Colorado’s Public Utilities Commission is pushing to require the state’s utilities to publish detailed, node-level capacity maps as part of the push to enable distributed energy resources — and flexible interconnection.
As load growth has accelerated and interest in flexibility has risen, one major challenge has been a lack of visibility: where does extra capacity exist during non-peak hours? Utilities are grappling with pricey upgrade proposals, and often balking at flexible resource deployment proposals. In Colorado, this tension has been on full display in the docket for Xcel Energy’s latest distribution system plan, filed late last year.
Xcel proposed significant capital investments to upgrade the distribution system, and a case-by-case approach to flexible connections — a model that California’s PG&E has already experimented with — that would help mitigate those costs. But flexibility and distributed generation proponents pushed back, arguing the utility needed to develop a standardized tariff for interconnection, and that Xcel’s lack of transparency surrounding grid capacity would hold back flexibility.
In an oral decision in late October, the commission largely sided with the intervenors, expressing frustration with Xcel’s approach to load growth. They required the utility to remove restrictions on its hosting capacity maps, and develop a standardized flexible interconnection tariff for both generation and load. (A written ruling is expected this month.)
The maps are key to making better use of the existing grid, explained Sky Stanfield, a partner at Shute, Mihaly & Weinberger LLP who represents the Interstate Renewable Energy Council, an intervenor in the proceedings in Colorado. Xcel’s hosting capacity analysis should serve as a starting point for future distributed asset and flexibility programs.
“If you want generators or load customers to be able to locate the places on the grid where there is existing capacity, so that we’re using existing capacity first, you have to tell them where it is and when it is,” Stanfield said. “Flexible service connections, whether it’s load or generation, are really about managing the temporal differences that happen in grid capacity throughout the day and throughout the year.”
Fixing the map problem
The hosting capacity map Xcel had been relying on prior to the ruling was “literally worthless,” Stanfield said. This was because the public version was blurred to hide line locations, and more detailed maps were only available to those who signed “commercially impossible” non-disclosure agreements.
These NDAs, Stanfield explained, required signatories to maintain undefined cybersecurity practices and didn’t contain carve-outs for information that the maps might contain that was also publicly available, potentially creating legal liability. In essence, from IREC’s perspective at least, the agreements required signatories to maintain the same level of data security as a major utility — a heavy lift for most developers, municipalities, and corporations.
The generation maps Xcel published weren’t dynamic, but reflected availability only during the most constrained hour of the year. On the load side, hosting maps were only made available to participants in the PUC proceeding via NDA.
Xcel argued these restrictions were paramount for grid security. Revealing the specific locations of distribution lines, the utility explained, could make the critical infrastructure vulnerable to attack.
The commission, however, rejected that reasoning. Within 60 days of the written order, Xcel must update its maps using data no older than September 2025; by the end of 2026, the utility will be required to update those maps monthly. By the end of 2027, the commission ordered, it must perform a more temporally granular analysis, potentially modeling all 8,760 hours of the year rather than just peak constraints.
Xcel will also be required to enable data downloads, so that EV charging companies, for example, could layer grid capacity maps with real estate data, or solar developers could combine capacity with land availability and transmission corridor maps. It’s a potentially transformative update, Stanfield said, that could help clear out the utility’s queues: “Projects will be applying knowing with much more accuracy whether there’s capacity…or not,” she explained.
The PUC’s decision arrives at a crucial moment for Colorado’s distributed dispatchable generation program, which is designed to leverage third-party-owned solar and storage to support grid reliability but faces a tight turnaround for developers to apply and get projects online.
Flexible interconnection for distribution
On top of more visible data, the commission’s order also requires Xcel to create a flexible interconnection tariff for generation and load.
A tariff was in fact required by state statute in 2024, but Xcel had proposed a case-by-case approach — which the commissioners characterized as failing to comply with the statute entirely. But as far as how to compel the utility to comply, they were partially split over whether to offer an incentive versus some type of regulatory consequence.
It’s a unique order, because while utilities around the country have established similar frameworks for load at the transmission level, Xcel will now do so at a distribution level. That likely means the tariff won’t target massive data center loads, but rather EV charging stations, school districts, or mid-sized commercial facilities.
Xcel’s incremental approach to flexible interconnection “fails to acknowledge the urgency” of the moment, commissioner Tom Plant said. “The company should be implementing it with an eye toward how it integrates then later down the line with grid DERMS, but we don’t wait for grid DERMS in order to comply with the statute.”
