Peak sun hours in Kentucky
Kentucky averages 4.3 peak sun hours a day across the year, 27th of the 50 states. At that figure a 400-watt panel produces about 1.32 kWh a day after real-world losses, and covering the 900 kWh average US bill takes about 23 panels. Louisville, the state's biggest city, sits at 4.3 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: 4.3 of a possible ~6.5 hours
Panel counts for Kentucky bills
Computed at Kentucky's 4.3 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 | Kentucky | System size | US average |
|---|---|---|---|
| 500 kWh/mo | 13 panels | 5.2 kW | 12 panels |
| 750 kWh/mo | 19 panels | 7.6 kW | 18 panels |
| 900 kWh/mo | 23 panels | 9.2 kW | 22 panels |
| 1,000 kWh/mo | 25 panels | 10 kW | 24 panels |
| 1,500 kWh/mo | 38 panels | 15.2 kW | 36 panels |
| 2,000 kWh/mo | 50 panels | 20 kW | 48 panels |
What 4.3 hours means in practice
Kentucky runs 4% below the national solar average, 27th of 50 at 4.3 hours. That is workable sun, not bad sun: the 900 kWh bill takes 23 panels here versus 22 nationally, 1 more. Germany built the world's densest solar fleet on worse.
How a Kentucky year is shaped
The 4.3-hour figure is an annual average, and no month is average. These are the twelve monthly means for Kentucky from NASA's 2001-2020 solar climatology, each as a share of the state's own annual mean, with that share applied to the 4.3-hour planning figure. June and December are marked.
| Month | Share of the annual average | Peak sun hours (est.) |
|---|---|---|
| January | 49% | 2.1 |
| February | 65% | 2.8 |
| March | 91% | 3.9 |
| April | 123% | 5.3 |
| May | 137% | 5.9 |
| June | 153% | 6.6 |
| July | 146% | 6.3 |
| August | 135% | 5.8 |
| September | 113% | 4.9 |
| October | 84% | 3.6 |
| November | 60% | 2.6 |
| December | 43% | 1.8 |
Kentucky's curve tops out in June at 153% of the annual average and bottoms in December at 43%, a 3.6-to-one spread with 48% of the year's light landing in four months. In hours: 6.6 a day at the peak, about 1.8 in December.
Half the Kentucky calendar sits above the annual average and half below: April through September are the six months that beat it, carrying 67% of the year's light. April is already worth about 5.3 hours a day, so the productive half of the year starts earlier than most people expect.
Set that against what Kentucky homes actually draw. EIA measured 1,046 kWh a month for the average household here in 2024, 21% above the US figure, which is 26 panels at the annual average sun. Hold the same house to a December and the count goes to 61, 2.3 times higher. Net metering is what makes the first number the one that matters.
Kentucky is small enough, or flat enough, that the sun barely varies across it: the 8 grid cells sampled here span only 4%, west to northeast. The statewide 4.3 figure is a good description of the whole state, which is not something you can say about Texas or Oregon. Shade and roof pitch will move your output far more than address does.
What that sun is worth on a Kentucky bill
| EIA, 2024 residential averages | Kentucky | United States |
|---|---|---|
| Average home's monthly use | 1,046 kWh | 863 kWh |
| Price per kilowatt-hour | 12.79¢ | 16.48¢ |
| Average monthly bill | $133.81 | $142.26 |
| One 400W panel, a year's output | 483 kWh | 506 kWh |
| What that output displaces | $62 | $83 |
Cheap power cuts the other way. Kentucky residential electricity averaged 12.79¢ a kilowatt-hour in 2024, 22% under the national 16.48¢ and 12th cheapest in the country, so the same panel that offsets $83 a year at national rates offsets about $62 here. Nothing is wrong with the sun. There is just less money in each kilowatt-hour it makes.
Here the sun ranking flatters Kentucky. 27th of fifty for sunlight, but only 45th for what a panel earns in a year, a drop of 18 places, and the reason is entirely the price of the electricity being replaced. Maryland gets less sun (4.2 hours to Kentucky's 4.3) and pays 17.86¢ against 12.79¢, so one panel is worth about $23 less a year in Kentucky than in Maryland.
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; 12.79¢ is every Kentucky 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 Kentucky?
About 23 400-watt panels (9.2 kW) for the 900 kWh a month an average US home uses, at Kentucky's 4.3 peak sun hours. For the average Kentucky home specifically, which EIA measured at 1,046 kWh a month in 2024, it is 26. Your own bill is the variable that matters, and the calculator takes any figure.
Is 4.3 peak sun hours good for solar?
It is below the 4.5-hour national average but far from disqualifying. Panel counts run about 5% 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 Kentucky?
About $62. One 400-watt panel at Kentucky's 4.3 peak sun hours makes roughly 483 kWh a year after the 0.77 derate, and Kentucky residential electricity averaged 12.79¢ a kilowatt-hour in 2024 (EIA), which puts Kentucky 45th of the 50 states on this measure against 27th 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 Kentucky?
Yes, by a factor of 3.6 here. NASA's 2001-2020 climatology puts Kentucky's June at 153% of the annual average and December at 43%, so the 4.3-hour figure on this page is the midpoint of a curve running from roughly 6.6 hours a day down to 1.8. Grid-tied homes bank the summer surplus as credit; off-grid designs have to size for the trough, and in Kentucky that means 61 panels for an average local bill instead of 26.