Think of how much you have spent on electricity over the past 20 years. If I do some quick calculations, I must have spent close to half a million rand. Now, consider not having to spend another cent on electricity.
Itâ€™s tempting, right? And yes, it is possible to go completely off the grid â€” through a combination of enough solar photovoltaics, batteries and a generator.
I can understand why people want to be completely independent of Eskom and local utilities. Besides their monumental waste of money and mismanagement over many years, who would want to buy power from a utility that is unreliable, expensive and one of the worst polluters in world history.
However, here are two reasons it might NOT be a great idea to say goodbye to the grid.
In practical terms, letâ€™s consider the costs of going off the grid. The challenge is how to size your off-grid system correctly. You are going to need a lot of batteries, which will charge and discharge daily. For this you are going to have to spend more than R10,000 per kilowatt-hour â€” for a good-quality lithium-ion battery and inverter set.
Lithium-ion batteries are essential for long life. You want a 10-year warranty, with a minimum of 5,000 cycles. If you have a three-bedroom house, like ours, you may need about 30kWh storage. So, thatâ€™s already R300,000.
Then you are going to need to buy enough solar panels and inverters to charge them. Thatâ€™s about 7kW, as 1kW of solar panels in South Africa will generate, on average, 4kWh per day, depending on location, cloud cover, time of year, etc.
For an all-in solar and quality power electronic system with installation and maintenance costs, youâ€™re looking at about R20,000 per kW, so youâ€™re at around R140,000.
So, thatâ€™s R440,000 invested, including VAT.
Now comes the difficult part. Solar and batteries are good for your electronics, lighting and refrigeration. But not too good for your energy-hungry appliances such as your oven, hot plates, microwave, kettle, toaster and hairdryer, not to mention your old borehole, pool pump and underfloor heating.
For long stretches of cloudy days, or downtime on your system, you will need a generator and fuel as backup. And you may need to invest in superefficient water heating equipment, such as a heat pump, solar geyser or gas geyser. Together with the generator, gas oven and more efficient lighting, you can probably budget another R50,000-R100,000. Now youâ€™re in for around R500,000; maybe more. Donâ€™t panic, there is another way.
Hybrid systems â€“ i.e. grid feed-in solar combined with energy storage â€“ make the most sense for many homeowners. Hybrids reduce the costs of grid energy while providing a backup when required, and balance the best source of energy available at that time.
And you can scale them to your budget, your immediate requirement and invest more as you go on. The difference here is that, rather than going completely off the grid, youâ€™re using the grid when you need it and you have a backup option when itâ€™s not available.
The economic way to do this is to decide how much battery storage you need for a typical load shedding period of 2.5 hours. Which will be more like 1kWh to 4kWh, depending on whether you want to power your whole house or just your home office.
Say you decide to spend about R40,000 on a 4kWh battery system. You can then decide how much solar you want to invest in, which will effectively produce a certain percentage of your electricity each day.
That same percentage is what you should save on your electricity bill.
Right now, with interest rates at their lowest in decades, you can borrow cheaply from your bank and prepay your power with solar. I recommend putting as much as 4kW, about twelve 330W panels. That would be about R80,000, using the same costs as above. In this scenario, youâ€™re in for about R120,000, much less of a commitment than the aforementioned half million â€“ and youâ€™re doing your bit to save the planet.
There is no need for a generator or changing your appliances or when you use them. You will just need to check that your local municipality allows small-scale embedded generation (SSEG), but most in South Africa do.
Finally, a more philosophical argument as to why we should not go off the grid.
We use roads, water and other public services in South Africa. We all want better policing, health, education and national parks. We also use private networks such as fibre and telecoms. Why then would we cut off our linkages to the electricity network?
Surely a more engaged citizen would want to help to improve on our public services and grid network rather than delink from them. In addition, whether we like it or not, our Eskom and municipal bills cross-subsidise poorer users and other basic services in our cities.
The government is committed to transition to a low-carbon future and has already signed more than R200 billion worth of renewable energy contracts, some of which are already built and feeding into the grid.
Just as we should vote and pay taxes, we have some obligation to the betterment of infrastructure for all, not just looking after ourselves. We will not solve our larger problems by making more exclusive enclaves and higher walls. Are we in this society together? BM/DM