Define critical loads before capacity
A backup storage system should be sized from the supported load list rather than the total site load. Separate critical lighting, servers, controls, security, refrigeration, pumps, production equipment, or emergency circuits from non-critical loads.
- List each critical load, rated power, startup current, and required backup duration.
- Confirm whether the battery must support black start, UPS-like transfer, or longer-duration backup.
- Review local electrical code, transfer equipment, protection coordination, and grid interconnection rules.
Reserve strategy and daily operation
If the same battery is also used for peak shaving or solar self-consumption, the EMS must reserve enough state of charge for backup. This reserve reduces the energy available for daily economic dispatch unless the system is sized for both functions.
