Order No. 1920 requires long-term scenarios in regional transmission planning

Order No. 1920, issued in RM21-17-000 on 13 May 2024, requires transmission providers to conduct long-term regional transmission planning on a horizon of at least twenty years, using multiple plausible scenarios, and to adopt a cost allocation method for the facilities that planning selects.

The rule's significance for interconnection customers is indirect but large. Network upgrades identified through regional planning are allocated under planning cost allocation rules. Upgrades identified through interconnection study are allocated to interconnection customers. Where the line falls between those two categories decides whether a given reinforcement appears on a developer's cost estimate or in a regional rate base.

Order No. 1920-A, in RM21-17-001, addressed rehearing arguments including the role of states in the long-term planning process. The states' role is not decorative: agreement on cost allocation is the usual point at which regional plans stall.

Compliance filings define scenario inputs, including load growth assumptions. Those assumptions are where large load forecasts enter the planning record formally, rather than as trade press estimates.

What to watch: whether any region's compliance construct explicitly shifts a category of interconnection-driven upgrade into regional cost allocation.