Which Appliances Should Your Backup Power Run During Load-Shedding?

First, understand watts vs watt-hours

Two numbers decide everything. Watts (W) is how much power an appliance draws at any instant — it tells you whether your inverter can even switch the thing on. Watt-hours (Wh) is watts multiplied by time — it tells you how much of your battery the appliance eats over an evening.

A phone charger draws maybe 10W. Leave it on for two hours and it's used 20Wh — nothing. A 2,000W kettle draws two hundred times as much and is often on when other things are too. Even though it only runs for a few minutes, it hammers your inverter's instant capacity. This is why "how many appliances" is the wrong question. It's about which appliances, and whether they make heat.

The green list: run these without a second thought

These are low-draw, and together they cover most of what makes a home livable during an outage.

• LED lights — a few watts each. A whole home lit costs less than a single kettle.
• Wi-Fi router and fibre ONT — around 10-20W combined. Keeping these on means you stay connected, can work, and can keep the kids occupied.
• TV and decoder — a modern LED TV is roughly 50-150W. An evening of viewing is comfortably within reach.
• Laptops and phone chargers — laptops sip 40-90W; phones almost nothing.
• Fridge and freezer — this surprises people, but a modern fridge only draws around 100-200W and cycles on and off, so its average draw is modest. Keeping it cold protects hundreds of rands of food.
• Wi-Fi, alarm, electric gate and CCTV — these low-draw security and connectivity loads are exactly what you want backed up. We cover them in depth in our security guide.

Add all of that up and a typical family's genuine essentials often sit well under 1kW of continuous draw — squarely in the range a well-chosen home system handles with ease.

The red list: think twice before backing these up

These appliances share a trait — they turn electricity into heat, or they run big motors. Both are brutal on batteries.

• Kettle — around 2,000W. It'll run on a bigger inverter, but boiling a full kettle repeatedly drains a small battery fast.
• Geyser — 2,000-3,000W and often on for long stretches. Backing up a standard geyser is one of the fastest ways to flatten a battery. A timer, a geyser blanket, or a heat-pump upgrade is usually smarter than backing it up.
• Oven and stove plates — 2,000W and up per element. Cook with gas during load-shedding and save your battery for the essentials.
• Electric heaters — 1,000-2,000W of pure heat. In winter these can single-handedly undo a whole system's runtime. A gas heater or an electric blanket (which sips power) is far kinder.
• Tumble dryer, dishwasher, washing machine — high draw and long cycles. Easy to simply run when the grid is up.
• Hair dryer, iron, air fryer, microwave — short bursts, but very high instantaneous draw. Manageable on a larger system, but each one eats into your reserve.

The rule of thumb: if it makes heat, be careful. A single geyser or heater can demand more power than every light, screen and fridge in your house combined.

10LED lights (whole home)

20Wi-Fi + fibre ONT

100TV + decoder

150Fridge (average draw)

2000Kettle

3000 | unit=W | caption=Typical power draw — heat-makers dwarf the essentialsGeyser

How this translates into a system size

Once you know your essentials, sizing becomes common sense. You're answering two questions: can the inverter handle my peak draw? and does the battery hold enough to cover the longest outage?

For a home keeping lights, Wi-Fi, a TV, chargers and a fridge running, an entry-level system does the job. Alumo's Bronze "Watt-a-Deal" — a 3.6kW Sunsynk inverter with a 3.6kWh battery — comfortably carries those essentials through a typical outage window.

If you also want the occasional microwave or air-fryer burst, or you're running a busier household with more screens and a bigger fridge-freezer, step up. The Silver "The Eishkom Ex" adds a little more headroom and is the popular middle choice. And if you want to cook, run heavier appliances or bridge back-to-back Stage 6 slots without thinking about it, the Gold "The Power Bae" with its 5kW inverter and larger battery gives you real breathing room.

The point is that you don't pay for a whole-house system when your real need is a well-run essentials list — and you don't cripple yourself with something too small either.

A five-minute exercise for your own home

Walk through your house and jot down what you genuinely can't do without during an outage: the lights in the rooms you use, the router, the TV, the fridge, chargers, and your security kit. Ignore anything that makes heat unless you're specifically choosing to back it up. Add up the watts. That number — not the size of your house or your neighbour's system — is what should drive your decision.

When you're ready, the fastest way to get it right is a professional load assessment. Get a free quote → and a specialist will size a system around your actual essentials, so you're not paying for power you'll never use.

Frequently asked questions

Can I run my kettle or geyser on backup power?

You can, on a larger system, but you probably shouldn't want to. Kettles and geysers are heat-producing appliances that draw enormous power and flatten batteries quickly. Most households find it far cheaper to boil water on gas and use a geyser timer or blanket, keeping the battery for lights, Wi-Fi and the fridge.

Will a small inverter run my fridge?

Usually yes. A modern fridge only draws around 100-200W on average and cycles on and off, so it's a low-draw essential. The thing to check is the start-up surge when the compressor kicks in — a quality inverter is designed to handle it, which is another reason a proper system beats a bargain-bin unit.

How do I work out what size system I need?

List the appliances you truly need during an outage, add up their watts to check your inverter can handle the peak, then multiply by the hours you want to run them to estimate battery size. It's easier to have a specialist do a proper load assessment, which is included when you request a free quote.

Why does my inverter trip when I switch on certain appliances?

It's hitting the inverter's instantaneous power limit. Heat-making appliances like kettles, irons and heaters, plus motor-driven ones, demand a big burst of watts the moment they switch on. If that burst exceeds the inverter's rating, it trips to protect itself — a sign the system is undersized for that appliance.

Is SolarGuide the installer?

No. SolarGuide is an independent referral partner. Alumo supplies, installs, finances and warrants the systems. We help you compare options and get a free quote. All pricing is indicative and subject to a site assessment and credit approval.