Find out what battery your home actually needs
Updated 14 January 2026
What Size Battery Do You Need?
| Your Evening Usage | Recommended Size | Backup Duration | Typical Home |
|---|---|---|---|
| Low evening usage (5-8 kWh) | 5-6 kWh | 4-6 hours essentials | Small household, mostly daytime use |
| Average evening usage (10-15 kWh) | 10 kWh | 8-10 hours essentials | Average family, some evening appliances |
| High evening usage (15-20 kWh) | 13-15 kWh | 12+ hours essentials | Large family, AC, pool pump |
| Very high / whole home backup | 20+ kWh | 24+ hours whole home | Large home, EV, complete independence |
Your ideal battery size is roughly equal to your daily solar export. Check your inverter app or ask your retailer for your average daily export figure.
Find out what battery your home actually needs
Free, takes 60 seconds, no obligation.
Over 3.6 million homes already claiming rebates
Buying Checklist
Common Mistakes to Avoid
warningBuying too large a battery
Problem: Spending extra money on capacity you wont use daily. Payback takes longer.
Solution:Match battery size to your evening usage and solar export, not maximum capacity available.
warningIgnoring power output (kW)
Problem: A large battery with low power output cant run high-draw appliances like air conditioning.
Solution:Check both capacity (kWh) AND power output (kW). Match power to your peak demand.
warningAssuming all batteries do backup
Problem: Many batteries require additional hardware for blackout backup, adding $500-$2,000.
Solution:If backup is important, confirm it is included and which circuits will be backed up.
warningNot checking inverter compatibility
Problem: Some batteries only work with specific inverters. May need expensive upgrades.
Solution:If adding to existing solar, confirm the battery works with your current inverter.
Battery installations are a bigger investment than panels alone, so installer stability matters even more. Over 200 solar companies have collapsed in Australia since 2010, and 1 in 6 solar homes now have no workmanship warranty. Before committing, check our collapsed solar companies tracker and make sure your installer has been trading for at least 5 years.
See what a battery would save you
Based on your usage and current tariff.
Over 3.6 million homes already claiming rebates
Questions to Ask Installers
Helpful Resources
The next step
If you have any questions about the information in this guide, feel free to get in touch:
Email: hello@whysolar.com.au
Tel: +61 2 5657 6527
If you're considering a home battery system, Bec and the team can help you get quotes from trusted, pre-vetted local installers:
Written by
Bec RamirezAussie Mum & Energy Expert
Helping families navigate the switch to solar with practical, real-world advice. Bec focuses on the financial side — rebates, bill savings, and financing options — so everyday Australians can see real value from going solar.
Learn more about Bec Ramirez