SDG&E Transmission System Overview
The San Diego Gas & Electric’s (SDG&E) transmission system (69 kV and above) is under the operational control of the California Independent System Operator (CAISO). Interconnection of generation facilities to the SDG&E transmission system is subject to the CAISO Federal Energy Regulatory Commission (FERC) approved Generation Interconnection Procedures (GIP) tariff. Projects proposing to interconnect to the SDG&E transmission system (transmission lines and transmission substations) are studied in a cluster. In order to evaluate the feasibility of an individual project, as far as transmission capacity is concerned, all projects in that cluster need to be considered to identify the available capacity.
The transmission system included in the map on this web site provides the transmission information regarding the outlet capability from the distribution substation by indicating how the distribution substation/system is integrated into the transmission network. This provides interconnecting customers information regarding the power flow capability from the distribution substation onto the transmission system.
For information on interconnecting to the SDG&E transmission system please refer to the following web site:
SDG&E’s transmission system, and generally the CAISO managed transmission grid, is interconnected in a network configuration. The networked nature of the transmission system requires a specific suite of studies to identify the available capacity on any transmission or substation within the network. The networked characteristic of the transmission system also provides flexibility, unlike a radial system (distribution), in redistributing the power flow when an element of the network is out of service for maintenance or is forced out.
Distribution System Available Capacity
Substation area location
Accessing the Map
In order to view the map, you are required to register with SDG&E. Once registered, an email that contains a web link, a username with password, and instructions to access and use the map will be sent to your email address.
Download Form and Register
Need Help Viewing the Map?
If you need assistance in viewing/registering for the interactive map, contact us via email or phone (858) 636-5581 during regular business hours (Mon-Fri, 7am-4pm)
Instructions to access and use the map
The website is intended to provide an initial screening of generation interconnection projects. A detailed study is required to confirm all distribution upgrade costs. The interconnection customer should not rely on any cost estimates on this website as they are only intended to provide a general perspective.
The interactive substation area map is intended to show the general substation area and not a specific point of interconnection. The interconnection customer must meet with SDG&E to confirm the substation interconnection point.
The interactive feeder map is not intended for an interconnection customer to identify the exact location for interconnection. The interconnection customer must meet with SDG&E to confirm the interconnection point.
Feeder branch routes are not shown on the interactive map as they generally have limited capacity for interconnection. Should a branch be proposed as the point of interconnection it is likely that potentially significant distribution branch upgrades will be required to facilitate the interconnection.
The sum of the generation capacity on the circuit and substation cannot exceed the rated capacity of the substation area. For example: If a substation rated capacity is 12 MW and the associated substation three (3) circuits have 6 MW each of rated capacity the maximum proposed generation cannot exceed 12 MW when summing the proposed generation capacity on the substation and circuits.
Negative available generation capacity indicates over allocation of generation capacity and will result in zero available capacity on the feeder. This indicates that proposed projects have already been submitted for interconnection related to a feeder or substation area and the generation project’s capacity has been allocated for their queue position. The SDG&E distribution system is limited to the positive available generation capacity shown on the substation area or feeder and interactive map.
The interactive website map is not intended for construction.
The available generation capacity is updated once a month.
Interconnection to the distribution system may also impact the transmission system and will require additional analysis.
All interconnection requests shall follow applicable interconnection requirements.
Generation Capacities for Feeders
Minimal Impact Capacity
An interconnection request seeking interconnection of 15% or less of feeder rated capacity minus existing generation capacity minus distribution queue position capacity that is estimated to cost no more than $235K.
See note 1 in the feeder available generation Table 1 that provides all assumptions.
Total Generation Capacity
Total feeder rated capacity minus existing generation capacity minus distribution queue position capacity. Cost to interconnect projects which have a generation capacity of greater than 15% of feeder rated capacity are estimated to exceed $235K and will require separate cost calculation for each specific project proposed.
See Note 2 in the substation area available generation Table 2 that provides all assumptions. Please read the general notes with additional information.
Generation Capacities for Substation Areas
Minimal Impact Capacity
An interconnection request seeking interconnection of 15% or less of substation area rated capacity minus existing generation capacity minus distribution queue position capacity that is estimated to cost no more than $235K.
See Note 1 in the substation area available generation Table 1 that provides all assumptions.
Total Generation Capacity
Total substation area rated capacity minus existing generation capacity minus distribution queue position capacity. Cost to interconnect projects which have a generation capacity of greater than 15% of substation area rated capacity are estimated to exceed $235K and will require separate cost calculation for each specific project capacity proposed.
See Note 2 in the substation area available generation Table 2 that provides all assumptions.
Substation Area Available Generation Capacity Table 1
Feeder Available Generation Capacity Table 2