SDG&E interconnection requirements
Sample preview — compiled from public sources 2026-08-19
Who this applies to
This page covers behind-the-meter generating facilities — solar, storage, and solar-plus-storage — interconnecting in parallel with San Diego Gas & Electric's distribution system under Electric Rule 21, the interconnection tariff that the California Public Utilities Commission requires of its jurisdictional utilities (PG&E, SCE, and SDG&E each file their own version — this page describes SDG&E's filing and processes only).
- Residential and small commercial solar — filed under SDG&E's net-metering successor program, the Solar Billing Plan (California's Net Billing Tariff), through the DIIS online portal.
- Storage — stand-alone and paired storage interconnect through the same portal; charging source and export mode shape the review.
- Non-export projects — generation for on-site use only, filed under Rule 21 with non-export documentation.
- Larger export projects — Rule 21 interconnection for exporting generators selling to SDG&E outside the retail billing programs, including RES-BCT (a service-wide capacity cap of 20.25 MW applies, first-come first-served).
Wholesale projects under SDG&E's Wholesale Distribution Access Tariff (WDAT) and CAISO transmission-level interconnections are out of scope for this page.
Application pathway overview
Behind-the-meter applications go through SDG&E's Distribution Interconnection Information System (DIIS), the online portal that takes the application data, document uploads, and status tracking; SDG&E's Customer Generation team invoices the applicable fee. Rule 21 requests can also be filed on SDG&E's published application forms where the portal pathway doesn't apply.
Rule 21 review is a screening ladder. Complete applications are screened; projects that pass interconnect without further study. Failing specific screens moves a project toward Supplemental Review and then detailed study — SDG&E's Independent Study Process (for projects passing Screen Q but failing Screen R) or a Distribution Group Study submitted during designated application windows. Detailed study is slower, carries additional fees, and can identify distribution upgrades.
| Pathway | Typical projects | Review |
|---|---|---|
| Solar Billing Plan / NEM-class interconnection (via DIIS) | Residential and small commercial solar, solar-plus-storage, stand-alone storage | Streamlined screening; SDG&E publishes average processing under five business days for complete online applications |
| Rule 21 interconnection request (Form 142-05203 confirm current revision) | Exporting and non-exporting generators outside the retail billing programs | Screening → Supplemental Review → Independent Study Process or Distribution Group Study as screens require |
| Pre-application report (Form 142-05204 confirm current revision) | Optional; larger projects scoping a site before applying | Data report only — not an application |
Required forms & documents
The structural contents of an SDG&E behind-the-meter packet. Exact forms depend on program and configuration; every form number below should be checked against SDG&E's current tariff book before filing.
- Interconnection application in the DIIS portal, tied to the correct customer of record and service account
- Rule 21 interconnection request form where applicable (Form 142-05203 confirm current revision)
- Signed Customer Generation / interconnection agreement for the program (Form 142-0541 confirm current revision)
- Electrical one-line (single-line) diagram showing point of interconnection, disconnects, overcurrent protection, and grounding
- Site photo requirement for Fast Track-eligible projects: a photo showing the SDG&E meter and the caution placard on the service panel
- Equipment spec sheets — CEC-listed modules, inverters, and storage
- Storage operating details: charging source (grid vs. PV-only), export mode, and certified power control system documentation for limited- or non-export designs
- Contractor license (CSLB) information
- California Solar Consumer Protection Guide disclosures for residential sales
- Application fee payment per SDG&E's invoice for the program
Fees
SDG&E charges a flat fee that varies by program: a small one-time interconnection fee for NEM-class systems of 1 MW or less, and a larger non-refundable Interconnection Request Fee for Rule 21 generator applications, invoiced after submission. Projects pushed into Supplemental Review or detailed study pay additional study fees, and any grid upgrades identified are billed to the applicant.
| Item | Published amount | Notes |
|---|---|---|
| Interconnection fee — NEM-class / Solar Billing Plan systems 1 MW or less | $132 verify current schedule | One-time, non-refundable, per SDG&E's NEM-era schedules |
| Interconnection Request Fee — Rule 21 generator applications | $800 verify current schedule | Non-refundable, invoiced by SDG&E after the request is submitted |
| Supplemental Review / detailed study (ISP, Distribution Group Study) | verify current schedule | Additional non-refundable study fees per the Rule 21 tariff |
Filing here every month?
Design partners get 5 free filings and their territory encoded first — packets produced with dual human review while the software is built.
Typical timeline stages
- Submission — application and documents through DIIS; SDG&E invoices the applicable fee.
- Completeness review — incomplete applications receive a deficiency notice; unresolved deficiencies stall or withdraw the application.
- Engineering review — SDG&E publishes that online applications are processed within 30 days of receipt, with an average under five business days for complete submissions; Supplemental Review or detailed study only if screens fail.
- Approval and agreement — SDG&E publishes a 15-business-day window for delivering a draft Generator Interconnection Agreement on Rule 21 projects, with 90 calendar days to sign.
- Installation and inspection — build to the approved design; obtain the local jurisdiction's final electrical clearance and submit it.
- Permission to operate — issued after SDG&E confirms complete final documentation and any required meter work.
Common deficiency causes
Common ways Rule 21 applications fall short of the published requirements above — each item is a requirement in SDG&E's and the CPUC's cited documents whose absence triggers a deficiency. Not drawn from SunDocket filing data.
- Customer-of-record or service-account data that doesn't match SDG&E's records — mismatches surface at completeness review
- One-line diagram missing the point of interconnection, disconnect, overcurrent protection, or grounding detail
- Missing or unusable meter/placard photo on Fast Track-eligible applications
- Equipment not on the CEC certified equipment lists, or spec sheets missing for non-listed equipment
- Storage nameplate math errors on multi-battery systems, or an undeclared charging source
- Limited- or non-export designs without certified power control system documentation
- Stale form revisions or missing signatures on the interconnection agreement
- Portal sessions timing out mid-application — SDG&E advises assembling all documents before starting the DIIS application
FAQ
How long does SDG&E interconnection take?
SDG&E publishes that online applications through its DIIS portal are processed within 30 days of being received, with an average processing time of less than five business days for complete submissions. For Rule 21 projects that pass review, SDG&E publishes a 15-business-day window for delivering a draft Generator Interconnection Agreement. Incomplete packets receive deficiency notices and take longer, so completeness is the main lever an applicant controls.
What is the SDG&E interconnection application fee?
SDG&E invoices a non-refundable $800 Interconnection Request Fee for Rule 21 generator interconnection requests. NEM-class and Solar Billing Plan systems of 1 MW or less carry a smaller one-time interconnection fee, published as $132 in SDG&E's NEM-era schedules — verify current schedule before filing, as fee schedules are revision-sensitive.
What is DIIS?
DIIS is SDG&E's Distribution Interconnection Information System — the online portal where customers or their contractors submit interconnection applications for rooftop solar, solar-plus-storage, and stand-alone storage, upload supporting documents, and track application status through email-confirmed approval stages.
What is the Solar Billing Plan at SDG&E?
The Solar Billing Plan is SDG&E's net-metering successor program — California's implementation of the Net Billing Tariff, which applies to eligible renewable systems applied for after NEM 2.0 closed to new applications in April 2023. Exported energy is compensated at hourly export prices rather than retail-rate netting. Interconnection under the program is filed through SDG&E's DIIS portal.
What documents does SDG&E require for a Fast Track solar application?
For Fast Track-eligible behind-the-meter projects — SDG&E's published example is service panels under 400 amps and systems under 30 kW — the portal requires an electrical one-line (single-line) diagram and a photo showing the SDG&E meter and the caution placard on the service panel, along with the application data itself. Larger or more complex projects require fuller technical documentation under Rule 21.
What happens if my project fails the Rule 21 screens?
Rule 21 review is a screening ladder. Projects that fail initial screens can move to Supplemental Review, and beyond that to detailed study — SDG&E's Independent Study Process (for projects passing Screen Q but failing Screen R) or a Distribution Group Study submitted during designated application windows. Detailed study is slower, carries additional fees, and can identify distribution upgrades billed to the applicant.
Change log
- Page created from public sources.
Requirements drift. Get the changes.
When this page's change log gets a new entry, we'll email you that entry. Nothing else — see the privacy note.
Sources
- SDG&E — Electric Rule 21 (accessed 2026-08-19)
- SDG&E — Customer Generation (accessed 2026-08-19)
- SDG&E — Solar and Battery Installation Center (accessed 2026-08-19)
- SDG&E — Net Energy Metering (accessed 2026-08-19)
- CPUC — Electric Rule 21: Generating Facility Interconnections (accessed 2026-08-19)
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