Peak sun hours in New Hampshire
New Hampshire averages 3.9 peak sun hours a day across the year, 42nd of the 50 states. At that figure a 400-watt panel produces about 1.20 kWh a day after real-world losses, and covering the 900 kWh average US bill takes about 25 panels. Manchester, the state's biggest city, sits at 3.9 hours, close enough to the statewide figure to use either, though elevation and distance from water still move the number street by street.
modest sun: 3.9 of a possible ~6.5 hours
Panel counts for New Hampshire bills
Computed at New Hampshire's 3.9 hours with 400W panels and the 0.77 derate; the US-average column shows what the same bill takes at 4.5 hours, so you can see what your state's sun is worth in hardware.
| Monthly usage | New Hampshire | System size | US average |
|---|---|---|---|
| 500 kWh/mo | 14 panels | 5.6 kW | 12 panels |
| 750 kWh/mo | 21 panels | 8.4 kW | 18 panels |
| 900 kWh/mo | 25 panels | 10 kW | 22 panels |
| 1,000 kWh/mo | 28 panels | 11.2 kW | 24 panels |
| 1,500 kWh/mo | 42 panels | 16.8 kW | 36 panels |
| 2,000 kWh/mo | 55 panels | 22 kW | 48 panels |
What 3.9 hours means in practice
New Hampshire runs 13% below the national solar average, 42nd of 50 at 3.9 hours. That is workable sun, not bad sun: the 900 kWh bill takes 25 panels here versus 22 nationally, 3 more. Germany built the world's densest solar fleet on worse.
How a New Hampshire year is shaped
The 3.9-hour figure is an annual average, and no month is average. These are the twelve monthly means for New Hampshire from NASA's 2001-2020 solar climatology, each as a share of the state's own annual mean, with that share applied to the 3.9-hour planning figure. July and December are marked.
| Month | Share of the annual average | Peak sun hours (est.) |
|---|---|---|
| January | 45% | 1.7 |
| February | 68% | 2.6 |
| March | 98% | 3.8 |
| April | 125% | 4.9 |
| May | 142% | 5.5 |
| June | 153% | 6.0 |
| July | 158% | 6.2 |
| August | 141% | 5.5 |
| September | 114% | 4.4 |
| October | 71% | 2.8 |
| November | 48% | 1.9 |
| December | 35% | 1.4 |
New Hampshire's light is front-loaded into summer. July holds 158% of the annual average against December's 35%, 4.5 to one, and the four strongest months carry 50% of the year. Read across the table: 6.2 hours a day in July, about 1.4 in December. The annual average is honest arithmetic and thin planning, because most of the energy shows up in the months you need heating least.
Half the New Hampshire calendar sits above the annual average and half below: April through September are the six months that beat it, carrying 69% of the year's light. April is already worth about 4.9 hours a day, so the productive half of the year starts earlier than most people expect.
New Hampshire homes are light users by national standards, 619 kWh a month on EIA's 2024 average against 863 nationally, 28% below. That is only 17 panels at the annual figure, which is why modest arrays go a long way here. Carrying the same house through December on its own would take 49, 2.9 times more.
New Hampshire is more uniform than most. The 4 grid cells sampled across the state span 9%, sunniest in the south and dimmest in the north, which scales to about 4.1 hours against 3.7. Enough to notice on a production estimate, not enough to change which system you buy. Manchester sits inside that band, not at the edge of it.
What that sun is worth on a New Hampshire bill
| EIA, 2024 residential averages | New Hampshire | United States |
|---|---|---|
| Average home's monthly use | 619 kWh | 863 kWh |
| Price per kilowatt-hour | 23.4¢ | 16.48¢ |
| Average monthly bill | $144.87 | $142.26 |
| One 400W panel, a year's output | 438 kWh | 506 kWh |
| What that output displaces | $103 | $83 |
New Hampshire pays 23.4¢ a kilowatt-hour, 9th highest in the country and 42% over the national 16.48¢. A single 400-watt panel therefore displaces about $103 of electricity a year here. Prices above the national line do more for a solar case than an extra half hour of sun does, because the sun sets the numerator and the rate sets what it is worth.
Which is why the sun ranking undersells New Hampshire. It places 42nd of fifty for sunlight and 10th for what a panel actually earns, a jump of 32 places, and the second number is the one that shows up on a bill. Compare it with a state that gets similar sun: Washington gets less sun (3.8 hours to New Hampshire's 3.9) and pays 11.9¢ against 23.4¢, so one panel is worth about $52 more a year in New Hampshire than in Washington.
Two warnings on those dollar figures. They are displaced electricity and nothing else: no install cost, no incentive, no financing, and no assumption about how your utility settles a surplus, which is the single biggest unknown in the sum. And a state average hides the utility you are actually on; 23.4¢ is every New Hampshire residential customer averaged together, and neighbouring territories can differ by more than the gap between two states in the ranking.
Getting a number for your address
For a location-exact figure, run your address through NREL's free PVWatts; it uses measured weather for your grid cell and will also model roof tilt and direction, which statewide numbers cannot. Then compare its annual kWh against a quote's promise before you sign anything.
Questions people ask
How many solar panels do I need in New Hampshire?
About 25 400-watt panels (10 kW) for the 900 kWh a month an average US home uses, at New Hampshire's 3.9 peak sun hours. For the average New Hampshire home specifically, which EIA measured at 619 kWh a month in 2024, it is 17. Your own bill is the variable that matters, and the calculator takes any figure.
Is 3.9 peak sun hours good for solar?
It is below the 4.5-hour national average but far from disqualifying. Panel counts run about 15% higher here for the same bill, and the December trough measured above deserves respect in any off-grid plan. Grid-tied systems ride through it on net metering.
How much is one solar panel worth a year in New Hampshire?
About $103. One 400-watt panel at New Hampshire's 3.9 peak sun hours makes roughly 438 kWh a year after the 0.77 derate, and New Hampshire residential electricity averaged 23.4¢ a kilowatt-hour in 2024 (EIA), which puts New Hampshire 10th of the 50 states on this measure against 42nd on sunlight alone. That figure is displaced electricity only. It says nothing about install cost, incentives, or how your utility settles a surplus.
Do peak sun hours change with the seasons in New Hampshire?
Yes, by a factor of 4.5 here. NASA's 2001-2020 climatology puts New Hampshire's July at 158% of the annual average and December at 35%, so the 3.9-hour figure on this page is the midpoint of a curve running from roughly 6.2 hours a day down to 1.4. Grid-tied homes bank the summer surplus as credit; off-grid designs have to size for the trough, and in New Hampshire that means 49 panels for an average local bill instead of 17.