BrightGridChoosing a battery size is a balancing exercise. Too little storage may leave useful solar electricity unused, while excessive capacity can increase the installation cost without providing proportional additional value.
Start with electricity consumption
Review when electricity is consumed rather than looking only at annual usage. Evening and overnight demand is particularly relevant when considering solar self-consumption.
| Indicative capacity | Potential application |
|---|---|
| 5 kWh | Smaller evening loads |
| 8 kWh | Moderate household storage |
| 10 kWh | Higher evening and overnight demand |
| 15 kWh+ | Large electricity consumption |
Headline capacity versus usable capacity
Battery specifications can distinguish between total and usable capacity. The usable figure is more relevant when estimating how much electricity can actually be delivered.
Consider your electricity tariff
A time-of-use tariff can change the value of storage because the battery may be used to shift electricity between cheaper and more expensive periods.
Do not size a battery from solar panel count alone
Battery sizing should consider consumption, solar generation, tariff structure and the intended operating strategy.
Find your ideal battery size
Model your electricity use, solar generation and tariff before choosing battery capacity.
Check Your SavingsFrequently asked questions
Is a 10kWh battery enough for a house?
It may be suitable for some homes, but the correct size depends on electricity consumption, solar generation and the desired operating strategy.
Is a bigger solar battery better?
Not automatically. Additional capacity is only useful when the household can regularly make productive use of it.
Samuel Foster
Energy Storage Designer at BrightGrid Energy
