The working group has pursued development of advanced inverter functionality over three phases. A power inverter, or inverter, is an electronic device or circuitry that changes direct current to alternating current.

Phase I considered autonomous functions that all inverter-connected distributed energy resources in California will be required to perform. 
Phase 1 Recommendations and Test Plan Documents

Phase II considered the default protocols for communications among investor-owned utilities, distributed energy resources, and distributed energy resource aggregators.

Phase III is considering additional advanced inverter functionality that may require communications.
Phase 3 Documents