather.
As previously mentioned, the upfront cost of a system capable of running a domestic household completely off the grid is very high and requires significant battery storage facilities. But for those less concerned about budget, Angus recommends solar PV cells with a battery back-up. If it’s possible and you have enough wind, you could consider a hybrid PV/wind system. However, he cautions that batteries are the Achilles’ heel of solar PV systems because they need to be replaced approximately every five years and the replacement cost is high.
There are usually 10 batteries in a solar PV system, but if one fails the entire set needs to be replaced. The good news is that as its popularity increases, the cost of solar PV systems is declining.
However, says Angus, it is possible to install a solar system that would decrease your energy requirements and take you partially off the grid – using some solar panels and an inverter – for about R30 000. “The reality is that if you know when load shedding is taking place and you can plan for it, you only need a system capable of running for four hours at a time. This is not massively complicated as you don’t need to run your entire house during that time,” he explains.
Some residential areas in South Africa have access to piped town (natural) gas, while other households use bottled LPG gas. Running a geyser using natural or LPG gas is a simple, affordable option.
“The new electronic gas water heaters on the market are very efficient,” Angus advises. “You can install a solar water heating system with a gas water heating back-up for those days where the water is not quite hot enough. Then you really have the best of both worlds.”
He adds that LPG is increasingly popular for cooking and space heating, with a growing number of people also opting for water heating with LPG because it doesn’t require a large quantity of gas. As an example of the affordability of gas, if you run only a kitchen hob off LPG gas, a 48kg bottle will last approximately 15 months.
Gas generators are now also on the market as a back-up to mains electricity. “A gas generator is a good solution as it is relatively cheap and cost-effective to run, as well as being far quieter than a diesel generator and with none of the fumes,” advises Angus.
Can I retrofit?
You can retrofit, he says. Although new builds provide a great opportunity to be proactive about reducing energy consumption and installing passive systems, Angus also sees many homeowners including alternative heating and energy generating systems during the renovation process.
It’s fairly straightforward to convert a standard electrical geyser to either gas- or solar-powered water heating, or to install a gas stove in place of an electrical one. However, in both instances the installation must be completed by an accredited installer for both safety and insurance purposes.
Passive power saving strategies
Even if you can’t get completely off the grid, there are many easy ways to save power without having to renovate your house, advises Angus Fleming of Sustainable Building Solutions. Among them:
Get it touch
Eco-Eye: 0861 001 106, website www.eco-eye.co.za
Efergy Electricity Monitors are available locally through www.sustainable.co.za
OWL Electricity Monitors: (011) 386 0000, website www.theowl.co.za