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.