Solar Panel Calculator for Louisville, KY
Estimate the cost, savings and payback of solar panels in Louisville, KY, using local NREL sunshine data, Kentucky prices and electricity rates.
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Louisville gets about 4.74 peak sun hours a day on a south-facing roof, so each kW of panels makes about 1,328 kWh a year. That ranks #72 of the 111 cities on this site. Output peaks in Jun and is lowest in Dec.
Sunshine in Louisville by month
What an 8 kW system makes in Louisville
| Month | Sun hours a day | Output | Bill savings |
|---|---|---|---|
| Jan | 3.02 | 624 kWh | $89 |
| Feb | 3.59 | 664 kWh | $94 |
| Mar | 4.14 | 824 kWh | $117 |
| Apr | 5.55 | 1,040 kWh | $148 |
| May | 5.73 | 1,072 kWh | $152 |
| Jun | 6.44 | 1,136 kWh | $161 |
| Jul | 6.16 | 1,104 kWh | $157 |
| Aug | 6.06 | 1,088 kWh | $154 |
| Sep | 5.60 | 1,000 kWh | $142 |
| Oct | 4.27 | 808 kWh | $115 |
| Nov | 3.43 | 672 kWh | $95 |
| Dec | 2.83 | 592 kWh | $84 |
| Year | 4.74 | 10,624 kWh | $1,509 |
Savings at 14.20¢ per kWh (Kentucky average), with every kWh credited at that price.
Cost and payback by system size
At $2.48 per watt, the Kentucky average, before incentives.
| System | Cost | Year 1 savings | Payback | 25-yr gain |
|---|---|---|---|---|
| 4 kW | $9,920 | $754 | 13.6 yrs | $7,848 |
| 6 kW | $14,880 | $1,131 | 13.6 yrs | $11,773 |
| 8 kW | $19,840 | $1,509 | 13.6 yrs | $15,697 |
| 10 kW | $24,800 | $1,886 | 13.6 yrs | $19,621 |
| 12 kW | $29,760 | $2,263 | 13.6 yrs | $23,545 |
How many panels you need in Louisville
| Monthly use | System | 400 W panels |
|---|---|---|
| 500 kWh | 4.52 kW | 12 |
| 750 kWh | 6.78 kW | 17 |
| 1,000 kWh | 9.04 kW | 23 |
| 1,500 kWh | 13.55 kW | 34 |
| 2,000 kWh | 18.07 kW | 46 |
Covering 100% of a year's use at 1,328 kWh per kW.
Common questions
Is solar worth it in Louisville?
At local averages an 8 kW system costs about $19,840 before incentives, saves about $1,509 in its first year and pays back in about 13.6 years.
How many peak sun hours does Louisville get?
About 4.74 a day over the year on a south-facing roof at 20°, from 2.8 in Dec to 6.4 in Jun, according to NREL's PVWatts model.
How much does a 1 kW solar system produce in Louisville?
About 1,328 kWh a year, or 111 kWh a month on average.
Is there a federal solar tax credit?
Not for homeowners who buy their system. The 30% Residential Clean Energy Credit ended for systems installed after December 31, 2025.
Sources
- NREL PVWatts V8 API (south-facing, 20° tilt, 14% losses, typical-year weather): https://developer.nlr.gov/docs/solar/pvwatts/v8/
- EnergySage, Solar panel cost by state (updated November 6, 2026): https://www.energysage.com/local-data/solar-panel-cost/
- U.S. EIA, Electric Power Monthly, Table 5.6.B (residential price, Jan–Aug 2026): https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_b