Rule 21 Tariff
California’s Rule 21, went into effect last September 2017, is a document that describes the interconnection, operating and metering requirements for certain generating and storage facilities seeking to connect to the electric distribution system. The tariff provides customers wishing to install generating or storage facilities on their premises with access to the electric grid, while protecting the safety and reliability of the distribution and transmission systems at the local and system levels.
Per California .gov site: http://www.cpuc.ca.gov/Rule21/
In theory, Rule 21 is a tariff that describes the interconnection, operating and metering requirements for generation facilities to be connected to a utility’s distribution system. The tariff provides customers wishing to install generating or storage facilities on their premises with access to the electric grid while protecting the safety and reliability of the distribution and transmission systems at the local and system levels.
Each investor-owned utility is responsible for administration of Rule 21 in its service territory and maintains its own version of the rule:
|PG&E||Rule 21 Tariff||Rule 21 Website|
|SCE||Rule 21 Tariff||Rule 21 Website|
|SDG&E||Rule 21 Tariff||Rule 21 Website|
Rule 21 makes California the first state to require smart inverters in solar systems. The basic definition of a “smart inverter” is one that is able to communicate with the utility. See at the bottom of the page inverters that meet Rule 21.
Rule 21 is broken up into 3 Phases:
1. September 2017: Phase 1 Autonomous Functions
2. 2018: Phase 2 Communication Protocols
3. TBD: Phase 3 Advanced Functions
California’s Electric Rule 21 was created to implement greater interconnectivity between solar smart inverters and utility distribution centers to ensure a safer, more reliable grid. An increasing amount of residential and commercial solar system installations increased energy production to the grid, the existing utility communication network leads to preventable power surges, voltage sags, and blackouts.
Rule 21 solves these voltage fluctuations by pushing solar inverters to facilitate a bidirectional communications link to the utility. By having access to the exact production levels from residential solar systems, the utility will finally have accurate information in order to maintain a constant and stable electrical flow.
Rule 21 represents increased efforts to ensure an advanced grid functionality with a two way power flow, as solar energy continues to widely integrate into the energy mix.Tags: metering requirements, rule 21, rule 21 tariff, smart inverter