TL;DR

  • Backup power for load shedding starts with knowing your actual load, not buying the biggest inverter on the shelf.
  • Sequence matters: lights and fridge first, then Wi-Fi and geyser, then whole-home solar — never the reverse.
  • A modest inverter-battery setup covers most South African stages; you rarely need a noisy petrol generator.

What’s in this guide

Most of what you have read about backup power load shedding is trying to sell you something. The advice usually skips straight to a shopping list: this inverter, that battery, this generator. I have lived off-grid on a Karoo smallholding for over a decade, and I can tell you the shopping comes last, not first.

Backup power is not a personality trait or a status symbol. It is a trainable, calculable problem. Once you know your real load and your real priorities, the choices become obvious and often far cheaper than you feared.

The goal here is quiet competence: less fear, not more. Let us work through what you actually need, in the right order.

Backup power load shedding setup with inverter and lithium battery in a South African home
A modest inverter-battery system keeps the essentials running through most load-shedding stages.

What do you actually need for load shedding?

For most South African households, you need enough backup power to keep lights, a fridge, phone charging and Wi-Fi running for two to four hours at a time. That is a small, affordable system — not a whole-home solution.

Load shedding is scheduled and predictable. Eskom publishes stages, and apps like EskomSePush give you the times. This changes everything, because you are covering short, known gaps, not surviving an apocalypse.

The temptation is to over-build. I have watched neighbours spend R150,000 on systems they use for four hours a day. Start by asking a simpler question: what genuinely must stay on when the power drops?

  • Non-negotiable: a few LED lights, phone and laptop charging, Wi-Fi router.
  • Strongly wanted: fridge and freezer (to protect food), a fan or heater.
  • Nice to have: TV, geyser, borehole pump, kettle.

Get the first two tiers right and you have solved 90% of the problem for a fraction of the cost.

How do I calculate my backup power needs?

Add up the wattage of the appliances you want to run, then multiply by the hours you need them. That gives you watt-hours — the single most useful number in this whole exercise.

Here is the honest maths. Most appliances list their draw in watts on a label or plate. A rough worked example for a typical load-shedding block:

Appliance Power (W) Hours Watt-hours
LED lights (5) 50 4 200
Wi-Fi router 15 4 60
Fridge/freezer 150 (avg) 4 600
Laptop + phone 90 4 360
TV 80 2 160
Total ~1,380 Wh

So a battery of roughly 1.5–2 kWh usable capacity comfortably covers this household through a typical stage. Note the word usable: lithium (LiFePO4) batteries give you most of their rated capacity, while lead-acid batteries should only be discharged to about 50%, so you need twice the nameplate size.

You also need an inverter rated for your peak draw — the highest wattage running at once. Kettles, geysers and pool pumps spike hard, which is exactly why we leave them off the list. For the load above, a 1,500–2,000W inverter is plenty.

Inverter, generator or solar: which is right?

For scheduled load shedding, an inverter-battery system is the quiet, low-maintenance winner for most homes. Generators suit occasional heavy loads, and solar makes sense once you want to reduce your bill, not just survive outages.

Each option solves a different problem. Match the tool to your actual situation rather than the marketing.

Option Best for Rough cost (ZAR) Downsides
Inverter + battery Silent, automatic backup for essentials R8,000–R45,000 Limited runtime without solar top-up
Petrol/diesel generator Heavy loads, long rural outages R4,000–R30,000 Noise, fumes, fuel storage, manual start
Solar + inverter + battery Cutting bills and outages together R60,000–R200,000+ High upfront cost; needs roof and sun
Portable power station Renters, small flats, minimal needs R5,000–R25,000 Smaller capacity; slower recharge

I ran a small generator in my first year off-grid. It worked, but the fuel runs, the noise and the maintenance wore thin fast. A generator is a good tool for a rural smallholding with long outages and a borehole to pump, not for a suburban home riding out Stage 4.

If you are weighing solar seriously, read my guide to off-grid solar basics before you commit — sizing a solar array well is a different discipline.

How should I sequence my backup power upgrades?

Buy in stages, cheapest and most essential first. A small inverter for lights and Wi-Fi comes before a fridge backup, which comes before solar panels, which comes before whole-home coverage.

This is the principle I return to again and again: sequencing beats shopping lists. You never have to spend everything at once, and each stage delivers real comfort.

Solar panels on a South African smallholding roof providing daytime charging for battery backup
Solar comes later in the sequence — after you have covered your essential loads with a battery.
  1. Stage 1 — Essentials (R5,000–R12,000): A small inverter or power station for lights, phones and Wi-Fi. This alone removes most of the daily irritation.
  2. Stage 2 — Fridge protection (R15,000–R30,000): A larger inverter and battery to keep your fridge and freezer cold, protecting your food store.
  3. Stage 3 — Solar charging (R30,000+): Panels to recharge your battery during the day, so back-to-back outages stop draining you.
  4. Stage 4 — Whole home (R100,000+): Full solar and larger battery bank if you want to run heavy loads and cut your Eskom bill.

Most people never need to reach Stage 4. And notice what comes first: water security and food storage should already be handled before you spend big here. A battery is no comfort if your borehole pump has no plan. See my notes on water storage and JoJo tanks for that groundwork.

What does backup power really cost to run?

An inverter-battery system costs almost nothing to run once installed, since you recharge from the grid or solar. A generator costs real money every hour it runs — mostly in fuel.

Let us be concrete. A 3kVA generator burns roughly 1–1.5 litres of petrol per hour under moderate load. At around R23/litre, that is R23–R35 per hour. Four hours a day across a month of load shedding runs into thousands of rand — before oil changes and servicing.

An inverter recharging from the grid uses cheap off-peak power; from solar it is free. This is why the quiet inverter usually wins on total cost of ownership, even when the generator is cheaper to buy.

Lithium batteries also last longer. According to the US Department of Energy, modern battery storage is rated for many thousands of cycles, and LiFePO4 chemistry in particular tolerates daily deep cycling far better than old lead-acid banks. Over ten years, that longevity often justifies the higher sticker price.

Common mistakes to avoid

The most common backup power load shedding mistake is buying kit before doing the maths. The second is prioritising luxury loads over the essentials that actually matter.

I see the same errors repeatedly, and they are all avoidable:

  • Trying to run the geyser or kettle off backup. These are enormous loads. Use gas or off-peak heating instead.
  • Undersizing the inverter for peak draw. Your fridge’s start-up surge can be three times its running watts.
  • DIY wiring into the mains. Anything tied into your distribution board needs a registered electrician and a Certificate of Compliance. This is a safety and insurance issue, not red tape.
  • Ignoring registration. Grid-tied solar systems must be registered with your municipality; check the NERSA and local municipal rules.
  • Buying cheap lead-acid to save money. The lower cycle life often makes it more expensive over time.

None of this is complicated once you slow down. Do the calculation, respect the essentials, and get a professional to sign off anything touching your wiring.

Key takeaways

  1. Calculate your watt-hours before you buy anything — it is the number that decides everything.
  2. Cover essentials first: lights, Wi-Fi, phone charging, then the fridge.
  3. An inverter-battery system suits most homes better than a noisy, fuel-hungry generator.
  4. Sequence your upgrades in affordable stages; you rarely need whole-home coverage.
  5. Handle water and food storage before you invest heavily in power.
  6. Get a registered electrician for any mains wiring and register grid-tied solar.

Frequently asked questions

What is the cheapest backup power for load shedding?

The cheapest effective backup power load shedding option is a small inverter or portable power station running lights, Wi-Fi and phone charging, from around R5,000. It will not power your fridge or heavy appliances, but it removes the daily disruption of scheduled outages at a fraction of the cost of a full solar system.

How big an inverter do I need for load shedding?

Size the inverter to your peak simultaneous draw, not your total watt-hours. For lights, Wi-Fi, a fridge and device charging, a 1,500–2,000W inverter is usually ample. Only step up to 3,000W or more if you plan to run larger appliances at the same time, which is rarely worthwhile.

Is an inverter better than a generator?

For scheduled load shedding, yes. Inverters are silent, automatic, need no fuel and cost little to run. Generators only make sense for very long rural outages or heavy loads like borehole pumps. If you live in a suburb riding out a few hours of Stage 4, an inverter-battery system will serve you far better.

Can I run my fridge on backup power?

Yes, comfortably. A fridge draws around 100–200W while running but surges higher on start-up, so choose an inverter rated for that peak. A 1.5–2 kWh battery keeps a fridge and a few lights going through a typical load-shedding block, protecting your food store without a large or expensive system.

Do I need to register my backup power system?

Battery-and-inverter systems that are not tied into the grid generally need a Certificate of Compliance if wired into your board, done by a registered electrician. Grid-tied solar systems must be registered with your municipality. Check your local rules and NERSA guidance before installation to stay compliant and keep your insurance valid.

Ready to build your plan the calm, sequenced way? Start with the foundations in my home preparedness checklist, then size your system with confidence — no panic buying required.

— Lisa, off-grid homesteader and writer at Survival and Prepping. Ten-plus years living with solar, boreholes and the quiet competence that comes from doing the maths first.