Battery Storage Sizing Guide
Storage sizing looks like a calculation, but it starts as a set of questions. Suppliers who size responsibly will ask them anyway; arriving with the answers shortens the conversation and improves the result. This guide gives the questions and explains what each one decides.
The sizing questions
| Question | What it decides |
|---|---|
| Which loads must the storage supply? | The power the system must deliver at one time |
| For how long must it supply them? | The energy the system must hold |
| How much surplus does the solar array produce on a typical day? | How much energy is available to store on site |
| What is the leading duty: self-consumption, peak shaving or backup? | Which of the first three answers gets priority when they conflict |
| How often will the system cycle: daily, weekly, or mainly on standby? | The cycle duty the battery must be documented for |
Answer with the pattern of a typical month, not the extreme day. A system sized for the worst day of the year spends the other days oversized and underused, while a system sized for the typical pattern and honest about its limits performs every day. Where a figure is an estimate, mark it as one — a good sizing conversation can work with estimates, but not with estimates dressed as measurements.
The sizing comparison page shows the three sizing approaches side by side; the confirmation page then turns your answers into an enquiry. Detailed capacity figures belong on the product pages, where they are stated for a specific model — sizing here is about your site, not about a catalogue number.