How to keep the lights on during load shedding

Every time ESKOM starts load shedding, people run around spending loads of money on anything they can get their hands on to have some form of power supply solution when the power goes off for four hours every day, sometimes twice a day.

The downward spiralling mains grid supply availability and reliability are getting worse every day. It is highly doubtful ESKOM will turn anything around in the next five or even ten years – if anything, the problem will probably get worse. South Africa has been plagued with ongoing grid power degradation and the poor availability of a stable power supply in the grid for well over ten years. Many people have already invested in some form of backup power solution. Those who haven’t are divided into two camps, people who can afford to invest in an alternative and, therefore, will do so in the future, and people who can’t. Those who can’t, will be forced to burn candles for many years to come.

What load can a standby power generating system carry?

Putting an entire household on an inverter, UPS or solar solution is unaffordable for most. You will want to connect only selected loads to your backup system. There are many household loads that should never be added to your backup solution as they make the system very expensive and impractical. For example, for all heating and cooking needs, rather invest in gas geysers, stove tops, and heaters. For cooling, invest in ceiling fans or normal fans that don’t use as much power as an air conditioner. A fridge that is left closed won’t get warm in four hours, and a freezer, if left unopened, will stay frozen for a day or two. It is generally a good idea to invest in low energy consumption lights and electrical appliances with the highest efficiencies and lowest power usage to minimise power consumption all the time and cut down on your electricity bill.

For gate motors, electric garage doors, alarms, and other loads with a built-in battery, it is advisable to rather put a bigger battery on them than to connect them to your backup power system. The installers of these products may tell you that fitting larger batteries doesn’t work, but at Standby Systems, we have 100 Ampere hour batteries on all our alarm systems and electric fences on our business properties, and they’ve been running for years without any problem. Yes, the chargers in these devices are small, but luckily rolling blackouts don’t last for weeks on end, so the battery will eventually trickle charge to 100% in time.

There are several backup power solutions one can opt for. The better solutions bear the greatest cost. The more common solutions for South Africans are:

  1. Generator
  2. Inverter
  3. UPS
  4. Solar


A generator is by far the best and most reliable solution. It doesn’t require sunlight to operate, it doesn’t have batteries that need replacement every few years like with inverters and UPS. Batteries on the latter backup systems need to be replaced due to failure, as they are used out by cycling. When generators give trouble, it is mostly mechanical in nature, electronic failures are rare and not catastrophic like with other solutions. Generators are also not susceptible to power surge damage like solar inverters are.

Yes, a generator uses fuel, it makes a noise—although on high-end models it is possible to have reasonably quiet sets, and they require maintenance and filter changes once a year or so. But these costs are very small by comparison to the initial capital investment, and also much cheaper than a professionally fitted solar solution which, after ten years, only produces 80% of its original capacity and degrades from there; or battery backup that requires replacement every 2000 to 3000 cycles (or even less depending on operational environment).

Unfortunately, a generator solution is not always possible due to rules about noise in complexes, housing developments, estates, and shopping malls. For many, the only solutions are the quiet ones.


There are many types of inverters on the market, with pricing ranging from a few hundred rand to several thousand rand. A typical home inverter is generally used to supply backup to a TV, a light, a decoder, Wi-Fi, and a laptop or PC for four hours during load shedding. The type of inverter technology supplying these devices is not really that critical as they are all fitted with power supplies that take AC mains power and convert it to DC power inside the device. In other words, whether the inverter is true sine wave or modified sinewave is of no relevance when it comes to these types of devices. Where the pure sine wave may be more crucial is in high-end electronics and laboratory devices.

The important thing to look at when purchasing an inverter is its ability to recharge the battery properly (it must have 10 or 20 amps recharge availability). Also, when choosing a battery, use a cycling battery that is sized correctly so that on every four-hour discharge there is sufficient time and power to recharge the battery in the next 20 hours. Otherwise, at the next rolling blackout the battery will not be fully charged, and a loss of backup time will be experienced over a few days. The result is people think the battery is failing when actually it just isn’t getting enough recharge power between backouts.

Everyone is jumping at Lithium-based battery solutions while being oblivious of the fact that, at the time of writing this article, there is no Lithium recycling facility in Africa. These batteries are landing up on landfills at end of life. Lithium battery products contain elements that are highly toxic, therefore they should not be disposed of in landfills as they will poison our environment and underground water supplies. The fact that a lithium battery can work between a very wide voltage range (even down to 0 volts) is of no consequence, as there are no inverters that can work within these wide voltage ranges as they are all limited by the electronics.

It is vital to make sure that your battery is sized to discharge a maximum of 30% of its rated capacity for four hours. A depth of discharge of more than 30% will end in disaster. This is where the cost comes into play with an inverter battery. One supplier will sell you a four-hour backup and yes, it will give four hours on day one or two but not continuously. Most of these unscrupulous suppliers are relying on the fact that the inverter will not be running at the calculated load and that rolling blackouts generally run for a few days and then grid power supply is available again. Don’t get caught out.

Another consideration with battery sizing is that, at 30% depth of discharge, how many cycles will a battery give you? A popular battery size is a 100 or 105 ampere-hour. There are several technologies in this range, and some will do only 300 discharges whilst others will do 3000. It doesn’t make a difference the technology of the battery or if it’s deep cycle or ….., the important thing is to purchase a battery that will achieve several thousand discharges at the same depth of discharge cycles as another battery product.


A UPS is generally not a home backup solution, rather it is a higher-end solution, with good products being pure sine wave with a static bypass switch and manual bypass switch. A UPS is the preferred backup solution for sensitive equipment like IT equipment, CCTV, servers, etc. Most UPS units are available with a long backup solution. When selecting the types of units that have a battery located externally, the higher the battery DC voltage the better, as it will result in smaller ampere-hour batteries for a specific standby backup. Also important is the available recharge amps of the rectifier, so don’t just buy the cheapest as you will not necessarily get the best solution nor value for money.


The solar industry has boomed in South Africa over the last decade, with many fly by night companies opening and closing every day. Everyone is now an ‘expert’ in solar and batteries and inverters.

There is one rule:

There is no cheap solar solution. Solar is the most expensive backup power solution available currently, even though the cost per watt has come down massively compared to 20 years ago.

The key problems with solar are:

  1. Capital outlay is very high versus power saving.
  2. After ten years you will need new panels.
  3. A big portion of the inverters used are very badly designed and highly unreliable, especially when it comes to power surges, while the ones that are good come with a huge price tag.
  4. Solar is definitely not a long-term solution as it has a design life; it doesn’t last forever.
  5. Roof space to fit panels is usually limited.
  6. Generally speaking, once it is installed and paid for, there is no after-sales service, no local technical support and no spare parts.
  1. The internet has a massive array of solar equipment for sale, but once you buy it, you’re on your own, technical support and repairs are often a problem.

Although at the moment people can benefit from reduced power reliance on ESKOM by installing solar, ESKOM is currently fighting for tariff changes, one of which is that solar users must pay at a higher tariff rate than others as, during peak power periods at night or on cloudy days, these users are drawing from the grid power and ESKOM has to cater for them in their power production planning. ESKOM cannot just up power production on any given day because it’s cloudy—they need to cater for this capacity all the time to be able to produce it when needed. So, the long-term outlook for solar users is that they will probably be paying much more for power than non-solar users in the future.

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