The electricity system in California can be thought of as six interoperating subsystems: electricity generators, transmission systems, transmission management, storage, loads, and micro-grids.
Electricity generators are typically large scale plants and can be powered by gas, nuclear, solar, wind, water, geothermal, biomass, or coal. Micro-grids can act as electricity generators, and in the future Virtual Power Plants may provide energy too.
California has over 40 transmission systems ranging from Pacific Gas and Electric (PG&E) and Southern California Edison (SCE), to city run grids.
CalISO provides a marketplace and coordinates electricity generation and transmission.
Currently storage is accomplished in three ways: hydro-electric, dedicated storage such as battery banks, and the emerging VPP and V2G which can draw from batteries in homes and parked electric vehicles.
Loads are the consumers of electricity, and range from single family homes, to factories, to large water pumping stations, to electric vehicle chargers.
Micro-grids can operate as stand alone electricity systems with some source of electricity, and consumers of that electricity. Sources of electricity can be the electricity grid, solar, wind, gas generators, or batteries. Consumers of the electricity can be lights, appliances, machinery, heating and cooling systems, electric vehicle chargers, etc.