What is a normal amount of solar production per kW?

Annual production per installed kW (specific yield) varies by location: roughly 1,100–1,250 kWh/kW in the Northeast and Pacific Northwest, around 1,300–1,450 in the Midwest and Southeast, and 1,600–1,800+ in the Southwest. These are statewide averages from NREL's PVWatts model; your own roof's tilt, azimuth, and shading shift the real number.

Is this estimator accurate enough for a warranty claim?

No. This is a rough screen using statewide averages and ignores your roof's orientation, shading, and the actual weather. A production-guarantee or warranty claim needs a weather-adjusted, methodology-backed comparison against your contract's specific guarantee number — that is what OwlWatt produces.

Is my solar underproducing?

Q: How do I know if my solar panels are underproducing?

Compare your system's actual annual production to what a correctly working system of your size, in your location, would typically produce. As a rough screen, take your system's DC size in kilowatts and multiply by your region's typical specific yield (annual kWh per installed kW). If your actual output is well below that — under about 80% — something beyond normal derating may be wrong. A precise answer requires weather-adjusting the comparison to your roof's orientation and the actual sunlight during the period, which is what OwlWatt does.

A free, instant rough estimate. By Olivier Beauchemin · Updated June 2026

Enter four numbers and this tool compares your system's actual output to the state-average output for a system your size and age in your state. It's a quick screen to tell you whether a closer look is worth it, not a precise or contract-grade figure (more on that below).

System size (kW DC)

State

Install year

Your actual production (kWh / year)

How the estimate works

expected ≈ size(kW) × your state's NREL average yield (kWh/kW/yr) × (1 − 0.5%/yr × system age)
ratio = your actual ÷ expected

What this can and can't tell you. This uses statewide-average sunlight (from NREL's PVWatts model) and a standard degradation rate. It does not account for your roof's tilt, the direction it faces, shading from trees or chimneys, or the actual weather during your period, all of which move the real number. So treat the result as a yellow/green/red flag, not a verdict. A defensible figure (measured against your contract's specific guarantee and weather-adjusted to your roof) is what OwlWatt produces.

Got a red or yellow flag?

This estimator screens with averages. OwlWatt documents your exact shortfall against your contract's production guarantee (weather-adjusted, using NREL's PVWatts model) in a report you can take to your installer. Card-free to start.

Start free, check my system

What counts as "underproducing"?

No solar system hits its nameplate rating, temperature, inverter clipping, wiring losses, and a little dust all shave output, and panels degrade slowly (about 0.5% a year). A healthy system still lands within roughly 90–100% of a properly modeled expectation over a year. The screen above flags three bands:

≥ 90%, in the normal range for a rough, averages-based check.
80–90%, a bit low; worth a closer, weather-adjusted look.
under 80%, materially below the state average; a real fault, shading change, or a broken guarantee is worth investigating.

Because this ignores your roof's specifics, a low result isn't proof of a problem, but it's a strong reason to get a precise comparison. See expected vs. actual production explained for why panels never hit their rating, and how to escalate a documented shortfall if your installer won't honor a guarantee.

Common questions

How do I know if my solar panels are underproducing?

Compare your actual annual output to your system size × your region's typical yield (kWh per kW per year). Well below that (under about 80%) suggests more than normal derating. A precise answer weather-adjusts the comparison to your roof, which is what OwlWatt does.

What's normal production per kW?

Roughly 1,100–1,250 kWh/kW/yr in the Northeast and Pacific Northwest, ~1,300–1,450 in the Midwest and Southeast, and 1,600–1,800+ in the Southwest, statewide averages from NREL PVWatts. Your roof's tilt, direction, and shading shift it.

Is this estimate good enough for a warranty or guarantee claim?

No, it's a rough screen on averages. A claim needs a weather-adjusted figure measured against your contract's specific guarantee number. OwlWatt produces exactly that.