Interconnection Guidelines

Note: In June 2007, the Arizona Corporation Commission (ACC) initiated a rulemaking process (Docket No. RE-00000A-07-0609) to establish statewide interconnection standards for distributed generation (DG). Draft proposed rules were published for comment in June 2015. This proceeding is still in progress. Until new official rules go into effect, the commission has recommended that the utilities use the Interconnection Document as a guide. This document applies to systems up to 10 megawatts (MW) in capacity. 

The state’s utilities independently developed interconnection agreements for distributed generation (DG) prior to the ACC’s ongoing proceeding to establish statewide standards. The Salt River Project (SRP), which is not regulated by the ACC on utility matters, developed DG interconnection guidelines and an interconnection agreement based on draft rules and a report released by the ACC in 1999 and 2000, respectively. SRP’s rules include technical protection requirements, a flow chart of interconnection procedures, and a two-page interconnection application. The rules establish separate requirements for units based on system capacity:

• Class I: 50 kilowatts (kW) or less, single or three-phase
• Class II: 51 kW to 300 kW, three-phase
• Class III: 301 kW to five megawatts (MW), three-phase
• Class IV: greater than 5 MW, three-phase

Tucson Electric Power (TEP) and Arizona Public Service (APS) — the other two major electric utilities in Arizona — have similarly established their own interconnection procedures for DG systems. It is likely that Arizona’s regulated utilities will adopt the ACC’s interconnection standards when the final rules are adopted.