How Long Can I Run My Geyser on an Inverter During Load Shedding? (2026)
23 June 2026 · Plumbers On Duty Editorial
Honest answer first
Don't. A standard 3kW geyser element will drain a 5kWh battery in 1 hour 40 minutes and won't reheat in that time. With load shedding largely behind us in 2026 but still flaring up regionally, the maths still doesn't work for most homes.
The numbers
- Standard SA geyser element: 3,000W (3kW)
- Time to heat 150L from 20°C to 60°C: ~2 hours
- Energy used per heating cycle: ~6 kWh
- Typical home inverter battery: 5-10 kWh
A 5kWh battery + 5kW inverter combo gives you ONE partial heat-up before the battery dies and your house also has no lights.
What actually works in 2026
Option 1: Geyser timer (R450-R900) – Heats only during off-peak / solar hours. Cuts your geyser bill by 35-50% even without load shedding.
Option 2: Geyser blanket + pipe insulation (R600 total) – Cuts standing losses by 40%. The hot water lasts through an evening outage.
Option 3: 2kW element swap (R380 part) – Halves the inverter draw. Heats slower but works with a 3kW inverter.
Option 4: Solar geyser conversion (R28k-R42k) – Fully off-grid hot water. Pays back in 5-7 years even at 2026 Eskom tariffs.
Option 5: Heat pump (R32k-R48k) – Uses only 800W. Runs comfortably on a 3kW inverter.
What people get wrong
Connecting the geyser to an inverter circuit without an essential-loads contactor will cook the inverter on the first cycle. Always have an electrician install a proper solar geyser or heat pump if you're going off-grid.