Battery Storage Sizing Compared
Two storage systems with the same headline capacity can be sized for completely different reasons, which is why sizing comparisons should compare the reasoning, not just the rating. There are three common ways a storage size gets decided, and most real projects blend them.
| Sizing approach | Starts from | Suits |
|---|---|---|
| Load-led | The loads that must be supplied, and for how long | Backup planning for homes and essential industrial loads |
| Solar-led | The surplus the array produces on a typical day | Self-consumption projects that want to keep solar energy on site |
| Tariff-led | The gap between peak and off-peak prices and the site's demand peaks | Industrial peak shaving with a cabinet system |
For a home, the load-led and solar-led views usually meet: the battery should be large enough to carry the evening loads, and not so large that the array can rarely fill it. For a factory, the tariff-led view often dominates, because a cabinet that discharges into a short daily peak can be smaller — and cheaper — than one sized to carry the whole site. The sizing guide turns these approaches into a worksheet of questions, and the two documented product families show the formats the answers point to.
Avoid the two common sizing mistakes: copying a neighbour's system without comparing load profiles, and sizing for the single worst day of the year rather than the pattern of a typical month. Storage earns its keep on ordinary days.