At a Colorado Public Utilities Commission evidentiary hearing May 16, 2025, PUC trial staff and intervening community‑solar advocates presented competing methods for adjusting the value of community solar garden fixed bill credits over time.

The conflict centers on how to reflect inflation or cost changes in a credit that subscribers select as a stable, multi‑year option. Staff proposed a mechanism it describes as cost‑based and smoothing: a fixed credit that remains static for the first five years after the vintage year, then in the sixth year “matures” into a five‑year rolling average calculated from published annual TAR (total aggregate retail) values. Dr. Nick Bongiardina, staff analyst, summarized the approach: “Under staff's proposal, a fixed credit vintage would be static for the first 5 years starting in the year the CSG applied for interconnection. In the sixth year, the vintage would mature and transition to a 5 year rolling average.”

Black Hills witness Daniel S. Ahrens opposed indexing fixed credits to CPI‑U, arguing that general inflation indexes have little direct relationship to the utility costs the credit is intended to avoid. On cross he testified, “The consumer price index has very little relationship with utility rates,” and warned that an above‑cost credit would shift costs into the Renewable Energy Standard Adjustment (RESA) and onto other customers: “If you're giving a larger credit, then you're departing from what the costs are… those costs get flow through the RESA, and the other customers have to pay for that.” The record shows Black Hills’ current RESA recovery is set at 1.5%; the statutory cap is 2%.

Interveners advocated a CPI‑U escalator to preserve subscribers’ buying power if they select a fixed credit. Blake Elder of the Coalition for Community Solar Access filed a CPI‑based spreadsheet and, during the hearing, identified and corrected an arithmetic error in his exhibit; he said the correction did not change the substance of the joint parties’ recommendation. Joint parties’ discovery responses and corrected attachment spreadsheets display the CPI‑U percent adjustments that would apply to historical vintages.

Staff and Black Hills also debated timing and legal interpretation: staff noted the PUC rulemaking order implementing HB23‑1137 left the tariff filing process as the venue to consider how to address changes in fixed credit value; Black Hills argued its TAR‑based annual calculation better tracks avoided costs. No final methodological choice was made at the hearing.

The judge directed parties to file statements of position by June 10, 2025; parties indicated willingness to consider a smoothing compromise if ordered by the commission.