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Battery storage design for solar permit sets
In short
Adding a battery to a solar permit set means showing where the energy storage system goes, how far it sits from doors, windows and other units, the clearances and ventilation around it, and how it ties into the electrical system and backup loads. We add it as its own sheet for $75 on a standard plan set, drawn to NFPA 855 and the residential and fire codes your jurisdiction adopted.
Location and capacity limits on this page are from the 2021 International Residential Code, section R328, which follows NFPA 855. Earlier editions differ and many jurisdictions amend them — confirm the adopted edition before relying on any figure.
What the battery sheet shows
- Battery location and mounting, dimensioned.
- Separation from doors, windows and other storage units.
- Working clearances and ventilation.
- Impact protection where the unit is exposed to vehicles, such as in a garage.
- Smart-inverter configuration and the backup-load panel, coordinated with the three-line diagram.
- Storage-specific signage, added to the label schedule.
Where a residential battery can go
Under the 2021 IRC, energy storage systems are permitted in garages, detached accessory structures, utility closets, basements and storage or utility spaces, and outdoors or on exterior walls. They are not permitted in sleeping rooms, in closets opening into them, or in habitable space. An attached garage qualifies only where it’s separated from the living space, and a unit on an exterior wall must sit at least 3 feet from doors and windows that open into the home.
How much storage, and where
| Location | Aggregate limit |
|---|---|
| Utility closets, basements, storage or utility spaces | 40 kWh |
| Attached or detached garages, detached accessory structures | 80 kWh |
| Exterior walls | 80 kWh |
| Outdoors on the ground | 80 kWh |
Individual units are limited to 20 kWh, and units are spaced 3 feet apart unless large-scale fire testing to UL 9540A supports a closer arrangement. Many current products are documented for closer spacing, which is one reason the manufacturer’s documentation belongs in the set.
Why it’s a separate sheet
A battery brings requirements a solar-only set doesn’t have: location limits, separation, impact protection, ventilation, backup-load wiring and extra signage. Drawing it as its own sheet puts all of that where the reviewer expects to find it.