Why annual sizing works here
In Georgia, Indiana, Utah and Louisiana, exports earn a small fraction of retail, so a system matched to annual consumption still gives away much of its midday output. The design has to chase daytime load instead.
Under Kentucky Utilities full retail net metering that problem does not arise. Timing does not change the value of a kilowatt hour, so annual totals are a valid basis for sizing.
Senate Bill 100 raised the eligible system size from 30 kW to 45 kW, so the programme limit is far above anything a residential design would reach. Your consumption is the practical constraint rather than the cap.
That makes the conversation straightforward: what did you use over the last twelve months, and what percentage of that does the proposed system cover.
Simpler does not mean unlimited
Retail credit makes exports as valuable as consumption; it does not make surplus valuable beyond your annual usage. A system generating more across a year than your household uses is producing electricity you cannot offset against anything.
Ask what happens to credit that exceeds your annual consumption under your specific tariff, and whether there is any point at which it is reconciled, forfeited or paid out. That answer belongs in the design conversation.
Ask what percentage of your annual usage the proposed system covers. A design meaningfully above 100 percent should have a specific reason behind it.
The good reason is a concrete planned increase in load, such as an electric vehicle or a heat pump. A general expectation of using more electricity later is not.
Confirm the arrangement in writing
Kentucky compensation terms are set per utility, and one large Kentucky utility has already moved away from retail credit to an avoided cost rate. That makes it worth confirming your own position rather than assuming.
Ask your installer to state in writing which net metering arrangement your account would be on, and ask Kentucky Utilities directly to confirm it.
Ask also what would happen if the arrangement changed after you install, and whether existing customers would be grandfathered. The utility that moved to avoided cost grandfathered systems in service by December 31, 2024 for 25 years, which is the pattern to ask about.
That is not a reason to hesitate. It is a reason to have the answer documented before you commit to a twenty-five year asset.
Rebuilding the arithmetic on Kentucky terms
The 30 percent federal Residential Clean Energy Credit under Section 25D expired for property placed in service after December 31, 2025, so a cash or loan purchase in Lexington receives no federal tax credit, and Kentucky has no state solar tax credit.
Section 48E survives at 30 percent for third-party owners under leases and power purchase agreements, so ask what a provider claims and what reaches you in the rate.
What exists is full retail net metering under the Kentucky Utilities arrangement, an eligible system size up to 45 kW, and the electricity you stop buying at around 15 cents per kWh.
Ask for the design built from twelve months of your own bills, the percentage of annual usage stated, and the net metering arrangement confirmed in writing by the utility.