Solar Panel Calculator for Billings, MT
Estimate the cost, savings and payback of solar panels in Billings, MT, using local NREL sunshine data, Montana prices and electricity rates.
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Billings gets about 4.76 peak sun hours a day on a south-facing roof, so each kW of panels makes about 1,344 kWh a year. That ranks #70 of the 111 cities on this site. Output peaks in Jul and is lowest in Dec.
Sunshine in Billings by month
What an 8 kW system makes in Billings
| Month | Sun hours a day | Output | Bill savings |
|---|---|---|---|
| Jan | 2.48 | 520 kWh | $73 |
| Feb | 3.36 | 624 kWh | $88 |
| Mar | 4.56 | 920 kWh | $130 |
| Apr | 5.24 | 992 kWh | $140 |
| May | 6.12 | 1,152 kWh | $163 |
| Jun | 6.85 | 1,208 kWh | $171 |
| Jul | 7.45 | 1,328 kWh | $188 |
| Aug | 6.71 | 1,216 kWh | $172 |
| Sep | 5.46 | 1,000 kWh | $141 |
| Oct | 4.02 | 800 kWh | $113 |
| Nov | 2.65 | 536 kWh | $76 |
| Dec | 2.18 | 464 kWh | $66 |
| Year | 4.76 | 10,752 kWh | $1,519 |
Savings at 14.13¢ per kWh (Montana average), with every kWh credited at that price.
Cost and payback by system size
At $2.54 per watt, the Montana average, before incentives.
| System | Cost | Year 1 savings | Payback | 25-yr gain |
|---|---|---|---|---|
| 4 kW | $10,160 | $760 | 13.8 yrs | $7,734 |
| 6 kW | $15,240 | $1,139 | 13.8 yrs | $11,601 |
| 8 kW | $20,320 | $1,519 | 13.8 yrs | $15,468 |
| 10 kW | $25,400 | $1,899 | 13.8 yrs | $19,334 |
| 12 kW | $30,480 | $2,279 | 13.8 yrs | $23,201 |
How many panels you need in Billings
| Monthly use | System | 400 W panels |
|---|---|---|
| 500 kWh | 4.46 kW | 12 |
| 750 kWh | 6.70 kW | 17 |
| 1,000 kWh | 8.93 kW | 23 |
| 1,500 kWh | 13.39 kW | 34 |
| 2,000 kWh | 17.86 kW | 45 |
Covering 100% of a year's use at 1,344 kWh per kW.
Common questions
Is solar worth it in Billings?
At local averages an 8 kW system costs about $20,320 before incentives, saves about $1,519 in its first year and pays back in about 13.8 years.
How many peak sun hours does Billings get?
About 4.76 a day over the year on a south-facing roof at 20°, from 2.2 in Dec to 7.5 in Jul, according to NREL's PVWatts model.
How much does a 1 kW solar system produce in Billings?
About 1,344 kWh a year, or 112 kWh a month on average.
Is there a federal solar tax credit?
Not for homeowners who buy their system. The 30% Residential Clean Energy Credit ended for systems installed after December 31, 2025.
Sources
- NREL PVWatts V8 API (south-facing, 20° tilt, 14% losses, typical-year weather): https://developer.nlr.gov/docs/solar/pvwatts/v8/
- EnergySage, Solar panel cost by state (updated November 6, 2026): https://www.energysage.com/local-data/solar-panel-cost/
- U.S. EIA, Electric Power Monthly, Table 5.6.B (residential price, Jan–Aug 2026): https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_b