Montana Solar Calculator

Montana offers net metering up to 50 kW — one of the highest limits nationally — plus an altitude UV boost for elevated communities. Enter your NorthWestern Energy bill to see your 30% ITC savings.

Your Montana solar inputs

Monthly electric bill?

Utility?

System size?

Battery backup?

Montana solar estimate

20 × 400W panels (8 kW system)

Recommended size for your bill: 9.0 kW

Monthly usage1,000 kWh/mo

Annual production (MT 4.5 PSH + altitude boost)10,932 kWh/yr

Annual savings (net metering up to 50kW)$1,312/yr

Gross system cost$22,800

Federal ITC (30%)-$6,840

Montana state tax creditNone available

Net cost after ITC$15,960

Property tax reduction (annual est.)$137/yr

Payback period12.2 yrs

25-year savings$32,797

Montana's 4% altitude UV boost (applied to efficiency) adds production above PSH average alone. Net metering limit of 50 kW is one of the highest in the nation. No state income tax credit available. Snow panel angle optimization recommended for Montana winters.

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How to Use This Calculator

Montana's unique solar advantage: altitude UV boost

Montana's solar resource is more favorable than the 4.5 PSH average suggests. At elevations of 3,000-5,500 feet, Montana's thinner atmosphere filters less UV radiation — solar panels receive more intense radiation per square meter than at sea level. This altitude UV boost adds approximately 4% to actual panel production compared to what PSH alone would calculate. Billings sits at 3,117 feet; Helena at 4,086 feet; Butte at 5,549 feet. Higher-elevation communities like Butte and Bozeman benefit most from this bonus, with production running 5-7% above pure PSH-based estimates.

Enter your bill and select your Montana utility

NorthWestern Energy is Montana's dominant utility, serving virtually all of the state's major cities: Billings, Missoula, Great Falls, Helena, Bozeman, Butte, and Kalispell. NorthWestern Energy offers net metering up to 50 kW — one of the most generous limits in the nation. Pacific Power serves limited areas of western Montana near the Idaho border. Rural electric cooperatives serve frontier Montana. Enter your monthly bill, select your utility, and choose your system size to see production estimates including the altitude UV boost.

Montana net metering: 50 kW limit is exceptional

Montana's 50 kW net metering limit is among the highest residential/small commercial limits in the United States. Most states limit residential net metering to 10-25 kW. Montana's generous limit means homeowners can install significantly larger systems — beneficial for properties with high energy use (electric heat, EV charging, well pumps) and for maximizing summer surplus to offset Montana's higher-consumption winters.

The Formula

Monthly kWh = Monthly Bill ÷ Electricity Rate Annual Production = System kW × 1000 × 4.5 PSH × 365 × 0.832 efficiency (incl. altitude boost) ÷ 1000 Self-consumed kWh = Annual Production × 0.65 Exported kWh = Annual Production − Self-consumed kWh Annual Savings = (Self-consumed + Exported) × Retail Rate (MT net metering up to 50kW) Gross Cost = System kW × 1000 × $2.85/W + Battery ($12,000 if added) ITC Credit = Gross Cost × 30% Net Cost = Gross Cost − ITC Payback = Net Cost ÷ Annual Savings Property Tax Reduction = System Cost × ~0.6% (preferential MT rate)

Montana averages 4.5 PSH with a 4% altitude UV boost applied (effective efficiency: 0.80 × 1.04 = 0.832). Billings in eastern Montana is the sunniest major city at approximately 4.7 PSH. Missoula averages 4.3 PSH due to valley inversions and more precipitation. Great Falls and Helena average 4.5-4.6 PSH. Montana's $2.85/W installation cost reflects a smaller but growing solar market with good equipment availability through regional suppliers.

Example

Dave — Billings NorthWestern Energy customer

Dave is in Billings on NorthWestern Energy paying $120/month at $0.12/kWh. He installs an 8 kW system to take advantage of Billings' eastern Montana sun and the altitude UV boost.

Monthly bill$120 (NorthWestern Energy, $0.12/kWh)

System8 kW, no battery

LocationBillings, MT (4.5 PSH avg + altitude boost)

Result

Annual production (4.5 PSH + 4% altitude boost)~9,737 kWh/yr

Annual savings (net metering)~$1,166/yr

Gross system cost~$22,800

Federal ITC (30%)-$6,840

Montana state creditNone

Net cost after ITC~$15,960

Property tax reduction (annual)~$137/yr

Payback period~13.7 years

25-year savings~$29,150

Dave's Montana system benefits from the altitude UV boost, producing about 9,737 kWh/year — roughly 400 kWh more than a sea-level equivalent system would in the same PSH conditions. Montana's net metering ensures full retail credit for all exported solar. The payback period is longer than higher-rate states, reflecting NorthWestern's $0.12/kWh rate. However, Montana's electricity rates are expected to rise as the state transitions away from coal — future rate increases will improve Dave's long-term savings. Snow panel mounting at steeper angles (35-45°) helps shed winter accumulation in Billings.

FAQ

Does Montana have net metering? ▼

Yes. Montana law (MCA 69-8-601 et seq.) requires NorthWestern Energy and other electric utilities to offer net metering for systems up to 50 kW. This is one of the highest net metering limits in the nation — most states cap residential net metering at 10-25 kW. Exported solar is credited at the retail rate. Credits carry forward monthly. At the end of a 12-month cycle, remaining credits may be compensated at a lower rate (check current NorthWestern Energy policy). The 50 kW limit accommodates large Montana homes with high electricity use for electric heat, well pumps, and EV charging.

What is the altitude UV boost for Montana solar? ▼

Montana's higher elevation means thinner atmosphere and less UV filtering. Solar panels at higher altitudes receive more intense solar radiation per square meter. Research shows approximately 1% production increase per 1,000 feet of elevation above sea level. Montana averages 3,000-5,000 feet, with communities like Butte (5,549 ft) and Bozeman (4,820 ft) at the high end. This altitude effect adds 3-5% to actual solar production above what PSH data alone suggests. This calculator applies a conservative 4% altitude boost to the system efficiency (0.80 × 1.04 = 0.832). The boost is most significant in Butte and Bozeman, and less impactful in lower-elevation areas like Billings (3,117 ft).

Does Montana have a property tax exemption for solar? ▼

Montana provides a property tax benefit for solar equipment through its Class 13 classification for renewable energy systems. Solar equipment is taxed at a preferential rate — significantly lower than standard personal property tax rates. The primary home value assessment is conducted normally, but the solar system equipment itself is assessed at the reduced Class 13 rate. The effective tax reduction varies by county and system size — this calculator estimates approximately $137/year in tax reduction for an 8 kW system. File for the classification with your county assessor after installation. This is not a complete exemption like Arkansas or Kansas, but provides meaningful ongoing tax savings.

Does Montana have a state solar tax credit? ▼

No. Montana does not currently offer a state income tax credit for residential solar installations. Montana did have a limited solar income tax credit historically, but it expired. The 30% federal ITC is the primary financial incentive for Montana homeowners. The 50 kW net metering policy, preferential property tax classification, and altitude UV boost round out Montana's solar package. Montana's relatively low $0.12/kWh electricity rate means longer payback periods — but NorthWestern Energy's rates are expected to rise as the utility transitions from coal to renewables and natural gas, improving long-term solar economics.

Is Montana a good state for solar? ▼

Montana is a moderate solar state with some unique advantages. The 4.5 PSH average is reasonable, and the altitude UV boost adds meaningful production in higher-elevation communities. The 50 kW net metering limit is exceptionally generous. The main challenges are low electricity rates ($0.12/kWh) and Montana's cold winters with potential snow cover — though steep panel mounting angles (35-45°) minimize snow impact. Billings and eastern Montana generally offer better solar conditions (more sun, less precipitation) than the rainier western valleys near Missoula and Libby. Montana's vast agricultural land and ranching properties also present excellent rural solar opportunities where electricity reliability is a primary concern.

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