About the Solar Battery Calculator
A battery turns daytime solar into round-the-clock power.
This tool sizes the storage capacity you need for evening use and backup.
How this calculator works
We multiply the share of daily usage you want to cover by your days of autonomy, then adjust for usable depth of discharge.
Why it matters
- Avoid under- or over-sizing storage
- Plan for evening self-consumption
- Factor in backup needs
- Compare battery chemistries
Frequently asked questions
Most homes choose 10–15 kWh for evening use, more if they want multi-day backup.
The share of a battery you can safely use — modern LFP packs allow around 90%.