Do you actually need a battery?
A battery earns its price when your home uses a lot of power after sunset. It stores midday solar for the evening and lifts the share of generation you use yourself from about 65% to about 85% in the SolRand model. At an added R40,000 to R80,000, a home that is busy all day and quiet at night often pays back faster on panels alone.
When you use power matters more than how much
Two homes can both use 750 kWh a month and need opposite systems. A home office running 8am to 5pm eats solar as it is made. A family out all day, cooking from 6pm, exports cheap midday power and buys back evening power unless a battery bridges the gap.
Share of your own solar you actually use
Model defaults. Your evening load decides where you land.
Sizing, in plain numbers
| Evening load | Battery that fits | What it covers |
|---|---|---|
| Lights, TV, Wi-Fi, fridge | 5 kWh | An evening of essentials, with care |
| The above, plus cooking in rotation | 10 kWh | A fuller evening, still not everything at once |
| Geyser, oven and aircon together | More than 10 kWh, or load control | A battery alone is the expensive way to do this |
The geyser problem
A 3 kW geyser element drains a 5 kWh battery fast. A timer that heats water at midday from solar, or a dedicated solar geyser, usually beats buying a bigger battery for hot water. Ask the installer to cost both and show you both numbers.
A workable order of decisions
- Shift loads into daylight first. Timers cost hundreds, not tens of thousands.
- Size panels for daytime use plus battery charging.
- Add the smallest battery that covers your real evening list.
Questions people actually ask
Can I add a battery later?
Usually yes, if the inverter is a hybrid model with battery headroom. Get that confirmed in writing. A grid-tied-only inverter can make a later battery costly.
How long does a home battery last?
Lithium home batteries are commonly warranted for about 10 years or a set cycle count. The 25-year figures on this site do not assume one battery lasts 25 years. Treat replacement as a real future expense.