Dean has connected tens of thousands of homeowners with residential solar installers across all 50 states since 2021, and works directly with installers on pricing and financing.
Montana still credits solar output at full retail, monthly, and carries any surplus forward as kilowatt-hours instead of dollars. Both are good terms. Then once a year, on a designated date, whatever credit you have not used is handed to the utility with no payment at all. In a state with Montana’s seasonal swing, which of four dates applies to your account is worth real money, and almost nobody asks.
The Rules, and the One That Bites
Montana mechanic | Detail | Why it matters to you |
|---|---|---|
Who is covered | NorthWestern Energy and MDU; cooperatives set their own terms | If a cooperative bills you, none of this describes your account |
System limit | Up to 50 kW, on the premises, under 69-8-103 | Far above any household need |
Monthly netting | At full retail | Midday generation offsets evening use at full value |
Surplus carries as | Kilowatt-hours, not dollars | Banked energy keeps its value as prices rise |
Annual true-up | One of January 1, April 1, July 1 or October 1, under 69-8-603 | Unused credit goes to the utility uncompensated |
The fourth row is genuinely valuable and rarely explained. States that bank a dollar credit leave you holding a fixed sum against a rising price, which erodes quietly. Montana banks energy, so a kilowatt-hour saved in July is still a kilowatt-hour in January.
Montana is one answer of fifty; the nationwide worth-it breakdown holds the rest.
The fifth row is what takes it back.
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Why the Date Matters in Montana
Montana sits between roughly the 45th and 49th parallels. Output concentrates hard into summer, and household electricity use runs heaviest through a long, dark winter. That means a Montana solar account naturally builds a large credit balance across summer and draws it down through winter, which is exactly what carrying credits in kilowatt-hours is designed to support.
Now put a forfeiture date in the middle of that cycle. A true-up falling at the start of October wipes the bank you spent all summer building, immediately before the months you were building it for. A true-up in spring lets that same bank do its job first, and surrenders only what genuinely was not needed.
Under 69-8-603 the customer-generator designates which of the four dates starts the 12-month billing period. Ask your installer which date they are entering on the interconnection form before it is filed, and if a date is already on your account, ask NorthWestern or MDU whether it can be changed. For a home that heats in winter, April 1 leaves the least in the bank to surrender; October 1 leaves the most.
What It Costs You If the Timing Is Wrong
A typical Montana system is 7.25 kW at $20,375, producing roughly 10,223 kWh a year against household consumption of around 852 kWh a month. Every kilowatt-hour below is valued at Montana’s 13.2¢ statewide average residential rate, which is ranking context rather than a billed rate. NorthWestern Energy and MDU each file their own residential tariff, so rerun the top row with the rate on your own bill before you treat 15.1 years as yours.
What happens at your true-up | Annual value | Break-even |
|---|---|---|
Balance already drawn down, nothing forfeited | $1,349 | 15.1 years |
Roughly a tenth of annual output surrendered | $1,214 | 16.8 years |
Roughly a fifth surrendered | $1,079 | 18.9 years |
Methodology: figures use the EcoGen Solar Cost Index for Montana, $2.81 per watt as of March 1, 2026, with no federal residential credit for owner-purchased systems and full retail netting with annual forfeiture at the designated true-up date. Payback figures are simple payback before financing, rate escalation (the state five-year average is 2.61%) and degradation. The forfeiture shares in rows two and three are illustrative brackets, not measured Montana averages.
Four years of payback riding on a calendar date is an unusually large return on one phone call, and it is the single most actionable decision in a Montana solar purchase.
The Arrangement Has Already Survived a Challenge
Worth knowing when you are weighing a twenty-five year decision: NorthWestern Energy asked the Public Service Commission to end retail net metering and put solar customers into a separate rate class, and in December 2019 the Commission refused.
No closing deadline, successor tariff proceeding or pending change is on file. That does not make the arrangement permanent, and nobody should sell it to you as such, but it does mean Montana’s terms have been tested under pressure.
Where the Montana Numbers Break
- If a cooperative bills you and you have not asked its terms. Montana’s statute reaches NorthWestern and MDU. Cooperatives set their own, and the figures here will not describe your account. Where a co-op credits exports below retail, every figure here gets worse, not better, so get the export rate and the true-up rule in writing before you model anything.
- If the system is sized above your annual consumption. Surplus beyond a year’s use meets the true-up and is surrendered, so oversizing in Montana buys panels whose output is eventually given away.
- If snow sits on the array for long stretches. Winter output is already the weak half of a very seasonal year; a shallow pitch that holds snow makes it weaker.
- If you are moving within fifteen years. Fifteen years is the best case on this page, and the break-even moves toward nineteen if part of your bank is forfeited each year.
- If a quote shows a 30% federal credit. Section 25D is $0 for purchased systems whose installation is completed after December 31, 2025 under Public Law 119-21, and the figures above assume no credit at all. A company that owns the system under a lease or power purchase agreement may qualify for the separate Section 48E business credit under current deadlines, but Montana currently has no residential third-party providers, so for a Montana buyer the practical federal credit is zero.
Montana is a reasonable yes on decent terms that have held up under pressure, provided the system matches the household and the forfeiture date is not working against you. Our Montana incentives guide covers what the state offers, and the Montana installer list covers who works here. One line on the interconnection form, the true-up date, is worth more than any quote comparison.
Enter your ZIP code to see which Montana installers are quoting, then get the true-up date on the interconnection form in writing.
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Montana Solar FAQs
Are solar panels worth it in Montana?
A reasonable yes for a household staying put on NorthWestern or MDU, at a simple payback around 15.1 years at the 13.2¢ statewide average and with nothing forfeited at the true-up; your own utility’s tariff moves that figure in either direction. If a meaningful share of your credit is surrendered each year the figure moves toward 19 years. Montana nets monthly at full retail and carries surplus as kilowatt-hours instead of dollars, which are good terms; the annual forfeiture is what claws value back.
What happens to unused Montana solar credits?
Under MCA 69-8-603 they are granted to the utility at a designated annual true-up, with no compensation at all. The statute names four dates: January 1, April 1, July 1 and October 1. Because Montana output concentrates into summer while consumption runs heaviest in winter, a true-up in early October wipes the balance built for exactly the months it was meant to cover, while a spring date lets that balance do its job first.
Can I choose my Montana true-up date?
Yes. MCA 69-8-603 lets the customer-generator designate January 1, April 1, July 1 or October 1 as the start of the 12-month billing period. April 1 is usually the right pick for a heating-heavy home, because the year then ends on March 31 with the summer bank already spent. On our modeling the difference between the best and worst date is roughly four years of payback.
Is Montana net metering at risk?
It has already been challenged and survived. NorthWestern Energy asked the Public Service Commission to end retail net metering and place solar customers in a separate rate class, and in December 2019 the Commission refused. No closing deadline, successor tariff proceeding or pending change is on file. That does not make the arrangement permanent, but Montana’s terms have been tested under pressure.
Does Montana net metering cover cooperatives?
No. MCA Title 69 chapter 8 part 6 reaches NorthWestern Energy and MDU; cooperatives set their own terms. If a cooperative bills you, none of the figures on this page describe your account, and the only way to find out what applies is to ask your provider directly for its terms in writing, including what happens to unused credit and on what date.
References & Research Sources
EcoGen America reviewed Montana Code Annotated Title 69, chapter 8, part 6, including 69-8-103 for the 50 kW on-premises system limit and 69-8-603 for monthly netting at full retail, the carrying of surplus as kilowatt-hour credits, and the granting of unused credits to the utility without compensation at a designated annual true-up falling on January 1, April 1, July 1 or October 1; and NorthWestern Energy’s home solar pages. Section 69-8-603(4) begins the 12-month billing period on the date designated by the customer-generator. Coverage extends to NorthWestern Energy and MDU; cooperatives set their own terms and are outside it. The Public Service Commission rejected NorthWestern’s request to end retail net metering and create a separate solar customer class in December 2019, and no closing deadline or pending change is on file since. We also reviewed EIA Electric Power Monthly for the 13.2¢ residential price and the five-year growth rate of roughly 2.61% a year, and IRS guidance on the Public Law 119-21 termination of Section 25D. Output of 1,410 kWh per kilowatt per year, the 7.25 kW system size, the $20,375 installed cost and the 852 kWh monthly usage are EcoGen America figures, $2.81 per watt as of March 1, 2026. The payback figures are our own calculation and are simple payback before financing, rate escalation and degradation; the forfeiture shares in the second and third rows are illustrative brackets, not measured Montana averages. Sources accessed between June 10 and August 18, 2026.
