Is solar worth it in Montana in 2026?

How Montana pays for your solar power

Net metering at the retail rate. Montana law requires utilities to net solar of 50 kW or less against use each billing period, with surplus carried as kWh credits until a yearly settle-up, when leftover credits expire unpaid.

In the calculator, 40% of your solar output is used at home at the retail price and the rest is exported at about 100% of retail (our default for this kind of rule), so each solar kWh is worth 100% of the retail price on average. Change it if your utility pays more or less. Method

State or utility incentive	What it is worth
Montana renewable energy systems property tax exemption	Up to $20,000 of appraised value exempt from property tax for 10 years (single-family home)

How exports are credited

Montana sets net metering in state law, not in a utility tariff. Under MCA 69-8-103, a net metering system uses solar, wind or hydropower, sits on the customer’s premises and has a generating capacity of no more than 50 kilowatts. A typical home rooftop is far below that.

The rule in MCA 69-8-603 works in kilowatt-hours. If the utility supplies more electricity than the customer generates in a billing period, the customer pays for the net amount. If the customer generates more, the excess kilowatt-hours appear as a credit on the next bill. Because the credit is in kWh and is netted against use, exports offset usage at the full retail energy rate.

Credits do not last forever. The customer picks the start of a 12-month billing period (January 1, April 1, July 1 or October 1). At the end of that period, any unused credit goes to the utility “without any compensation to the customer-generator,” per MCA 69-8-603. NorthWestern Energy, the dominant utility, applies the same rule and lets customers choose January, April, July or October as the settle-up month. A customer can change it once with the utility’s one-time 12-month billing period change form.

NorthWestern also states that excess energy credits never offset non-energy charges such as basic service charges. Those stay on the bill even in a month when the system produces more than the home uses.

This page describes NorthWestern Energy territory. Co-op and municipal customers should ask their own utility how it applies the state rule. See net metering vs net billing for the general difference.

State incentives in 2026

• Property tax exemption. MCA 15-6-224 exempts up to $20,000 of appraised value on a single-family home for 10 years after a qualifying renewable energy system is installed. The statute lists no sunset date.

Montana’s old residential alternative energy income tax credit (MCA 15-32-201) was repealed in 2021 and is not available. No statewide residential solar rebate was confirmed.

The federal residential credit ended for systems installed after December 31, 2025. See what ended and what it means.

What it means for payback

Since exports earn retail energy value, there is little penalty for producing more than the home uses in a given month. That helps in Montana’s long, dark winters, because summer surplus can be banked and used later. The limit is the settle-up date: credits left unused at the end of the 12-month period are lost, so a system sized well above annual use wastes the extra.

A sensible target is annual production close to annual consumption, timed so the bank is low going into the settle-up month. Pick a settle-up month after the season when you draw down credits, not before the summer surplus is spent.

Fixed charges stay on the bill regardless of credits, so the savings come from the energy portion only. A battery adds little on credit value here, since exports already earn the retail energy rate. It matters mainly for backup power. See are solar batteries worth it.

Other rules worth knowing

• Size cap: 50 kW for net metering systems under state law.
• Interconnection: NorthWestern Energy handles small generator interconnection through Rules 16 and 17 of its Montana electric tariff, with separate request forms by level.
• Solar access: MCA 70-17-301 allows a solar easement to protect sun exposure, but it must be created in writing and recorded like other easements. It does not guarantee access without one.
• Other utilities: rural co-ops and municipal utilities may have their own paperwork and billing details. Ask before signing a contract.

Berkeley Lab does not publish a Montana median from enough systems, so the calculator starts from the U.S. median of $3.60/W. Put your own quote in.