California solar interconnection
One tariff frame, three utilities, three sets of forms. How Rule 21 works across the California investor-owned utilities covered by SunDocket's requirements wiki.
The Rule 21 frame
California interconnection for behind-the-meter solar and storage runs under Electric Rule 21 — the interconnection tariff the California Public Utilities Commission requires of its jurisdictional utilities. Rule 21 governs how generating facilities connect in parallel with the distribution system: the screening ladder (Initial Review → Supplemental Review → Detailed Study), the business-day review clocks, and the fee framework.
The structural point that trips up multi-utility installers: Rule 21 is not one document. PG&E, SCE, and SDG&E each file their own version of the tariff, and each runs its own portal, its own forms, and its own fee schedule on top of the shared frame. Knowing Rule 21 at one utility gets you the shape of the process everywhere; it does not get you the packet.
Utilities covered
PG&E
Northern & central California
The Your Projects portal, NEM-class and Rule 21 export pathways, published review clocks, and the fee table.
SCE
Southern California
Two portals split by program — the PowerClerk-based Online Interconnection Application System and GIPT — plus Fast Track clocks and sizing attestations.
SDG&E
San Diego area
The DIIS portal, the Fast Track meter-photo requirement, invoiced fees, and published processing averages.
What's shared vs utility-specific
| Shared across all three IOUs | Utility-specific |
|---|---|
| The Rule 21 screening ladder: Initial Review screens → Supplemental Review → Detailed Study | Each IOU files its own Rule 21 tariff — clocks and fee tables live in the utility's own filing |
| The Solar Billing Plan as the NEM successor for systems applied for after April 2023 | Portals: PG&E's Your Projects, SCE's Online Interconnection Application System and GIPT, SDG&E's DIIS |
| CEC certified equipment lists; UL 1741 SB / Smart Inverter compliance per CPUC directive | Form numbers and revisions — every packet form is a utility form, checked against that utility's tariff book |
| Single-line diagram, storage charging-source and export-mode declarations, certified power control system documentation for limited/non-export designs | Fee amounts and how they're collected (paid at submission vs invoiced), plus utility-specific items like SDG&E's meter-and-placard photo |
| CSLB contractor licensing and California Solar Consumer Protection Guide disclosures for residential sales | Detailed-study structures (e.g., Independent Study Process vs Distribution Group Study windows) and program deadlines |
The practical consequence: a deficiency-free packet at one California IOU can still bounce at another over a form revision, a portal split, or a fee handled differently. The per-utility pages above carry those specifics with sources cited and dated.
Solar Billing Plan context
The Solar Billing Plan is California's implementation of the Net Billing Tariff — the successor to Net Energy Metering 2.0 at all three IOUs. It applies to eligible renewable systems applied for after NEM 2.0 closed to new applications in April 2023, and compensates exported energy at hourly export prices rather than retail-rate netting. Legacy NEM 2.0 projects ran against final-documentation deadlines in 2026 (SCE published April 14, 2026, with February 14, 2027 for Virtual NEM and NEM-Aggregation; PG&E's NEM2 completion deadline was April 15, 2026) — projects that missed them proceed under the Solar Billing Plan.
For interconnection purposes, the program determines which pathway, portal, and fee apply — so confirming the program is step zero of a California packet.
Filing in California every month?
Design partners get 5 free filings and their territory encoded first — packets produced with dual human review while the software is built.
Related pages
- Interconnection fees by utility — the published fee structures side by side, with verify flags on every revision-sensitive amount.
- Rule 21 vs the NY SIR — how California's utility-filed tariff compares with New York's statewide standard, for installers working both coasts.
- Interconnection glossary — Rule 21, the Solar Billing Plan, power control systems, certified equipment lists, and the rest of the vocabulary, defined.