Solar in Montana costs about $2.73 per watt, so the typical 7.13 kW system runs about $19,465 before incentives. Netting is full retail, but once a year, on a true-up date you choose, any unused credits go to your utility for nothing, so that date shapes how big your system should be.
Size a system around your true-up date
In Montana, the right system depends on which date your credits reset. Enter your ZIP code and we size to your true-up date, not a generic year.
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April 1 or October 1: one box on the Montana paperwork sets what you keep
Once a year, on the date you designate as the start of your 12-month billing period, Montana hands any unused solar credits from the past 12 months to your utility. You are paid nothing for them (MCA 69-8-603(4)). It is not a penalty. It is the ordinary annual true-up. You pick one of four dates, and each one catches a different amount in the bank.
Roughly half the summer surplus is still unspent ahead of the coldest months. Winter would have used those credits.
The year’s low point, drained by a winter of heating. Little is left to surrender.
The spring build-up, just as peak production starts. The early-summer bank goes back to the utility.
The entire summer surplus. The bank is fullest right before winter needs it.
Verdicts are for a heating-heavy home. Same house, same panels: on October 1 it gives up its whole summer bank just before the season it was saved for. On April 1 it gives up almost nothing, because winter has already spent the credits.
Pick the date before you signThe designation is one box on the interconnection paperwork. Ask your installer which date they entered, and why.
Retail credit all month, every month, until the reset
Most of the Montana deal is generous. The reset is the one catch.
Within each month
You net at your utility’s full retail rate, modeled here at the statewide average, one-to-one on systems up to 50 kW. A surplus carries forward as kilowatt-hour credits, not as a marked-down cash figure. That is better than most states now offer.
On your true-up date
Credits still unused from the previous 12 months go to the utility without compensation, on January 1, April 1, July 1 or October 1, whichever you chose.
Co-op members: check your own rules firstThe statute covers NorthWestern Energy and Montana-Dakota Utilities. Electric cooperatives set their own terms. If your power comes from a co-op, the 50 kW ceiling and retail netting are not automatically yours.
NorthWestern tried to end retail netting in 2019, and lost
In December 2019 the Public Service Commission rejected NorthWestern Energy’s bid to end retail-rate net metering and move solar customers into a separate rate class. Retail netting survived. That is why Montana still offers a deal that Nevada, Kentucky and others have moved away from.
These terms are a policy position, and policy can change. Flathead, Yellowstone Valley and the other co-ops write their own rules, so confirm yours before you model anything.
$2.73 a watt on small Montana systems, 5 kW to 10 kW
At $2.73 per watt, Montana sits 11th lowest of 51, $0.16 under the $2.89 national figure. The typical system is 7.13 kW, the median size Montana homeowners installed in 2025 (Berkeley Lab, 599 systems), at about $19,465. It makes roughly 10,043 kWh a year. That context matters where median home values run to $425,400 and roofs are often steep metal. Wondering how that compares? See our state-by-state solar pricing.
Gross, before incentives, at Montana’s $2.73 per watt benchmark. Real quotes vary by roof, equipment and installer.
10,043 kWh at 13.84¢: how a 7.13 kW Montana system reaches 14.0 years
No subsidy arrives to fix a badly sized system. Montana’s one break: up to $20,000 of the system’s value is exempt from property tax for 10 years. The whole weight sits on getting the true-up logic right.
7.13 kW at $2.73 per watt, all output used at home
The 13.84¢ is a statewide average for ranking, not a billed rate. NorthWestern Energy files its own residential rate, so rerun the year and the payback with the rate on your own bill.
A 30¢ premium costs more than a yearOn a 7.13 kW system, a quote 30¢ per watt above $2.73 adds about $2,139. That is over a year and a half of savings at $1,390 a year.
Four Montana buyers the annual reset works against
The true-up turns a sound deal into a poor one in these cases:
- Anyone sold a system sized to annual usage. A yearly total hides the months when credits pile up and then reset. Ask for output and use by month, and look hard at May and June.
- Cabin and seasonal-property owners. A property occupied in winter and empty in summer is the worst possible match for a July 1 true-up.
- Co-op customers who assume the statute covers them. It does not. Flathead, Yellowstone Valley and the others write their own rules.
- Anyone quoted well above $2.73 per watt. On a 7.13 kW system, a 30¢ premium is about $2,139 and adds well over a year to the payback.
Get Montana quotes built month by month
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More on Montana solar costs
Frequently asked questions
How much do solar panels cost in Montana in 2026?
About $2.73 per watt installed, 11th lowest of 51 in the EcoGen Solar Cost Index (September 2026 Edition). The typical system is 7.13 kW, the median size Montana homeowners installed in 2025, roughly $19,465 before incentives.
Does Montana have net metering?
Yes, full retail one-to-one for systems up to 50 kW on NorthWestern Energy and Montana-Dakota Utilities, under MCA Title 69 chapter 8 part 6. Surplus carries forward as kilowatt-hour credits rather than a cash figure, which is better than most states now offer. Cooperatives are not covered and set their own terms.
When do Montana solar credits expire?
At your annual true-up, on whichever of January 1, April 1, July 1 or October 1 you designate as the start of your 12-month billing period, when credits unused from the previous 12 months are granted to the utility without compensation under MCA 69-8-603. October 1 is the costliest designation for a heating-heavy home, because it surrenders the whole summer bank right before winter would have used it; April 1 is usually the right pick.
What is the solar payback period in Montana?
About 14.0 years in the best case, if every kWh the 7.13 kW system makes replaces power at the 13.84¢ state average. Sizing matters more than usual: a system built to cover winter will bank credits through spring that a poorly chosen true-up date then removes, so a smaller, better-matched system often pays back faster than a larger one.
Is Montana net metering going to change?
Nothing is currently pending. NorthWestern Energy asked the Public Service Commission to end retail-rate net metering and create a separate solar rate class, and the commission rejected that in December 2019. Retail netting survived and no successor proceeding or closing deadline is on file, though the history is a reminder that these terms are a policy decision.
How we calculate these costs
Cost figures use Montana’s entry in the EcoGen Solar Cost Index (September 2026 Edition), $2.73 per watt, 11th lowest of 51. The 7.13 kW typical size is Berkeley Lab’s 2025 median for Montana single-family installs (599 systems). Best-case payback divides the typical system’s cost by a year of its output (10,043 kWh) valued at the 13.84¢ state average (EIA 12-month residential average, August 2025 to July 2026), with no federal residential credit for owner-purchased systems and no credits lost at the true-up. Cooperative territories are excluded from the statutory terms described.
Sources (7)
- Montana Legislature, Montana Code Annotated 69-8-603 (read August 18, 2026): mca.legmt.gov
- NorthWestern Energy, Home Solar and Net Metering Information: northwesternenergy.com
- Montana Public Service Commission, December 2019 Order on NorthWestern Solar Class Proposal: psc.mt.gov
- U.S. EIA, Electric Power Monthly, residential price by state, 12-month average August 2025 to July 2026: eia.gov
- U.S. EIA, Form EIA-861: Annual Electric Power Industry Report, 2024: eia.gov
- U.S. Census Bureau, American Community Survey, 2024: census.gov
- IRS, One, Big, Beautiful Bill Provisions (Public Law 119-21): irs.gov
