BrightGridChoosing a solar battery is a balancing exercise. A battery that is too small may leave useful solar generation unused, while a battery that is too large can increase the upfront cost without delivering proportional value.
Start with electricity consumption
Review how much electricity the property uses during the evening and overnight. This provides a better starting point than selecting a battery purely from the solar panel size.
Consider solar generation
The battery needs sufficient solar generation to charge regularly. A very large battery may remain partially charged for long periods if the solar system cannot consistently provide enough surplus energy.
Common home battery sizes
| Battery size | Typical application |
|---|---|
| 5 kWh | Smaller homes and lower evening demand |
| 7–8 kWh | Moderate household demand |
| 10 kWh | Common larger domestic applications |
| 15 kWh+ | High electricity demand or larger energy systems |
What if you have an EV?
An EV creates a large electricity load, but it does not automatically mean that a very large home battery is required. Direct solar charging and tariff-based EV charging may provide better flexibility.
Tariffs also affect battery sizing
If the battery will be charged from the grid during cheaper periods, the required operating strategy may differ from a solar-only battery system.
Usable capacity matters
Compare usable battery capacity and operating limits rather than relying only on the headline battery capacity.
Find your ideal battery size
Model your electricity use, solar generation and tariff before selecting battery capacity.
Calculate Battery SizeFrequently asked questions
Is a 10 kWh battery enough for a house?
It may be suitable for many homes, but the correct size depends on electricity consumption, solar generation, tariffs and operating strategy.
Is a bigger solar battery better?
Not necessarily. Oversizing can increase cost without producing proportional additional savings.
How do I calculate battery size?
Start with evening and overnight electricity demand, then compare it with available solar generation and the intended tariff strategy.
Does an EV mean I need a bigger battery?
Not automatically. EV charging can be managed directly from solar or through suitable electricity tariffs.
Natalie Brooks
Energy Storage Designer at BrightGrid Energy
