Solar Energy in Seattle, Washington
Average Solar Resource
#12 nationally · #1 in Washington
Pop. 737,255
Seattle, Washington receives 5.00 kWh/m²/day of solar irradiance and 5.8 peak sun hours daily, representing average solar resources . A typical 5 kW residential solar system in Seattle produces approximately 8,468 kWh annually, potentially saving homeowners $906 per year on electricity bills. After the 30% federal Investment Tax Credit, a 5 kW system has an estimated payback period of 11.6 years, leaving roughly 13 years of profitable operation within a standard 25-year warranty. For maximum annual output in Seattle, panels should be tilted at approximately 48° and oriented true south (180° azimuth).
Solar Resource Summary
GHI vs. US national average (4.5 kWh/m²/day)
Average
0
7.5 kWh/m²/day
Monthly Solar Data
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| GHI (kWh/m²/d) | 3.8 | 4.4 | 5.1 | 5.8 | 6.4 | 6.7 | 6.6 | 6.1 | 5.4 | 4.6 | 4.1 | 3.6 | 5.0 |
| DNI (kWh/m²/d) | 4.2 | 4.8 | 5.5 | 6.2 | 6.8 | 7.1 | 7.0 | 6.5 | 5.8 | 5.0 | 4.5 | 4.0 | 5.5 |
Source: NREL (MOCK DATA). Monthly averages in kWh/m²/day and °C.
Solar Production Estimates for Seattle
5 kW Residential
Typical home system
8,468 kWh/yr
706 kWh/month avg
≈ $906/year savings
10 kW Residential
Large home system
16,936 kWh/yr
1,411 kWh/month avg
≈ $1,812/year savings
50 kW Commercial
Small commercial
84,680 kWh/yr
7,057 kWh/month avg
100 kW Commercial
Medium commercial
169,360 kWh/yr
14,113 kWh/month avg
Production estimates based on NREL solar resource data, 48° tilt, south-facing orientation, and 80% performance ratio.
Local Solar Conditions in Seattle
Solar production in Seattle is relatively consistent year-round, ranging from 3.6 to 6.7 kWh/m²/day across the seasons.
- Best Tilt Angle
- 48° (latitude-optimized)
- Best Azimuth
- 180° (true south)
- Coordinates
- 47.6062°N, -122.3321°
Financial Overview — Solar in Seattle
Solar is a sound investment in Seattle. A 11.6-year payback period is in line with the national average. With electricity rates likely to increase over time, actual payback may be shorter. Estimated annual savings from a 5 kW system: $906/year.
- Avg. Electricity Rate
- $0.107/kWh (WA avg)
- Est. Annual Savings (5 kW)
- $906/year
- Est. Payback Period
- 11.6 years (after 30% ITC)
- Federal ITC
- 30% of system cost
- Net Metering
- Available
Financial estimates assume a 5 kW system at $3,000/W installed ($15,000 pre-ITC, $10,500 after 30% credit).
Actual costs vary by installer and equipment. Consult a local solar installer for firm quotes.
Solar FAQ — Seattle, Washington
In Seattle, Washington, a 5 kW residential solar system produces approximately 8,468 kWh of electricity per year. A 10 kW system produces about 16,936 kWh annually. These estimates use 5.0 kWh/m²/day average solar irradiance and an 80% system performance ratio, accounting for real-world losses from wiring, inverter efficiency, and temperature. Actual output will vary based on your specific roof orientation, shading, and equipment.
Seattle receives an average Global Horizontal Irradiance (GHI) of 5.00 kWh/m²/day. This is 0.50 kWh/m²/day above the US national average of 4.5 kWh/m²/day, placing Seattle near the national average. GHI measures total solar energy incident on a horizontal surface and is the primary indicator of a location's solar resource quality.
Seattle, Washington receives an average of 5.8 peak sun hours per day. Peak sun hours represent the equivalent number of hours when solar irradiance equals 1,000 W/m² — the standard condition used to rate solar panel output. This means a 1 kW solar panel array in Seattle produces 5.8 kWh on a typical day. Seasonal variation is significant: summer months see peak sun hours 40–60% higher than winter months in most US locations.
Seattle is a average location for solar panels, with 5.00 kWh/m²/day solar irradiance — near the national average. It ranks #1 in Washington and #12 nationally for solar potential. With an estimated payback period of 11.6 years, solar installations in Seattle can be financially attractive, especially given Washington's electricity rates.
The optimal tilt angle for solar panels in Seattle is approximately 48°, which corresponds to the city's latitude. This angle maximizes annual energy production by ensuring panels receive the most direct sunlight averaged over the year. For maximum winter output, tilt panels at latitude + 15° (63°). For maximum summer output, use latitude − 15° (33°). Fixed south-facing panels at the latitude angle are the standard recommendation for residential systems in Seattle.
A 5 kW solar system in Seattle can save an estimated $906 per year on electricity bills, based on Seattle's average electricity rate of $0.107/kWh. Over a 25-year system lifetime, that represents $22,650 in total savings before accounting for electricity rate increases. After the 30% federal Investment Tax Credit, the net system cost of approximately $10,500 for a 5 kW system yields a payback period of 11.6 years.
Seattle ranks #1 in Washington for solar potential based on annual GHI. This means 0 cities have higher solar irradiance in the state. As a top-ranked solar location, Seattle offers particularly strong economics for solar installations.Browse other Washington cities on our Washington solar data page to compare locations.
For a typical home in Seattle using 1,000 kWh/month, a 5 kW solar system producing 706 kWh/month would offset approximately 71% of a typical household's electricity use. Most residential installations in similar climates range from 5 to 12 kW depending on energy consumption, roof size, and budget. Use SolarScope's Site Studio to get a personalized system size recommendation based on your specific address and energy bills.
Based on local solar irradiance and electricity rates, a 5 kW residential solar system in Seattle has an estimated payback period of 11.6 years. This calculation assumes a net system cost of $10,500 (after the 30% federal ITC) and annual savings of $906. Modern solar panels carry 25-year performance warranties, so systems in Seattle would operate profitably for roughly 13 years after payback. Electricity rate increases over time typically reduce the effective payback period.
Learn more:
Solar irradiance ·
Peak sun hours ·
GHI explained ·
Net metering ·
How solar analysis works
Get a Detailed Solar Analysis for Seattle
This page shows area-level averages. For your specific address — accounting for roof orientation, shading trees, and your utility rate — use SolarScope's AI-powered Site Studio.
Open Site Studio Community Data for WashingtonQuick Stats
- Annual GHI
- 5.0 kWh/m²/day
- Peak Sun Hours
- 5.8 h/day
- 5kW Production
- 8,468 kWh/yr
- Payback (5kW)
- 11.6 years
- Rank in Washington
- #1