How Many Solar Sun Hours Does Your State Really Get?
- ifeoluwa Daniel
- 4 hours ago
- 10 min read
Alaska gets more summer sunlight than Florida, up to 22 hours of daylight in June. Yet Alaska ranks near the bottom for solar ROI while Florida thrives in the top 10. Michigan receives the same annual sunlight as Germany (which leads Europe in solar capacity), but Michigan homeowners see 9-11 year paybacks while German systems pay back in 8-10 years.
See, here is the thing: sunlight hours matter, but they're not the determining factor for whether solar makes financial sense. A state with 4 peak sun hours and high electricity rates will outperform a state with 6 peak sun hours and cheap power every single time. That's a solid fact!
If you continue with me in this comprehensive guide, you'll learn what the average sunlight hours for all 50 states actually mean for solar production, and show you exactly how sunlight translates to real savings and payback periods.
Key Takeaways
Peak sun hours (PSH) measure the equivalent hours of full-intensity sunlight (1,000 W/m²), not total daylight hours
U.S. states range from 3-7 peak sun hours daily, with most falling between 4-6 hours
A difference of 2 peak sun hours (4 vs. 6) only reduces annual production by ~33%, not the 50% most people assume
States with 3.5-4 PSH (Pennsylvania, New York, Ohio) can deliver better ROI than 6+ PSH states due to electricity rates and incentives
Solar becomes financially viable at just 3 peak sun hours when combined with favorable state policies and net metering
What Are Peak Sun Hours (And Why Total Daylight Doesn't Matter)
Peak sun hours (PSH) aren't the same as "hours of sunlight" in a day. They represent the equivalent hours of full-intensity solar radiation at 1,000 watts per square meter—the standard testing condition for solar panels.
Here's how it works: When the sun rises at 7 AM and sets at 7 PM (12 hours of daylight), you don't get 12 peak sun hours. Early morning and late evening sunlight is weak, maybe 200-400 watts per square meter. Mid-day sun is strongest at 900-1,000 watts per square meter. Peak sun hours add up all that varying intensity and convert it to equivalent full-power hours.
Example:
2 hours at 200 W/m² = 0.4 PSH
3 hours at 500 W/m² = 1.5 PSH
4 hours at 1,000 W/m² = 4.0 PSH
3 hours at 500 W/m² = 1.5 PSH
2 hours at 200 W/m² = 0.4 PSH
Total: 11.8 PSH from 14 hours of actual daylight
This is why Alaska's 22 hours of summer daylight doesn't translate to 22 peak sun hours—the sun angle is too low, and intensity rarely reaches 1,000 W/m². Meanwhile, Arizona's 10-11 hours of daylight in summer deliver 7+ peak sun hours because of the sun's high angle and clear skies.
For solar planning, peak sun hours are the only number that matters. They directly determine your annual energy production.
Average Peak Sun Hours by State: Complete Rankings
Here's the comprehensive data for all 50 states, ranked by annual average peak sun hours:
Top 10 States for Peak Sun Hours
Middle 30 States (Moderate Sunlight)
Bottom 10 States for Peak Sun Hours
*Hawaii ranks high for sunlight, but separately due to island's geography
Deep Dive: IntegrateSun Service States
Here's detailed sunlight data for the 12 states where IntegrateSun operates, including how sunlight hours translate to real financial performance:
IntegrateSun States: Sunlight Hours & Solar Performance
Key Insight:Â Washington DC has the same sunlight as Maryland (4.0-4.5 PSH) but achieves dramatically faster payback (3.7-6 years vs. 6-11 years) due to its exceptional SREC program, adding $2,600+ annually. Meanwhile, Arizona produces 50% more electricity than Pennsylvania, but only marginally better payback due to Pennsylvania's higher rates and SREC income.
How Much Sun Do You Actually Need for Solar?
The minimum viable sunlight for solar profitability is approximately 3 peak sun hours daily. Below this threshold, systems struggle to generate enough electricity to justify installation costs, even with strong incentives.
Production by Sunlight Tier
Some Practical Examples:
Washington State (3.0-4.0 PSH):
Low sunlight BUT high electricity rates (12-14¢/kWh) + net metering at retail rates
Result: 9-12 year payback—acceptable but not amazing
Pennsylvania (3.5-4.5 PSH):
Low sunlight BUT SREC income (~$31.25 each) + high rates (13-15¢/kWh)
Result: 8-12 year payback—competitive with sunnier states
Oklahoma (4.5-5.5 PSH):
Moderate sunlight BUT low rates (10-12¢/kWh) + limited net metering value
Result: 11-14 year payback—longer despite more sun than Pennsylvania
The pattern is clear: 3.5+ peak sun hours with favorable policies beats 5+ peak sun hours with poor policies every time.
Seasonal Sunlight Variation by Region
Peak sun hours aren't constant year-round. Seasonal variation affects system performance and battery sizing requirements:
Seasonal Peak Sun Hours: Regional Patterns
Impact on System Design:
Southwest/Mountain West:Â Consistent year-round production means smaller battery systems work well for backup
Northeast/Mid-Atlantic:Â Heavy winter production drops require larger battery capacity or grid dependence
Pacific Northwest:Â Extreme seasonal variation (4x difference) makes battery-only systems challenging
Annual averages hide this variation, but it matters for battery sizing and energy independence goals. A Pennsylvania homeowner targeting year-round off-grid operation needs 2-3x more battery capacity than an Arizona homeowner due to winter production drops.
Why More Sun Doesn't Always Mean Better Returns
Here's the counterintuitive reality: the five states with the most sunlight don't crack the top 10 for solar ROI. Here's why:
High-Sun States with Moderate ROI
Arizona (6.5-7.0 PSH, 6-7 year payback):
Excellent production (8,100-8,700 kWh annually)
BUT: Low electricity rates (12-13¢/kWh)
No SREC program
Result: Good but not exceptional returns
Nevada (6.0-6.5 PSH, 8-10 year payback):
Strong production (7,500-8,100 kWh annually)
BUT: Low rates (11-12¢/kWh) + reduced net metering (75% of retail)
No SREC program
Result: Longer payback than states with half the sunlight
Lower-Sun States with Exceptional ROI
Washington DCÂ (4.0-4.5 PSH, 3.7-6 year payback):
Moderate production (5,000-5,600 kWh annually)
BUT: SREC income of $2,600-$2,958 annually
Full retail net metering
Result: Fastest payback in the nation despite being #30 for sunlight
Maryland (4.0-4.5 PSH, 6-11 year payback):
Moderate production (5,000-5,600 kWh annually)
BUT: SREC income ~$384 annually + moderate rates (13-15¢/kWh)
Full retail net metering
Result: Competes with Nevada despite 35% less production
The lesson: Focus on total annual value (electricity savings + incentives), not just production.
Does Your State Have Enough Sun?
Use this decision framework to determine if solar makes sense in your state:
Solar Viability by State Characteristics
Bottom Line:Â If your state has 4+ peak sun hours, solar is almost certainly viable with the right system design and available incentives. If your state has 3.5-4 PSH, evaluate incentives and electricity rates carefully. Below 3.5 PSH, you need exceptional programs to make solar worthwhile.
Making the Right Decision for Your State
Average sunlight hours tell you how much electricity your solar panels will produce—but they don't tell you whether solar is a smart financial decision. Production matters, but it's just one variable in a complex equation.
States with 3.5-4 peak sun hours can deliver better returns than states with 6-7 peak sun hours when policies align. Washington DC proves this daily, achieving the nation's fastest payback despite ranking #30 for sunlight. Pennsylvania homeowners save more annually than Nevada homeowners despite producing 25% less electricity.
The key factors that actually determine solar ROI:
Electricity rates:Â Higher rates mean each kWh produced saves more money
State incentives:Â SRECs and rebates add thousands in annual value
Net metering policies:Â Full retail credit vs. reduced export rates changes long-term returns dramatically
Installation costs:Â Lower costs accelerate payback regardless of production
If you're researching whether your state gets "enough" sun, the answer is almost certainly yes—if your state has favorable solar policies. The real question is: what combination of production, rates, incentives, and policies delivers the strongest ROI for your specific situation?
Get a Custom Analysis for Your State and Home
IntegrateSun serves homeowners across 12 states with dramatically different sunlight profiles—from Arizona's 7+ peak sun hours to Pennsylvania's 3.5-4 peak sun hours. We've designed thousands of systems optimized for local conditions, electricity rates, and available incentive programs.
We'll provide:
Accurate production projections based on your roof orientation and local weather patterns
Analysis of your actual electricity rates and usage patterns
Complete breakdown of federal, state, and utility incentives
Realistic payback calculations accounting for all variables
System sizing optimized for your state's net metering rules
Schedule a Free Consultation to discuss solar viability in your specific state, and financial projections based on your home's location and characteristics.
Your state's sunlight hours are just the starting point. Let's figure out what solar can actually save you.
FAQs
How many peak sun hours does my state need for solar to be worth it?
Solar becomes financially viable at approximately 3 peak sun hours daily when combined with favorable policies and electricity rates above 12¢/kWh. States with 3.5-4 PSH (Pennsylvania, New York, Maryland) achieve 6-12 year paybacks with strong incentives like SREC programs. States with 4-5 PSH deliver solid returns even with moderate incentives and average rates. Above 5 PSH, solar is viable in virtually any policy environment. Focus less on minimum sunlight and more on total annual value—electricity savings plus incentives determine real ROI, not production alone.
Do cloudy states like Washington and Oregon get enough sun for solar?
Yes, but with qualifications. Washington (3.0-4.0 PSH) and Oregon (3.5-4.5 PSH) receive enough sunlight for viable solar systems when electricity rates are favorable (12-14¢/kWh in Washington) and net metering provides full retail credits. These states see 9-12 year paybacks—longer than sunny states but still profitable over 25+ year system lifespans. Germany, with weather comparable to Washington, leads Europe in solar capacity. The key is managing expectations: Pacific Northwest systems produce 30-40% less electricity than Southwest systems but still generate positive returns when policies support solar adoption.
How do seasonal sunlight changes affect solar production?
Seasonal variation significantly impacts production patterns but is already factored into annual average peak sun hours. Southwest states see relatively stable production (45% drop winter to summer) while Northeast and Pacific Northwest states experience dramatic seasonal swings (60-75% drops). This affects battery sizing for off-grid goals—Pennsylvania homeowners need 2-3x more battery capacity than Arizona homeowners for year-round energy independence. However, grid-tied systems with net metering handle seasonal variation easily, banking excess summer production as credits to offset lower winter production. Annual production averages remain accurate for financial planning.
Why does Washington DC have faster payback than Arizona despite less sun?
Washington DC's SREC (Solar Renewable Energy Certificate) program is the nation's strongest, with SRECs trading at $400-$455 each. A typical 5 kW system in DC generates 5-6 SRECs annually, adding $2,600-$2,958 in income beyond electricity savings. This SREC income provides total annual value of $3,500-$4,000 compared to Arizona's $1,100-$1,400 (electricity savings only). DC achieves 3.7-6 year payback despite 35% less production than Arizona and higher installation costs. Arizona lacks SREC programs and has lower electricity rates, demonstrating how policy incentives outweigh sunlight advantages in determining financial performance.
Should I avoid solar if my state is ranked low for sunlight hours?
Not necessarily. Several "low-sun" states deliver excellent solar ROI due to strong policies. Pennsylvania (#40 for sunlight, 3.5-4.5 PSH) achieves 8-12 year paybacks thanks to SREC income and 13-15¢/kWh electricity rates. Massachusetts (#42, 3.5-4.5 PSH) offers SREC programs and high rates yielding solid returns. Even Michigan and Wisconsin (bottom 10 for sun) can achieve acceptable paybacks with state incentives. Evaluate your state's complete solar landscape—electricity rates, incentives, and net metering policies—not just sunlight rankings. If your state has 3.5+ PSH plus favorable policies, solar likely makes financial sense regardless of national sunlight rankings.