Ask Our Energy Experts 💬

The inverter size (5kW) tells you how much power it can deliver at once — but runtime depends entirely on your battery capacity, not the inverter rating.

A standard South African fridge draws between 100W and 200W while the compressor runs, but the compressor only runs about 30–40% of the time. So your effective average consumption is around 50–80W per hour.

If you're running other loads alongside the fridge (router, lights, TV), subtract those watts from your available capacity. A typical Stage 4 outage is 4.5 hours — a modest 24V 100Ah system handles that easily for just a fridge.

Absolutely — you just need to think about portable and plug-in solar options rather than a fixed rooftop installation.

Best options for renters:

• Portable power stations (like the EcoFlow RIVER or Bluetti AC200P) — these are all-in-one battery + inverter units you take with you when you move. Cost: R8,000–R25,000
• Plug-in solar panels — 200W–400W panels that connect directly to your power station. No permanent installation needed.
• Desktop UPS — keeps your router and laptop alive during 2-4 hour outages. Cost: R1,500–R4,000

If your landlord is open to it, you could also propose a shared-cost rooftop installation — some landlords agree because it adds property value and they can market it as "solar-ready". Get any agreement in writing.

The payback period for a portable setup is roughly 2–3 years based on eliminating UPS battery replacements and reducing generator use.

Sizing a generator wrong is one of the most common mistakes South Africans make — too small and it trips under load, too large and you waste fuel at idle. Here's how to get it right.

Step 1: List every appliance you want to run during load shedding and find the wattage (usually on a sticker on the back).

Step 2: Add them up. This is your running load.

Step 3: Multiply by 1.25–1.5 to account for startup surge — motors (fridge, washing machine, pool pump) draw 3–6x their running wattage for a fraction of a second when they start.

Petrol vs Diesel: Petrol generators are cheaper to buy but more expensive to run. For outages under 2 hours, petrol is fine. For longer or frequent use, diesel pays off within 6–12 months.

Usually yes — but there are important rules to follow or you risk damaging your existing batteries and potentially your inverter.

The golden rules of battery expansion:

• Same voltage: All batteries in the bank must be the same voltage (12V, 24V, or 48V)
• Same chemistry: Never mix lead-acid with lithium — they charge at different voltages and will damage each other
• Same brand and age: Strongly recommended — a new battery paired with an old one will cause the new one to age prematurely
• Same capacity (Ah): Mismatched capacities cause uneven charging and accelerated degradation

If your existing batteries are more than 2 years old, replacing the whole bank with new batteries is usually better value than adding to it. An old weak cell drags down the whole bank.

Also check your inverter's maximum battery bank capacity — most residential inverters specify a maximum Ah rating in the manual. Exceeding this can damage the charger circuitry.

This is one of the most misunderstood aspects of solar in South Africa — what happens depends entirely on which type of solar system you have.

Grid-tied (no battery): Your system automatically shuts down during load shedding. This is not a fault — it's a legal safety requirement called anti-islanding protection. If your inverter kept feeding power into the grid during an outage, it could electrocute Eskom workers repairing the lines.

Hybrid (with battery): When load shedding starts, your inverter detects the grid going down and switches to battery power within milliseconds — usually too fast for your TV or computers to even notice. Your solar panels continue charging the batteries during the day. This is the most popular setup for South African homeowners.

Off-grid: Completely unaffected by load shedding. Your system operates independently of Eskom at all times. However, it requires a larger battery bank to cover nights and cloudy days.

For load shedding resilience, a hybrid system is the sweet spot — lower cost than off-grid while still giving you full backup power.

Battery lifespan varies significantly depending on chemistry, how deeply you discharge, and temperature — South Africa's climate can actually accelerate degradation.

Signs your battery needs replacing:

• Runtime has dropped to less than 50% of what it used to be
• Battery feels warm even when not charging
• Inverter shows "battery low" much sooner than it used to
• Swollen or bulging battery casing (replace immediately)
• Rotten egg smell (hydrogen gas — ventilate immediately)

Both are excellent alternatives to a standard electric geyser, but they work very differently and suit different households.

Recommendation by situation:

• Gauteng, inland high altitude: Solar geyser performs very well — high sun hours year-round
• Cape Town / coastal: Heat pump may edge it out in winter months
• On-grid with solar panels: Heat pump pairs beautifully — run it during peak solar production
• Budget-conscious: Solar geyser is cheaper upfront and has fewer moving parts to fail

Both will reduce your geyser electricity cost by 60–80%. You can't go wrong with either — it comes down to your specific situation and budget.

Most inverters have a display or app that shows you exactly what's happening in real time. Here's what to check and what the numbers should look like on a clear day.

What to look at on your inverter display:

• PV voltage / PV power: Should be generating during daylight hours. A 5kW system should produce 3–5kW on a clear midday
• Battery State of Charge (SoC): Should be climbing in the morning and reach 90–100% by midday on a sunny day
• Output power: Should match what you're consuming in the house
• Grid status: Connected or disconnected — check this matches reality

Daily kWh benchmarks for South Africa (5kW system):

• Johannesburg, summer: 20–25 kWh/day
• Johannesburg, winter: 15–18 kWh/day
• Cape Town, summer: 22–28 kWh/day
• Cape Town, winter: 10–14 kWh/day

Common problems to look for:

• Production drops after 10am — check for shading from a new tree or structure
• One string producing significantly less — could be a faulty panel or connection
• System not starting in the morning — check for fault codes on the display
• Dirty panels — a 20% dust layer can reduce output by 15–20%