Peak Sun Hours by State 2026: Full Ranking & What It Means
Peak sun hours range from 6.5 in Arizona to 3.2 in Alaska. See the full peak sun hours by state ranking and how it drives how many panels you need.
What peak sun hours mean
A peak sun hour (PSH) is one hour of sunlight at 1,000 W/m². Compressing a full day of variable sunshine into equivalent full-power hours lets you size solar simply: a 400W panel × 5 PSH × 0.8 derate ≈ 1.6 kWh/day. The US average is about 4.98 PSH/day.
State-by-state variation
Arizona leads at ~6.5 PSH (Phoenix), followed by Nevada, New Mexico, and Hawaii near 5.8–6.3. The Northeast (NY, MA, MI) runs 3.9–4.5, and Alaska bottoms out at ~3.2. This is why a 10,500 kWh home needs 13 panels in Arizona but 22 in Massachusetts.
Use it to size your system
Production per kW ≈ PSH × 365 × 0.8 derate. Multiply by your system kW to estimate annual kWh, then compare to your usage. The PVFig system size calculator does this automatically with your state's data.
FAQ
Which state has the most peak sun hours?
Arizona, around 6.5 PSH/day in Phoenix — the highest in the US (NREL PVWatts v8).
What are the peak sun hours in my state?
Use the PVFig system size calculator or the state guides — production per kW is shown for all 50 states with sources.
How many peak sun hours does the US average?
About 4.98 PSH/day nationwide.
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Sources
- U.S. EIA — electricity rates by state, eia.gov/electricity/monthly
- NREL PVWatts v8 — solar production by location, pvwatts.nrel.gov
- DSIRE — state incentives and net metering, dsireusa.org
- See how every figure on this page is calculated — PVFig methodology.
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