Interconnection glossary

The terms that come up on every interconnection application, defined in plain language — with links to the utility pages in the requirements wiki where each one actually appears.

Permission to operate (PTO)

The utility's written authorization to energize a generating system and run it in parallel with the grid. It comes after installation, the local jurisdiction's inspection, and complete final documentation — and every utility we cover is explicit that the system stays off until PTO is granted. Missing final documents are one of the most common reasons PTO stalls.

Appears in: PG&E · SCE · SDG&E · APS · TEP · SRP · NV Energy · FPL

Deficiency notice

The utility's written notice that an application is incomplete or defective, listing what's missing. Response windows run against the applicant — under PG&E's Rule 21, for example, 10 business days after a first notice and 5 after a second — and deficiencies left unresolved can stall the application, cost queue position, or have it deemed withdrawn. New York's SIR requires the utility to include a detailed explanation of the deficiencies with each notice.

Appears in: PG&E · SCE · SDG&E · Con Edison · National Grid

Initial Review / Supplemental Review

The two rungs of a screening-based review ladder. Initial Review is the first, fastest stage — the application is checked against a set of technical screens, and projects that pass all of them interconnect without further study. Supplemental Review is the deeper second look for projects that fail specific screens; it usually carries its own fee and clock (under Rule 21, 20 business days when the fee is pre-paid). Failing Supplemental Review moves a project to detailed study.

Appears in: PG&E · SCE · SDG&E · National Grid · Eversource · Xcel

Screens

The pass/fail technical tests an application is checked against during review — covering things like generation penetration on the circuit, voltage and power quality, fault current, and protective coordination. Each framework names its own set: Rule 21 letters its screens (most behind-the-meter projects are exempt from Screen Q), the NY SIR runs preliminary Screens A–F and supplemental Screens G–I, and Arizona's ACC rules key their levels to screens A through J.

Appears in: PG&E · SCE · SDG&E · Con Edison · National Grid · TEP · SRP

CESIR

The Coordinated Electric System Interconnection Review — the detailed study a New York utility performs under the SIR to evaluate a project's impact on its system. It's completed within 60 business days of authorization, fee payment, and a complete design package, extendable by up to 40 business days by agreement. In Con Edison territory a CESIR can be required even for mid-size projects that would screen through elsewhere, because much of the territory runs on underground secondary network systems.

Appears in: Con Edison · National Grid

Pre-application report

A data report the utility prepares about conditions at a proposed site — hosting capacity, existing equipment, constraints — before a formal application is filed. It's a scoping tool for larger projects, not an application, and it carries a fee (the NY SIR publishes $750; Massachusetts tiers it by size). Optional in most frameworks, but National Grid's Massachusetts tariff requires it at 250 kW and above.

Appears in: PG&E · SDG&E · Con Edison · National Grid · APS · Eversource

Single-line diagram

A simplified electrical drawing that shows a system's components and connections as one line per circuit — the point of interconnection, disconnects, overcurrent protection, and grounding. It's the near-universal packet requirement, and a single-line missing one of those details is among the most commonly cited deficiency causes. Some utilities call it a one-line diagram.

Appears in: PG&E · SCE · SDG&E · Con Edison · National Grid · FPL · Eversource

Three-line diagram

An electrical drawing that shows all conductors — each phase plus neutral and ground — rather than collapsing them into one line. Utilities require it where per-phase and grounding detail matters: APS requires a three-line for all systems with static inverters (a one-line is accepted only for residential single-phase, load-side connections), and New York utilities may require one for PV and battery designs on three-phase systems.

Appears in: APS · TEP · SRP · Con Edison · National Grid · NV Energy

Interconnection agreement

The contract between the system owner and the utility that authorizes parallel operation and sets the terms for it. Every process we cover requires one — as a standardized statewide form (the NY SIR's Appendix A contract), a utility tariff form, or an e-signed document routed through the application portal. Missing signatures and stale form revisions are recurring deficiency causes.

Appears in: PG&E · SCE · SDG&E · APS · TEP · SRP · National Grid · Xcel

Net metering

A billing arrangement that credits energy a system exports against energy the customer consumes, historically at or near the retail rate. Many states have closed or reshaped their original net-metering programs — California replaced NEM 2.0 with the Solar Billing Plan, and other states run successor or modified programs — so which program an application files under is one of the first things a packet has to get right.

Appears in: Duke · FPL · Eversource · National Grid · NV Energy · Xcel

Net billing / Solar Billing Plan

California's successor to Net Energy Metering 2.0 — the state's implementation of the Net Billing Tariff, offered by each investor-owned utility as the Solar Billing Plan. It applies to eligible renewable systems applied for after NEM 2.0 closed in April 2023, and compensates exported energy at hourly export prices rather than retail-rate netting. Interconnection under the program files through each utility's own portal.

Appears in: PG&E · SCE · SDG&E

Rule 21

California Electric Rule 21 — the interconnection tariff the CPUC requires of its jurisdictional utilities. It governs how generating facilities (solar, storage, and hybrids) connect in parallel with the distribution system: the screening ladder, review timelines, and fees. PG&E, SCE, and SDG&E each file their own version, so the frame is shared but the forms, portals, and fee schedules are utility-specific. See the California hub and Rule 21 vs the NY SIR.

Appears in: PG&E · SCE · SDG&E

NY SIR

The New York State Standardized Interconnection Requirements — the Public Service Commission framework governing distributed generation and energy storage with an AC nameplate rating of 5 MW or less. Unlike California's utility-filed tariffs, one statewide SIR document sets the applications, screens, studies, fees, and timelines for all of the state's investor-owned utilities; the edition in force at our last review is effective February 9, 2026. See the New York hub.

Appears in: Con Edison · National Grid

ACC DGIR

The Arizona Corporation Commission's Distributed Generation Interconnection Rules (A.A.C. R14-2-2601 through R14-2-2628, effective February 25, 2020). They set the application levels — Level 1 Super Fast Track, Level 2 Fast Track, Level 3 Study Track — plus screens and review clocks for Arizona's ACC-regulated utilities, APS and TEP. SRP is a political subdivision of the state, not ACC-regulated, and follows its own Handbook instead. See the Arizona hub.

Appears in: APS · TEP · SRP

MN DIP

The Minnesota Distributed Energy Resource Interconnection Process — the statewide framework the Minnesota PUC approved in 2019 under Minn. Stat. § 216B.1611 for interconnecting DER of 10 MW and under. It defines a Simplified process for certified inverter-based systems no larger than 20 kW, a Fast Track process, and a Study process, plus the standard MN DIA interconnection agreement. Xcel's Minnesota applications follow it.

Appears in: Xcel

PowerClerk

A widely used online interconnection application platform. Several utilities in the wiki run intake through PowerClerk-based portals — each configured with that utility's own forms, document requirements, and e-signature routing, so experience with one utility's PowerClerk doesn't transfer as directly as the shared brand suggests.

Appears in: APS · TEP · SRP · SCE · Con Edison · NV Energy · Eversource

UL 1741 (SB)

The safety certification standard for inverters and other interconnection system equipment. Supplement SB certifies that an inverter conforms to IEEE 1547-2018's smart-inverter capabilities, and it has become a hard requirement in several territories — California's CPUC directive required UL 1741 SB compliance as of August 29, 2023, and New York's SIR expects inverters certified to UL 1741 with supplement SB, set per the utility's technical requirements.

Appears in: SCE · Con Edison · National Grid · APS · TEP · SRP · Eversource · Duke · Xcel

IEEE 1547-2018

The national technical standard for interconnecting distributed energy resources with the grid — it specifies voltage and frequency ride-through, power quality, and grid-support functions DER equipment must provide. Utility technical manuals commonly require equipment conformant to IEEE 1547-2018, demonstrated in practice through UL 1741 SB certification.

Appears in: APS · TEP · SRP · NV Energy · Eversource

Certified equipment list

A published list of equipment pre-approved for interconnection — in California, the CEC's lists of eligible modules, inverters, and batteries; elsewhere, utility- or lab-maintained certified lists. Equipment not on the applicable list needs supporting documentation (or a variance request) and reliably slows review; "equipment not on the certified list" is a stock deficiency cause across utilities.

Appears in: PG&E · SCE · SDG&E · APS · TEP · Duke

Power control system (PCS)

Certified control hardware and software that limits how much power a system can export or import at the point of interconnection. Limited-export and non-export designs rest on the PCS: the utility approves the design on the strength of documentation showing the control is certified to enforce the stated limit, and missing PCS documentation is a named deficiency cause on all three California IOU pages.

Appears in: PG&E · SCE · SDG&E