California Code, Public Utilities Code - PUC § 8370

(a) “Customer” means a customer of a local publicly owned electric utility or of a large electrical corporation. A person or entity is a customer of a large electrical corporation if the customer is physically located within the service territory of the large electrical corporation and receives bundled service, distribution service, or transmission service from the large electrical corporation.

(b) “Distributed energy resource” means an electric generation or storage technology that complies with the emissions standards adopted by the State Air Resources Board pursuant to the distributed generation certification program requirements of Section 94203 of Title 17 of the California Code of Regulations, or any successor regulation.

(c) “Large electrical corporation” means an electrical corporation with more than 100,000 service connections in California.

(d) “Microgrid” means an interconnected system of loads and energy resources, including, but not limited to, distributed energy resources, energy storage, demand response tools, or other management, forecasting, and analytical tools, appropriately sized to meet customer needs, within a clearly defined electrical boundary that can act as a single, controllable entity, and can connect to, disconnect from, or run in parallel with, larger portions of the electrical grid, or can be managed and isolated to withstand larger disturbances and maintain electrical supply to connected critical infrastructure.