Rocky Mountain Power's Wyoming Solar True-Up: Why Leftover Credits Use Avoided Cost

If your Wyoming solar estimate multiplies every projected kilowatt-hour by the retail electricity price, look for its treatment of the annual surplus. Rocky Mountain Power's Schedule 135 has a separate rule for credits still unused when the calendar year turns.

Those credits are sold to the utility using an avoided-cost calculation. A homeowner reviewing disappointing savings should therefore distinguish electricity that offset bills during the year from credits left for the annual settlement.

What Schedule 135 does

The Wyoming tariff carries monthly net surplus forward as a kilowatt-hour credit while retaining applicable monthly charges. At the beginning of each calendar year, unused credits accumulated during the preceding year are sold using the applicable Schedule 37 avoided-cost calculation. Schedule 135 describes a weighted average of seasonal and time-period prices for the relevant technology. It does not promise the home's retail purchase price for the annual balance.

The retrieved tariff is effective for service on and after June 1, 2025. It covers qualifying customer-owned and operated facilities no larger than 25 kilowatts, intended primarily to offset the customer's own requirements. This article addresses that tariff, not every generator or utility in Wyoming.

Ask for two values in the savings model

Have the solar company identify how much production it expects to offset electricity purchases and how much it expects to remain at the annual settlement. Then ask which price it applies to each amount.

Suppose a hypothetical household ends the year with an unused credit balance. Valuing that entire balance at the household's retail energy price would not reproduce Schedule 135's settlement formula. The correction is to apply the relevant annual unused-credit price, not to assume all generation has no value.

Avoid using a single historical settlement price for the remaining life of a solar loan. Request scenarios showing how the result changes if the settlement value or household usage changes. Neither today's tariff nor a sales spreadsheet is a guarantee of future compensation.

Reconcile the settlement, not just the production app

Collect the final bills of the old calendar year and the first bills of the new one. Ask Rocky Mountain Power to identify the settled quantity, the applicable calendar year, the Schedule 37 price and where the credit or payment appears.

Compare those records with the proposal's annual forecast. A production app reports electricity generated by the system. It does not by itself show how much was consumed at home, credited on the utility bill or included in settlement. Keep the utility and inverter records separate until their measurement periods are reconciled.

If the numbers differ, ask a specific question. Was the model based on more household use? Did the installation begin partway through a year? Did it assume all surplus could offset a later winter bill even after the calendar reset? These are questions to test against records, not conclusions about wrongdoing.

Check the provider before applying the example

Wyoming's statutory framework addresses annual unused credits, but a provider's filed tariff supplies the implementation and pricing. Another utility's rate should not be substituted for Rocky Mountain Power's Schedule 37. The utility's current tariff index is the starting point for checking revisions.

If the corrected settlement calculation leaves a gap between the sales promise and your actual costs, bring the proposal, agreement and bills to Solar Exit's document review. Include the loan or lease schedule so the review can distinguish utility compensation from the payment obligation. A lower-than-expected settlement does not automatically cancel a contract.

General consumer information, not legal, tax or electrical advice. The applicable tariff, dates and agreement control individual circumstances.