Also Energy

California Rule 21/IEEE 2030.5: Understanding the Difference Between Compliance and Readiness

After years of planning, Rule 21 regulations are now a reality. As of June 22, 2020, all behind the meter systems submitting grid interconnection applications with one of California’s Investor Owned Utilities (IOUs) will find new guidelines on the grid interconnection application that require Rule 21/IEEE 2030.5 compliant smart inverters. All behind the meter systems submitting grid interconnection applications on or after June 22 with one of California’s IOUs (San Diego Gas & Electric, Southern California Edison, or PG&E) are subject to the new regulations.

But compliance with current regulations may not guarantee that your project is ready for operations when your utility begins issuing actual event schedules. You will need a SCADA solution on site to relay commands and data between smart inverters on site and utility management systems. Your inverters may or may not include a native system to support this telemetry and control functionality. System owners and operators must consider the importance of futureproofing their projects now to ensure long-term success.

Achieving Rule 21 Compliance Today
The current requirement for grid interconnection is for projects to select a smart inverter from the list of approved devices found on the interconnection application. Approved inverters have all been tested and certified by SunSpec and have demonstrated their ability to support the control and communications functions required under Phase 2 and Phase 3 of IEEE 2030.5, including limiting maximum active power, frequency watt mode, and volt watt mode. A frequently updated list of approved devices can be found at

Ensuring Rule 21 Readiness Tomorrow
The smart inverter functions required under Rule 21 will not become operational until California IOUs build and commission their Distributed Energy Resource Management Systems (DERMS). This development is expected to take about 2 years with an anticipated launch in 2022. At that time, the IOUs will begin operations by enrolling assets and issuing event schedules for your inverters. Owners and operators will need to ensure that their systems can communicate with utility DERMS and relay commands to approved smart inverters in the field. Systems that are prepared today to support telemetry and SCADA functionality are Rule 21 Ready.

Next Steps
Owners and operators for Rule 21 systems in California should be aware of the potential need to plan for a SCADA system to relay data and commands between your inverters and utility DERMS. If your smart inverters do not have a native SCADA interface, you will need to specify a solution for this need in order to be ready for Rule 21 operations in the future. Note that projects which have not addressed this need are still compliant and operational today, creating the potential for an unpleasant surprise later when owners realize they need to purchase, install, and commission new hardware on site when utility event schedules are activated.

For many solar PV developers in the US, Rule 21 is the first time they must account for utility telemetry and control for rooftop projects. For this reason, it is critically important to partner with technology providers who have both the experience and expertise with addressing similar requirements that have been in place for years in mature solar PV market such as Hawaii, where the island’s largest utility has maintained a list of qualified equipment for grid-tied rooftop projects since 2018, and Germany, where a 2008 government policy has required inverters for grid-tied commercial assets to provide advanced functions including dynamic grid support and active & reactive power control. AlsoEnergy has leveraged our experience in these markets to design a SCADA solution for Rule 21 projects that has achieved SunSpec certification as a CSIP 2030.5 aggregator solution.