As California pushes for dramatic expansion of small-scale power systems producing 12,000 MW of power under a gubernatorial plan, it raises the question of whether the historical divide between what utilities claim as their distribution systems and the grid operator as its transmission territory must be revisited to maintain reliable power service. The disparity between what utilities claim as their own controlled distribution system and the larger grid was at issue this week in a California Energy Commission workshop. The push for more renewables has brought to the forefront the question of where that murky dividing line lies between transmission and distribution infrastructure. Traditionally, the California Independent System Operator has operated the state\u2019s transmission system, consisting of long distance high voltage power lines connected to big, centralized power stations. At the local level, utilities have controlled connections to lower voltage lines in what\u2019s traditionally called the distribution system. CAISO is charged with overall grid reliability, encompassing both transmission and distribution. It\u2019s responsible for the flow of power to homes and businesses, although its control is limited to the transmission system. Meanwhile, there\u2019s no set definition of lower voltage distribution lines--with each utility defining them differently. Even the Federal Energy Regulatory Commission has no concrete classification of the difference between transmission and distribution infrastructures. Enter into this grey area Governor Jerry Brown\u2019s call for 12,000 MW of distributed alternative energy to start feeding into the grid. That amount of distributed power is expected to significantly impact not only utility low voltage power lines, but also flows on the high-voltage infrastructure. That\u2019s why CAISO thinks it may need to be involved in planning where the facilities are placed and how much power they produce in order to keep meeting its responsibility. Utilities disagreed when the issue was aired at a June 22 California Energy Commission workshop. Gary Holdsworth, Southern California Edison project manager, and other utility representatives, objected to having their distribution system studies be folded into CAISO\u2019s transmission planning process, which is under development. Utility representatives noted that they are grappling with thousands of interconnection requests from renewable supplies. Edison, for example, has 3,000 MW of alternative supplies in its distribution interconnection queue. To date, CAISO does not take into account systems under 1 MW, and nearly all residential solar units are smaller than that. If, for example, dozens of home rooftop photovoltaic systems are suddenly curtailed on a summer afternoon by cloud cover, the flow of the system would be disrupted, with the grid operator responsible for making up the shortfall of which it has no information. That\u2019s why the uncertainty surrounding the expected surge in the number of distributed energy installations, including their size and locations, is a key issue for CAISO, said Neil Millar, grid operator senior director of planning. He added CAISO urges coordination on distribution plan studies to accommodate higher levels of alternative power supplies. The grid operator is attempting to include more intermittent renewable supplies following passage of the state\u2019s 33 percent renewable portfolio mandate earlier this year. Brown\u2019s 12,000 MW of distributed energy comes under the 33 percent mandate and may complicate the task. Jon Eric Thalman, Pacific Gas & Electric director of regulatory strategy, said the company is trying to figure out how best to handle the surge in interconnection requests and \u201chow to better integrate and assess the system impacts.\u201d He added, however, that \u201ceach one needs to be looked at individually.\u201d Coordinated planning and modeling of the 12,000 MW distributed renewable policy is necessary \u201cto determine the practicality of these policy initiatives and to maintain overall grid reliability,\u201d Steven Kelly, Independent Energy Producers policy director, told Current. The three investor-owned utilities\u2019 plans for incorporating higher levels of distributed generation, as well as remote, renewable project supplies, are to be detailed in their so-called \u201csmart grid\u201d deployment plans due to the California Public Utilities Commission July 1. Utilities, and some observers, also fear that if electric vehicle use surges, grid reliability may be further undermined. Electric vehicles draw power from the distribution system. Vehicle charging can draw as much power as a whole house. State regulators are grappling with how to allocate the cost of necessary distribution system upgrades to accommodate them. Energy Commission chair Bob Weisenmiller raised concerns about three separate deployment plans from the individual utilities. This, he added, is at a time of experimentation as the state enters a new energy frontier and requirement for a single interface with CAISO.