The federal residential Investment Tax Credit expired December 31, 2025.
This is the most important fact for any Louisville homeowner considering solar in 2026, and it's the one thing most sales pitches still don't tell you. The 30% federal residential solar Investment Tax Credit — Section 25D of the Internal Revenue Code — expired at the end of 2025 under the One Big Beautiful Bill Act signed into law in July 2025.
If a solar salesperson tells you about a "30% federal credit" in 2026, they are either misinformed or hoping you are. Walk away. That number was real through 2025 and is gone.
Kentucky has never had a state solar credit.
Some states offer their own tax incentives that stack on the federal one. Kentucky doesn't and never has. There are no state-level solar tax credits, rebates, or grants for residential installs in 2026. If someone tells you otherwise, ask for the statute number.
LG&E and KU net metering: what you actually get.
Both LG&E and KU offer net metering for residential solar systems up to 45 kW. In 2026 the mechanics work like this: when your panels produce more than you're using, the excess feeds back into the grid and you receive a bill credit at the utility's avoided-cost rate, not at the full retail rate. This is different from the old one-for-one net metering some other states still have.
Practically: solar in Louisville still saves you money, but the math works best when you size the system to your actual consumption rather than oversizing to sell power back. A well-sized system in Louisville today typically has a payback period of 10–14 years, depending on the roof and the household's usage pattern.
TOPCon panels are the current sweet spot.
TOPCon (tunnel oxide passivated contact) monocrystalline panels are the current generation of residential solar. They deliver higher efficiency than the previous PERC panels — typically 21–23% cell efficiency vs. 19–21% — and degrade more slowly over 25 years. In Louisville's mix of hot summers and cloudy winters, that efficiency margin translates to meaningful annual production gains.
Any installer pitching PERC panels in 2026 is selling you last-generation product. Ask specifically what panel model and cell technology they're quoting.
String inverter with per-panel optimizers vs. microinverters.
Two mainstream architectures: a single string inverter with optimizers on each panel, or a microinverter on every panel. Microinverters cost more up front (usually $2,000–$4,000 more on a 7–8 kW system) but simplify shade tolerance and per-panel monitoring. String-plus-optimizer is fine for a roof with clean sun exposure and no shade issues.
For most Louisville houses with clean south-facing roofs, string-plus-optimizer is the right choice. For houses with chimney shading or complex roof lines, microinverters usually pay off.
Roof condition matters as much as the panels.
Solar panels last 25 years. If your roof has 8 years of shingle life left, you're going to be paying to remove and reinstall the array in year 8 — usually a $2,000–$3,500 job depending on system size. If your roof is at end-of-life, replace it before you install solar, not after.
We'll be honest with you about this during the site walk. If the roof needs replacing first, we'll say so before we quote panels.
The realistic Louisville numbers.
A typical 7.6 kW TOPCon system installed on a Louisville single-family home in 2026:
- Install cost: $22,000–$28,000 all-in, no federal credit available
- Annual production: 9,500–10,500 kWh depending on roof orientation
- Annual bill savings at LG&E's 2026 residential rate: $1,400–$1,700
- Simple payback: 13–17 years
- 25-year net savings: $12,000–$20,000 in real terms
Solar in Louisville still works, but the payback math is much longer than it was a year ago. Don't let a salesperson quote you old numbers.