Peak sun hours in Hawaii
Hawaii averages 5.6 peak sun hours a day across the year, 5th of the 50 states. At that figure a 400-watt panel produces about 1.72 kWh a day after real-world losses, and covering the 900 kWh average US bill takes about 18 panels. Honolulu, the state's biggest city, runs slightly ahead of the statewide figure at 5.7 hours; treat 5.6 as the midpoint of a real spread rather than a local reading.
strong sun: 5.6 of a possible ~6.5 hours
Panel counts for Hawaii bills
Computed at Hawaii's 5.6 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 | Hawaii | System size | US average |
|---|---|---|---|
| 500 kWh/mo | 10 panels | 4 kW | 12 panels |
| 750 kWh/mo | 15 panels | 6 kW | 18 panels |
| 900 kWh/mo | 18 panels | 7.2 kW | 22 panels |
| 1,000 kWh/mo | 20 panels | 8 kW | 24 panels |
| 1,500 kWh/mo | 29 panels | 11.6 kW | 36 panels |
| 2,000 kWh/mo | 39 panels | 15.6 kW | 48 panels |
What 5.6 hours means in practice
Hawaii sits in the strong tier of American sun, 5th of 50 at 5.6 hours, 24% above the national average. In panel terms the 900 kWh average bill needs 18 panels here instead of the US-average 22. Systems this far into the Sun Belt usually pencil on production alone; the variables that actually kill quotes here are shade and roof direction, not the resource.
How a Hawaii year is shaped
The 5.6-hour figure is an annual average, and no month is average. These are the twelve monthly means for Hawaii from NASA's 2001-2020 solar climatology, each as a share of the state's own annual mean, with that share applied to the 5.6-hour planning figure. June and December are marked.
| Month | Share of the annual average | Peak sun hours (est.) |
|---|---|---|
| January | 79% | 4.4 |
| February | 88% | 4.9 |
| March | 97% | 5.4 |
| April | 110% | 6.2 |
| May | 117% | 6.6 |
| June | 120% | 6.7 |
| July | 120% | 6.7 |
| August | 116% | 6.5 |
| September | 108% | 6.1 |
| October | 93% | 5.2 |
| November | 79% | 4.4 |
| December | 72% | 4.0 |
Hawaii barely has a solar winter. December still returns 72% of the annual average and June only 120% of it, 1.7 to one between them, the flattest curve of the fifty states; the four best months hold 39% of the year, which is close to the 33% a perfectly even year would give. Sizing here is a question of how much roof you want to cover, not which month will starve the battery.
Half the Hawaii calendar sits above the annual average and half below: April through September are the six months that beat it, carrying 58% of the year's light. April is already worth about 6.2 hours a day, so the productive half of the year starts earlier than most people expect.
Bills here are small, which changes the shape of the whole decision: EIA put the average Hawaii household at 495 kWh a month in 2024, 43% under the national 863 and among the lowest in the country. 10 panels cover it across a year, and 14 would be needed to cover it from December sun alone, 1.4 times as many. That is a narrow enough gap that storage sized for a Hawaii December is an ordinary purchase rather than a project-killer, which is not true in most of the country.
Hawaii is more uniform than most. The 4 grid cells sampled across the state span 10%, sunniest in the centre and dimmest in the southeast, which scales to about 5.9 hours against 5.3. Enough to notice on a production estimate, not enough to change which system you buy. Honolulu sits inside that band, not at the edge of it.
What that sun is worth on a Hawaii bill
| EIA, 2024 residential averages | Hawaii | United States |
|---|---|---|
| Average home's monthly use | 495 kWh | 863 kWh |
| Price per kilowatt-hour | 42.86¢ | 16.48¢ |
| Average monthly bill | $212.12 | $142.26 |
| One 400W panel, a year's output | 630 kWh | 506 kWh |
| What that output displaces | $270 | $83 |
Power is expensive here, and that is most of the story. At 42.86¢ a kilowatt-hour Hawaii was the 1st dearest state in 2024, 160% above the national 16.48¢, so every kWh a panel makes is worth 160% more than the same kWh in an average state. One 400-watt panel offsets about $270 of Hawaii electricity a year against $83 at national sun and national prices. Expensive power is the strongest argument for solar there is.
Rank Hawaii by what a panel earns rather than by sunlight and it moves up 4 places, from 5th to 1st. Rates do that. Utah gets less sun (5.5 hours to Hawaii's 5.6) and pays 12.22¢ against 42.86¢, so one panel is worth about $194 more a year in Hawaii than in Utah.
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; 42.86¢ is every Hawaii 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 Hawaii?
About 18 400-watt panels (7.2 kW) for the 900 kWh a month an average US home uses, at Hawaii's 5.6 peak sun hours. For the average Hawaii home specifically, which EIA measured at 495 kWh a month in 2024, it is 10. Your own bill is the variable that matters, and the calculator takes any figure.
Is 5.6 peak sun hours good for solar?
Yes, comfortably. Hawaii ranks 5th of the 50 states, 24% above the national average, which means fewer panels per kWh of bill than almost anywhere else in the country.
How much is one solar panel worth a year in Hawaii?
About $270. One 400-watt panel at Hawaii's 5.6 peak sun hours makes roughly 630 kWh a year after the 0.77 derate, and Hawaii residential electricity averaged 42.86¢ a kilowatt-hour in 2024 (EIA), which puts Hawaii 1st of the 50 states on this measure against 5th 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 Hawaii?
Yes, by a factor of 1.7 here. NASA's 2001-2020 climatology puts Hawaii's June at 120% of the annual average and December at 72%, so the 5.6-hour figure on this page is the midpoint of a curve running from roughly 6.7 hours a day down to 4.0. Grid-tied homes bank the summer surplus as credit; off-grid designs have to size for the trough, and in Hawaii that means 14 panels for an average local bill instead of 10.