If you already have solar in Southern California Edison (SCE) territory and want to add a battery later, do not treat the project as only a hardware purchase. The decision has at least two separate approval tracks:

1. the city/county/AHJ permit and inspection path; and
2. the SCE interconnection path.

The exact requirements depend on the existing system, tariff, battery/inverter configuration, and what is changing at the point of interconnection.

Does SCE need to know about the battery?

SCE’s current solar FAQ states that when an energy-storage device is paired with an eligible generating system, an Interconnection Application is required. It also publishes separate rules for modifications and expansions to existing generating facilities. See SCE Solar FAQ.

For existing NEM 1.0/2.0 systems, SCE says qualifying expansions can remain under the existing program within specified limits, but a revised application with the new configuration is still required. SCE also states that the capacity limits described in that FAQ apply when adding energy storage to an existing solar installation.

Do not infer your tariff outcome from a forum comment. Ask SCE which application type applies to the specific existing account and proposed storage configuration.

Is the SCE application the same as the city permit?

No. SCE interconnection approval does not replace local building/electrical permitting.

Your AHJ may require a permit and inspection for the battery, associated electrical work, equipment relocation, panel work, or other scope. SCE itself notes that cities/AHJs can have their own requirements for certain interconnection methods and tells customers/contractors to determine whether the AHJ accepts the proposed method. See the same SCE Solar FAQ.

What if the equipment or output changes?

SCE’s Solar Billing Plan FAQ says some system modifications require notification, and distinguishes certain qualified changes from changes that require a new interconnection application or approval. It also states that any change to the point of interconnection requires a new application. See SCE Solar Billing Plan FAQs.

That means “I’m only adding a battery” is not enough information to determine the path.

Questions to answer before choosing the battery

Before buying equipment, capture:

• your current SCE tariff/program and existing PTO status;
• existing PV DC size and inverter AC rating;
• existing battery/storage, if any;
• proposed battery model and inverter architecture;
• whether the point of interconnection changes;
• whether an MPU, main-breaker change, GMA change, or load relocation is involved;
• AHJ/city/county;
• whether the AHJ requires a separate storage/electrical permit;
• which SCE application or modification path applies;
• whether a new PTO is required before the added equipment may operate as proposed.

The practical rule

Choose the battery after you know the approval path, not before.

Two batteries with similar consumer features can produce different permitting/interconnection work if they use different inverter architecture, change the interconnection configuration, require panel work, or affect the approved system output.

GridPermit is an educational permitting/interconnection guide, not SCE or the local AHJ. Confirm the live requirements for the existing account and proposed equipment with SCE and the permitting authority before installation or energization.