A worked example: 8 kW in Montana
An 8 kW system — about 19 × 425-watt panels — at Montana's assumed installed cost of $2.55–$3.35 per watt runs roughly $20,400–$26,800 before incentives. At about 1,330 kWh of production per installed kW, it would generate around 10,640 kWh per year. Valuing self-consumed electricity at the assumed $0.12/kWh retail rate and exports conservatively, first-year savings land near $1,052 — a simple payback of roughly 19–25 years.
There is no federal tax credit in that math: the Section 25D residential credit ended for systems installed after December 31, 2025. State or utility incentives, where they exist, would shorten payback from here.
Average cost of solar panels in Montana by system size
Most Montana quotes land between 6 and 12 kW. At the state's assumed $2.55–$3.35 per watt, here is what each size costs to install, what it produces, and how long it takes to pay for itself on electricity savings alone — no incentives applied.
| System size | Panels | Installed cost | Annual production | Est. payback |
|---|---|---|---|---|
| 6 kW | 15 | $15,300–$20,100 | 7,980 kWh | 19–25 yrs |
| 8 kW | 19 | $20,400–$26,800 | 10,640 kWh | 19–25 yrs |
| 10 kW | 24 | $25,500–$33,500 | 13,300 kWh | 19–25 yrs |
| 12 kW | 29 | $30,600–$40,200 | 15,960 kWh | 19–25 yrs |
Size should follow your electricity usage, not a round number — these are reference points, not a recommendation. Note that cost per watt rises on smaller systems, because permitting, labor and the inverter do not shrink with the array.
What solar costs per kWh in Montana
Spread across a 25-year life, with 0.5%/yr panel degradation and no financing cost, solar electricity in Montana works out to roughly 8.1¢–10.7¢ per kilowatt-hour. The Montana retail rate this page assumes is 12.0¢. That gap — not the sticker price — is what determines whether solar pays here, and it is why a sunnier state with cheap electricity can be a worse investment than a cloudier one with expensive electricity. See how every state compares on cost per kWh.
Net metering and export rates in Montana
Montana requires net metering from NorthWestern Energy for systems up to 50 kW with retail-value credits and annual netting; co-ops set their own rules.
Export rules are worth reading as an incentive, because they set what every kilowatt-hour you do not use on site is worth — see how Montana compares with every other state on net metering.
Montana solar incentives
Montana’s state residential energy credit was repealed in 2021 tax reform. Property tax exemption for renewable systems remains.
The most valuable program is property tax exemption. With no federal credit for 2026 installs, state and utility programs are now the whole picture — see the full Montana incentives guide.
What changes a Montana solar quote?
Equipment, roof condition, electrical upgrades, permitting, labor, system size, batteries and financing can all change the installed price. Savings also depend on the specific utility rate, how much solar electricity the home uses directly, and what the utility pays for exports.
Frequently asked questions
What is the average cost of solar panels in Montana?
The average installed cost in Montana runs $2.55–$3.35 per watt before incentives, which puts a 6 kW system at $15,300–$20,100, an 8 kW at $20,400–$26,800, and a 10 kW at $25,500–$33,500. Spread over a 25-year life, that works out to about 8.1¢–10.7¢ per kilowatt-hour, against a Montana retail rate assumed at 12.0¢.
How much does it cost to install solar panels in Montana?
Installation is not priced separately — the $2.55–$3.35 per watt above is a turnkey figure covering panels, inverter, racking, labor, permitting and interconnection. What moves it most in MT is roof complexity, whether the main panel needs upgrading, and whether a battery is included. Expect a site visit to change any online estimate, including this one.
How much do solar panels cost in Montana?
Using an assumed installed cost of $2.55–$3.35 per watt, a typical 8 kW home system in Montana costs roughly $20,400–$26,800 before incentives. Smaller and larger systems scale roughly with size, though small systems cost more per watt.
Is solar worth it in Montana?
With Montana electricity around $0.12/kWh and production around 1,330 kWh per installed kW per year, an 8 kW system could save roughly $1,052 in year one, for a simple payback of about 19–25 years with no federal credit. Whether that is "worth it" depends on your rate plan, export compensation, roof, and how long you plan to stay in the home.
How many solar panels do I need in Montana?
It depends on your electricity usage, not your roof. At Montana's assumed 1,330 kWh per installed kW, a 6 kW system (about 15 panels at 425 watts) generates roughly 7,980 kWh a year, and a 10 kW system (about 24 panels) roughly 13,300 kWh. Compare that against your annual kWh from a utility bill — our calculator sizes it from your monthly bill in about a minute.
Does Montana have net metering?
Montana requires net metering from NorthWestern Energy for systems up to 50 kW with retail-value credits and annual netting; co-ops set their own rules.
What solar incentives does Montana offer in 2026?
Montana’s state residential energy credit was repealed in 2021 tax reform. Property tax exemption for renewable systems remains. Note that the federal Section 25D residential credit ended for systems installed after December 31, 2025, so state, local and utility programs are now the main incentives for purchased systems.
Is there still a federal solar tax credit in Montana?
No — the 30% federal residential clean energy credit (Section 25D) ended for systems installed after December 31, 2025 under the One Big Beautiful Bill Act. Leased or PPA systems may still benefit indirectly because the system owner can claim the commercial 48E credit through 2027.
Use this as a starting point
This page provides broad state assumptions, not a current market survey or binding quote. Before purchasing, verify applicable incentives, utility rules, installer licensing, warranties and financing terms.
Where these numbers come from
State assumptions are informed by public data and reviewed periodically (September 2026):