Flexible transmission allocation would allow Western solar projects to proceed

Enabling renewable projects in the Pacific Northwest to obtain flexible transmission rights could help states reduce electricity costs and meet renewables targets, suggests a report. The approach could also have utility in most of the West.

June 10, 2025 William Driscoll

Image: pixabay

Traditional requirements for new generators in the Pacific Northwest to have long-term firm contracts for point-to-point transmission could be replaced with flexible transmission allocation, enabling more solar on the grid and reducing system costs, according to a report from Sylvan Energy Analytics and GridLab.

The report focuses on the region served by the Bonneville Power Administration (BPA), a federally owned hydropower and transmission utility. Solar and other generating projects in the region must secure both interconnection, or the right to connect to the grid, and transmission rights, or the right to move power from their point of interconnection to another point on the grid, explained Casey Baker, senior program manager with GridLab.

The same requirements apply to generating projects throughout the “non-ISO” West, a multi-state area excluding utilities served by grid operators CAISO in California and SPP in the central U.S., Baker said.

Many utilities across the non-ISO West require a generating project to secure long-term firm, 24/7 transmission rights before contracting for a resource or allowing it to be bid into an RFP, Baker said. “This is a problem renewable developers face when trying to get an offtaker for their project,” he noted.

Baker suggested the report’s findings could thus be applicable across the non-ISO West.

The requirement for long-term firm transmission access has been satisfactory for utilities in the BPA region, as they have been able to obtain the transmission rights on a project-by-project basis to deliver generation across the BPA transmission system.

Yet while most of BPA’s transmission is locked up in firm, 24/7 contracts with existing generators, many transmission paths have available capacity much of the time. In the words of the report, BPA’s transmission network “is much less physically constrained than it is contractually constrained.”

Indeed, most BPA transmission paths have experienced congestion in fewer than 10 hours per year on average in recent years, the report found.

Meanwhile, the contractual constraints on transmission could be slowing the deployment of renewables projects needed for many states to reach their renewables targets, the report suggests.

The report considers how to optimize the use of BPA’s transmission system by flexibly allocating transmission rights. Renewable resources could then share rights to use the transmission system, at the cost of being subject to some curtailment.

The approach of sharing the transmission system is essentially the approach used in many grid regions, Baker said, “where the price signal or security constrained economic dispatch dictates who gets to use the transmission.”

In the solution proposed by the report, each utility served by BPA could actively manage its portfolio of long-term fixed transmission rights “on behalf of customers” to minimize costs while maintaining reliability.

The report describes how to develop a scheduling model for allocating transmission, focusing on “dynamic transmission rights based on the needs of the load,” Baker said.

Two chapters of the report describe methods for estimating curtailment levels, first in long-term planning, and then in RFP processes.

The report is titled “Toward a more holistic and adaptive treatment of BPA transmission rights in Northwest utility planning and procurement processes.”

This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: editors@pv-magazine.com.