Rule 21 vs the NY SIR
California and New York solved the same problem with opposite architectures: three utility-filed tariffs versus one statewide standard. Here's what actually changes when your crews work both — drawn from our California and New York pages.
Governance: utility-filed tariff vs statewide standard
Rule 21 is a tariff the CPUC requires of its jurisdictional utilities — but PG&E, SCE, and SDG&E each file their own version. The frame is shared; the document, the portal, the forms, and the fee table are the utility's. Fees change by advice letter, utility by utility.
The NY SIR is one document from the Department of Public Service, adopted by the Public Service Commission, that governs DER of 5 MW or less across all of the state's investor-owned utilities — Con Edison and National Grid upstate among them. The SIR itself publishes the process, most of the fees, and the clocks; utilities layer portals and technical documents (Con Edison's DG checklists, National Grid's ESB 756) on top. What changes instead is the edition: the SIR is revised statewide, and our pages note the edition in force at review (effective February 9, 2026 verify current edition).
The practical difference in maintenance burden: in California you track three tariffs that drift independently; in New York you track one standard plus each utility's technical layer.
Pathway structure: screening ladder vs sized tracks
Rule 21 sorts by screening outcome. Every project enters the same ladder: Initial Review runs the technical screens, and passing them all means interconnecting without further study. Failing specific screens drops a project to Supplemental Review (its own fee and clock), and failing that to Detailed Study. Size matters mainly through screen exemptions — CPUC Decision 19-03-103 exempted NEM and inverter-based non-NEM projects of 1 MVA or less from Screen Q, which keeps most behind-the-meter projects on the fast path.
The SIR sorts by size first. Systems 50 kW or less get a six-step expedited process with no screens to speak of — a 10-business-day completeness and eligibility review, then install, test, and accept. (Inverter-based systems above 50 kW up to 300 kW certified to UL 1741 SB can also use it.) Everything above that, up to 5 MW, runs the eleven-step full process: preliminary Screens A–F, optional supplemental Screens G–I, and — where required — the CESIR, a formal 60-business-day study with its own fee and design-package prerequisite. There's no CESIR equivalent baked into Rule 21's ladder; Detailed Study plays that role only for projects that fail their way down to it.
One more structural wrinkle: in Con Edison's underground secondary network areas, the SIR lets the utility require additional review case by case, so a CESIR can land on a mid-size NYC project that would have screened straight through in California — or upstate.
Fee structure
California fees are per-utility and program-dependent; New York's are mostly set in the SIR itself. Every amount below is revision-sensitive — the sources and access dates are on the linked utility pages.
| Item | California (Rule 21, per utility) | New York (SIR) |
|---|---|---|
| Application fee — small residential-class | Varies by utility and program: $145 (PG&E NEM-class ≤1 MW), $75 (SCE Solar Billing Plan), $132 (SDG&E NEM-class ≤1 MW) verify current schedules | None for systems 50 kW or less — the SIR says so directly |
| Application fee — larger projects | $800 interconnection request fee at all three IOUs for Rule 21 generator applications verify current schedules | $750 above 50 kW per Con Edison's application page, applied toward interconnection costs if the project completes verify current schedule |
| Second-stage review | Supplemental Review $2,500, non-refundable ($0 for NEM-class ≤1 MW at PG&E) verify current schedules | Supplemental screening $2,500 at election, with actual costs up to $5,000 billable at reconciliation verify current schedule |
| Detailed study | Deposit-based study fees per each utility's tariff (e.g., $10,000 Detailed Study deposit for smaller facilities at PG&E) verify current schedules | CESIR invoiced from a utility cost estimate before study start; project-specific |
| Pre-application report | Offered via utility forms; amounts per utility verify current schedules | $750, non-refundable; credited toward the application fee if the application lands within 15 business days of the report verify current schedule |
| Reconciliation habit | Flat fees at submission (PG&E, SCE) or invoiced (SDG&E); upgrades billed to the applicant | Cost reconciliation is a formal, final step of the full process; system-modification payments are staged by estimate size |
Timeline clocks
Both regimes run on business-day clocks, and the front ends look surprisingly alike. The figures below are from PG&E's filed Rule 21 tariff and the SIR edition effective 2026-02-09, as accessed on the dates cited on the utility pages verify current documents.
| Stage | Rule 21 (PG&E's filed tariff) | NY SIR |
|---|---|---|
| Completeness review | 10 business days to state complete/incomplete in writing | 10 business days for completeness (and, ≤50 kW, eligibility) |
| First screening stage | Initial Review results within 15 business days of validation | Preliminary screening (Screens A–F) results within 15 business days |
| Second screening stage | Supplemental Review within 20 business days of Initial Review, fee pre-paid | Supplemental screening (Screens G–I) within 20 business days of authorization and fee |
| Detailed study | Detailed Study on a study timeline — no fixed tariff clock cited on our pages | CESIR within 60 business days of authorization, fee, and complete design package; +40 by agreement |
| Applicant-side deadlines | Deficiency cure: 10 business days after a first notice, 5 after a second; one extension up to 20 | 30 business days on information requests, 15 on contract signatures, 10 on screening-decision notices |
| End of process | PTO typically 5–10 business days after complete final documentation (stated max 30, PG&E) | Verification test within 10 business days of completed-installation notice; acceptance letter within 5 business days of a successful test (≤50 kW) |
The divergence isn't the clocks — it's where the time risk sits. In California the long tail is falling off the fast path into Supplemental Review or Detailed Study. In New York the CESIR is a normal, scheduled part of mid-size projects (and, in network areas, sometimes small ones), so the 60-day study is planned rather than feared.
Packet differences
| Packet element | California (Rule 21) | New York (SIR) |
|---|---|---|
| Application form | Each utility's own forms and portal flows (Your Projects, OIAS/GIPT, DIIS) confirm current revisions | Standardized statewide appendix forms — inverter-based (Appendix B) or non-inverter (Appendix C) — plus the utility's documentation checklist confirm current revisions |
| Completeness yardstick | The utility's program requirements; portals pre-populate account data and surface mismatches immediately | The SIR's Appendix F checklist — the review is administrative and literal against it |
| Diagrams | Single-line diagram showing point of interconnection, disconnects, overcurrent protection, grounding | Single-line, plus a three-line where required for PV/battery designs on three-phase systems; site plan expected |
| Equipment proof | CEC certified equipment lists; UL 1741 SB / Smart Inverter Phase 2 per CPUC directive | Inverters certified to UL 1741 (supplement SB) with settings per the utility's technical requirements (e.g., ESB 756 at National Grid) |
| Storage | Charging source and export mode declared; certified power control system documentation for limited/non-export designs | ESS application requirements in the SIR's Appendix K |
| Consumer / site paperwork | CSLB contractor license; California Solar Consumer Protection Guide disclosures for residential sales | Customer authorization letter; property-owner consent (Appendix H) and site-control certification (Appendix J) where applicable |
| Agreement | Utility agreement forms per program confirm current revisions | One standardized statewide contract (Appendix A), executed during the process |
| Closeout | Local jurisdiction's final electrical clearance uploaded; then PTO | Verification testing (utility witness optional; certification ≤50 kW), acceptance letter, and — full process — cost reconciliation |
Takeaways for multi-state teams
- Track different things drifting. California requires watching three utility tariffs and fee tables that move by advice letter; New York requires watching one SIR edition plus per-utility technical bulletins.
- Size your expectations differently. A 200 kW project is a screening question in California and a probable-CESIR project in New York — cost and schedule it that way.
- The checklists are literal in New York. Appendix F completeness review rewards packet discipline directly; in California the equivalent discipline is account-data hygiene and current form revisions.
- Applicant clocks bite in both. Missed cure windows withdraw applications in California; missed information-request and signature windows cost queue position in New York.
- Neither regime forgives stale numbers. Every figure on this page is flagged for a reason — verify the current tariff or SIR edition before budgeting or promising a date.
Per-utility detail, with sources cited and dated: PG&E, SCE, and SDG&E for Rule 21; Con Edison and National Grid for the SIR. State context: California hub · New York hub. Vocabulary: interconnection glossary.
Filing on both coasts?
Design partners get 5 free filings and their territory encoded first — packets produced with dual human review while the software is built.