Montana Solar Production & Irradiance Data
4.2 peak sun hours/day · 7,704 kWh/year from a 6kW system · near national average
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Montana receives an average of 4.2 peak sun hours per day, which translates to a Global Horizontal Irradiance (GHI) of 4.2 kWh/m²/day. When solar panels are tilted at the optimal angle for Montana's latitude, irradiance increases to 5.08 kWh/m²/day — a 21% boost over flat-mounted panels.
This puts Montana near the national average of 4.29 peak sun hours per day. Montana's solar resource is comparable to the national average, making solar a solid investment — especially with current incentive programs. These figures are derived from NREL solar resource maps and PVWatts reference calculations.
Expected Annual Output by System Size
| System Size | Annual Output | Avg Monthly | Annual Savings | 25-Year Savings |
|---|---|---|---|---|
| 4 kW (12-16 panels) | 5,136 kWh | 428 kWh | $667/yr | $16,675 |
| 6 kW (18-24 panels) | 7,704 kWh | 642 kWh | $1,000/yr | $25,000 |
| 8 kW (24-32 panels) | 10,272 kWh | 856 kWh | $1,333/yr | $33,325 |
| 10 kW (30-40 panels) | 12,840 kWh | 1,070 kWh | $1,667/yr | $41,675 |
Based on 5.08 kWh/m²/day tilt irradiance, 14% system losses, and 12.98¢/kWh electricity rate. Actual output varies by installation specifics.
Month-by-Month Solar Production in Montana
Estimated monthly output for a 6kW system:
Solar production in Montana peaks in June when a 6kW system generates approximately 1,002 kWh — about 13% of annual production in a single month. The lowest production month is December at approximately 270 kWh (3.5% of annual output). This 3.7:1 seasonal ratio is significant — battery storage or time-of-use rate plans can help smooth out this variation.
How Montana Compares Nationally
Tips for Maximizing Solar Production in Montana
Montana's 4.2 peak sun hours per day provides solid solar production. Proper panel orientation is important — aim for south-facing at Montana's latitude tilt angle for optimal year-round performance.
Snow management matters in Montana. Installing panels at a steeper tilt angle (35-45°) helps snow slide off naturally. Most modern panels are designed to shed snow quickly, and the cold temperatures actually improve panel efficiency — silicon solar cells produce more power in cold weather.
Consider adding battery storage to your Montana solar system. A 10-13 kWh home battery lets you store excess daytime production for evening use, maximizing your self-consumption and reducing grid dependence. This is especially valuable for backup power during outages.
Solar Irradiance Technical Data
Global Horizontal Irradiance (GHI): 4.2 kWh/m²/day. GHI measures the total solar radiation received on a horizontal surface, including direct sunlight and diffuse radiation from clouds and atmospheric scattering. This is the baseline measurement for solar resource assessment.
Tilt Irradiance: 5.08 kWh/m²/day. When panels are tilted at the optimal angle for Montana's latitude, they receive 21% more solar radiation than flat-mounted panels. This tilt optimization is one of the easiest ways to boost your system's output.
System Output Estimation: The annual production figures use the NREL PVWatts methodology: Tilt Irradiance × 365 days × System Size × (1 − System Losses) × Inverter Efficiency. We use 14% system losses (wiring, soiling, degradation, mismatch) and 96% inverter efficiency, matching PVWatts defaults.
Montana Solar Production FAQ
How many peak sun hours does Montana get?▼
Montana averages 4.2 peak sun hours per day, which is near the national average of 4.29 hours. Peak sun hours represent hours of full-intensity sunlight equivalent — a key factor in estimating solar panel output. This data is derived from NREL solar resource maps and PVWatts reference calculations.
How much electricity will a 6kW solar system produce in Montana?▼
A 6kW solar system in Montana produces approximately 7,704 kWh per year, or about 642 kWh per month on average. Production peaks in June (approximately 1,002 kWh) and is lowest in December (approximately 270 kWh). At Montana's average rate of 12.98¢/kWh, this saves you about $1,000/year.
What is the best month for solar production in Montana?▼
June is typically the best month for solar production in Montana, with a 6kW system producing approximately 1,002 kWh. The long daylight hours and high sun angle combine for maximum energy generation. The worst month is December, producing about 270 kWh — roughly 27% of the best month's output.
How does Montana's solar potential compare to other states?▼
Montana's average of 4.2 peak sun hours per day puts it near the national average of 4.29 hours. A 6kW system in Montana produces 7,704 kWh/year, compared to the national average of 7,562 kWh/year — that's +142 kWh/year (+2%). Even at Montana's 12.98¢/kWh rate, solar delivers solid returns.
What affects solar panel output in Montana?▼
Key factors affecting solar output in Montana include: roof orientation (south-facing is ideal), tilt angle (latitude tilt of 39° is optimal), shading from trees or buildings, panel efficiency rating, and local weather patterns. Montana's GHI (Global Horizontal Irradiance) is 4.2 kWh/m²/day, but panels tilted at the optimal angle receive 5.08 kWh/m²/day — a 21% improvement over flat-mounted panels.
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Montana Solar Data
- ☀️ Peak Sun Hours: 4.2 hrs/day
- 📊 GHI: 4.2 kWh/m²/day
- 📐 Tilt Irradiance: 5.08 kWh/m²/day
- ⚡ 6kW Output: 7,704 kWh/yr
- 📈 Best Month: June
- 📉 Worst Month: December
- 💡 Electricity Rate: 12.98¢/kWh
- 💰 Annual Savings (6kW): $1,000
- 📋 Data: NREL Reference Data