Montana still credits exported solar at the full retail rate, one-to-one, a deal its Public Service Commission defended while most of the region abandoned theirs. The rule that decides whether you actually keep that value hides in the paperwork: once a year, at your settle-up month, every unused credit resets to zero. The installers worth hiring here design around that reset, sizing near annual usage and timing the settle-up date for winter’s end, and the three below build that way in Montana every week.
OnSite Energy, Big Dog Solar and Purelight Power are the three vetted Montana installers in our network. Full retail netting makes Big Sky solar quietly strong, provided your installer sizes near annual usage and sets the settle-up month deliberately, so ask every bidder how their design handles the annual credit reset.
Our Top 3 Solar Companies in Montana
Each company below was verified on its own published record and a working website this week. Nobody buys a spot on this page.
OnSite Energy
The home-state pick: a Bozeman-founded design and installation firm with a second office in Missoula, 800+ Montana projects and roughly 13 MW installed, including some of the largest arrays in the state. Residential, commercial and storage work is all designed and built by its own Montana team, for Montana’s climate.
Big Dog Solar
Regional scale from Idaho hubs in Boise and Pocatello: 16,000+ solar and battery installations across the Mountain West over 18 years, with design and install teams kept in-house. The warranty covers the part Montana winters test hardest, 10 years on workmanship and on every roof penetration.
Purelight Power
By its own install count the leading operator in Montana among its markets, with engineering specs that read like Big Sky weather: 130 mph wind and 50 mph hail ratings on every build. Year-one production is guaranteed as sold, then 10 years of workmanship and 25 years of parts and production coverage carry the long tail.
Montana Solar Companies Compared
Company | Montana Presence | Years | Build Scale | Warranty Core |
|---|---|---|---|---|
OnSite Energy | Bozeman + Missoula offices | Since 2012 | 800+ MT projects, ~13 MW | Manufacturer equipment coverage |
Big Dog Solar | Serves MT from Idaho hubs | 18 | 16,000+ Mountain West installs | 10-yr workmanship + roof penetrations |
Purelight Power | Leading MT installer by own count | Multi-state | 130 mph wind / 50 mph hail spec | 25-yr parts & production |
The Settle-Up Month Is a Design Decision
NorthWestern Energy nets exports one-to-one at retail, and the PSC held that arrangement in place until rooftop solar reaches 5% of peak load, a threshold years away. What the law gives annually, it also deletes annually: at your settle-up month, unused credits zero out with no cash-out and no rollover. Two choices defuse the rule. Size the system near 100% of annual usage so little surplus survives to be deleted, and set the settle-up month at the end of heating season, when a winter of drawing down the summer bank has emptied it naturally. Co-op customers add a third step: get the co-op’s own tariff in writing, because not all of them mirror NorthWestern.
Your reset month is one form field at interconnection, and most installers never mention it. Enter your ZIP code and get the timing worked out before the paperwork.
Get your settle-up month working for you
Questions to Ask a Montana Solar Installer
How does your projection treat year-end surplus credits?
Who sets my settle-up month, and to what?
What snow-load rating does the mounting carry?
How close is the design to my actual annual usage?
If I am on a co-op, whose rules apply?
Red Flags in a Montana Solar Pitch
How We Rank Solar Companies
Rankings are built from what we can verify, never from who pays us. Five weighted factors:
Frequently Asked Questions
OnSite Energy, Big Dog Solar and Purelight Power are the strongest verified Montana installers in 2026: OnSite as the Bozeman-and-Missoula firm with 800+ in-state projects, Big Dog for Mountain West scale and a roof-penetration warranty, and Purelight for hail-rated engineering backed by a 25-year parts and production warranty.
Wind & Solar World, a Dakotas-and-Montana installer working since 2007, remains part of our wider network, but its website has been unavailable since July 2026 and we only rank companies whose current details we can verify directly. If that changes, the roster will be revisited.
Yes, once, at your annual settle-up month, whatever credits remain reset to zero without compensation. A system sized near annual usage with a settle-up date at winter’s end loses almost nothing to the rule; an oversized system with a summer reset date donates weeks of production. The details are in our Montana solar guide.
Weighing more than the Montana market? Our national solar company rankings show how every market we cover compares.
Before collecting bids, check Montana incentives, price against Montana solar costs, and read the full banking strategy in our Montana solar guide.
Distance decides service quality out here. Enter your ZIP code to find the crew closest to you.
Find the closest vetted Montana crew
Sources
References & Research Sources
EcoGen America reviewed Montana net-metering law, NorthWestern Energy’s tariff and the installers’ own published claims for this article, including direct verification of OnSite Energy’s current website. Sources were accessed August 8, 2026, unless another publication, release, effective, or update date is listed below.
- Montana net-metering law & PSC rulings. Retail-rate crediting held until 5% of peak load; annual credit reset mechanics. Accessed August 8, 2026.
- NorthWestern Energy. Net-metering tariff and settle-up provisions. Accessed August 8, 2026.
- OnSite Energy. Company site: Bozeman and Missoula operations, project count and capacity installed. Accessed August 8, 2026.
- Big Dog Solar. Company site: install count, hubs and warranty terms. Accessed August 8, 2026.
- Purelight Power. Company site: engineering specs, guarantees and coverage. Accessed August 8, 2026.
