Solar panels in Great Falls, MT
Roofs in Great Falls get about 1,585 hours of usable sunlight a year — more than 62% of the cities we've measured. Here's what that means in cost, savings and payback, using real rooftop data rather than a national average.
Check your specific roof in Great Falls → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical Great Falls solar system costs
A 21-panel system (8.4 kW) is about right for an average Great Falls home using 10,800 kWh a year. It would produce roughly 11,317 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 4,311 | $6,384 | $522 | 12.2 yrs |
| 12 panels | 4.8 kW | 6,467 | $9,576 | $782 | 12.2 yrs |
| 16 panels | 6.4 kW | 8,622 | $12,768 | $1,043 | 12.2 yrs |
| 20 panels | 8 kW | 10,778 | $15,960 | $1,304 | 12.2 yrs |
| 26 panels | 10.4 kW | 14,011 | $20,748 | $1,404 | 14.8 yrs |
How we worked this out for Great Falls
Every number on this page comes from these seven steps. Nothing is a national average — the sunlight figure is measured from Great Falls rooftops.
| # | Step | Result |
|---|---|---|
| 1 | What one panel makes here 400W ÷ 1000 × 1,585 sun hrs × 0.85 system losses |
539 kWh/yr |
| 2 | Panels needed to cover typical usage 10,800 kWh ÷ 539 kWh per panel |
21 panels |
| 3 | System size 21 panels × 400W |
8.40 kW |
| 4 | Annual production 8.40 kW × 1,585 hrs × 0.85 |
11,317 kWh/yr |
| 5 | Installed cost 8,400 W × $2.85 per watt, then −30% federal credit |
$16,758 |
| 6 | Annual saving 3,780 kWh used as generated × 12.1¢ + 7,537 kWh exported × 12.1¢ |
$1,322/yr |
| 7 | Payback $16,758 ÷ $1,322 per year |
12.7 years |
Step 6 matters more than it looks. Only 33% of what a system this size produces in Great Falls is used the moment it is generated; the other 7,537 kWh is exported and credited one-for-one under net metering. Because exports here are credited at or near retail, that split changes the payback very little — 12.2 years against the 12.7 we show. In places where exports pay a fraction of retail the same split moves payback by years, which is why we model it explicitly rather than assuming.
Assumptions: 400W panels, 15% system losses (inverter, wiring, heat, soiling), $2.85/W installed, 10,800 kWh typical annual household use, 12.1¢/kWh electricity. Change any of those and every figure above moves — which is exactly why a single national "solar costs X" number is misleading.
Notice that payback barely improves as systems get bigger, and eventually gets worse. That's because you can only save money on electricity you were going to buy anyway. Once a system covers your usage, extra panels mostly generate exports at a much lower rate.
Why Great Falls gets 1,585 sun hours
That figure comes from Google's analysis of real rooftops across Great Falls — it already accounts for shading from trees, chimneys and neighbouring buildings, which is why it's lower than the raw "hours of daylight" figures you'll see elsewhere. An unusually open, unshaded roof in Great Falls reaches about 1,611 hours, roughly 2% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,585 hrs/yr |
|---|---|
| Unshaded roof | 1,611 hrs/yr |
| Electricity rate (Montana avg) | 12.1¢/kWh |
| Installed cost assumed | $2.85/W |
| Panel size assumed | 400 W |
| Federal tax credit | 30% |
| Typical household usage | 10,800 kWh/yr |
| Power used as generated | 33% |
| Paid for exported power | full retail (net metering) |
| Rooftops sampled here | 10 |
| Google imagery from | 2012 |
When Great Falls actually produces
Annual totals hide the thing that catches people out: 40% of Great Falls's yearly sunlight arrives in May–July, and just 10% across November–January.
| Month | Sun hrs | Share of year |
|---|---|---|
| Jan | 55 | |
| Feb | 84 | |
| Mar | 124 | |
| Apr | 168 | |
| May | 202 | |
| Jun | 217 | |
| Jul | 209 | |
| Aug | 181 | |
| Sep | 140 | |
| Oct | 95 | |
| Nov | 62 | |
| Dec | 48 |
That is a severe seasonal swing — Great Falls produces roughly 4.5× as much in Jun as in Dec. A system sized to cover your annual usage will overproduce badly in summer and fall well short in winter, so how your utility credits exported power matters more here than in most places.
The annual total is measured from Google's rooftop imagery. Its split across months is calculated from solar geometry at Great Falls's latitude, not separately measured, so treat the monthly figures as the shape of a typical year rather than a forecast.
How Great Falls compares to the other 788 cities
| Measure | Great Falls | Rank of 788 |
|---|---|---|
| Usable sunlight | 1,585 hrs | 297th |
| Sunlight lost to shade | 2% | 741st most |
| Median roof size | 280 m² | 156th largest |
| Electricity rate | 12.1¢ | 703rd highest |
| Payback | 12.7 yrs | 619th fastest |
| Grid carbon | 696 kg/MWh | 233rd dirtiest |
What actually stands out about Great Falls:
- Unusually open roofs. Only 2% of available sunlight is lost to obstruction in Great Falls — better than all but 47 of the 788 cities measured. Most roofs here get close to their theoretical maximum.
- Plenty of roof to work with. Typical roofs here fit around 89 panels — roughly 4× what an average home needs. Roof size will not be what limits your system in Great Falls.
- Sunnier than the rest of Montana. Great Falls roofs get 6% more usable sunlight than the typical Montana city we've measured — statewide averages will understate what you can expect here.
- Cheap electricity is the headwind. Montana power costs about 12.1¢/kWh. Low rates are good news generally, but they lengthen solar payback — there is simply less bill to displace.
- Older imagery. Google's aerial capture of Great Falls dates from 2012. Tree growth and new construction since then are not reflected.
Cities with almost the same sunlight
These are the closest matches to Great Falls's 1,585 usable sun hours from other states and provinces. Same sunlight, different electricity prices — which is usually what decides whether solar is worth it.
| City | Sun hrs | Rate | Payback |
|---|---|---|---|
| Roswell, GA | 1,584 | 14.1¢ | 10.9 yrs |
| Portsmouth, VA | 1,584 | 14.2¢ | 10.8 yrs |
| Cape Girardeau, MO | 1,586 | 12.2¢ | 12.6 yrs |
| Kennewick, WA | 1,583 | 11.3¢ | 13.6 yrs |
Nearby cities
See all of Montana → statewide sunlight, rates, incentives and every city we've measured.
Great Falls solar questions
How many solar panels do I need in Great Falls?
About 21 panels for an average home using 10,800 kWh a year. Great Falls roofs get 1,585 usable sun hours, so each 400W panel produces roughly 539 kWh annually. A typical Great Falls roof fits about 89 panels, so roof space is unlikely to be your limit.
Is solar worth it in Great Falls?
At 12.1¢/kWh and 1,585 sun hours, a typical system pays for itself in about 12.7 years and returns roughly $16,303 over a 25-year panel life. That is slower than average, so compare several quotes before committing. Exported power earns full retail credit here.
How much do solar panels cost in Great Falls?
A 8.4 kW system costs about $23,940 before incentives and $16,758 after the 30% federal tax credit. That works out near $2.85 per watt installed. Roof pitch, shading, electrical panel upgrades and equipment choice move the price most, which is why quotes for the same house can differ by thousands.
Worth reading before you buy
Estimates only, generated 2026-08-22 from Google Solar API rooftop samples and average Montana electricity rates. Not a quote and not financial advice. Your roof, usage, utility plan and local incentives will change these numbers — get real quotes before buying.