OwlSolar production estimator
Describe your system from the dropdowns below, add your ZIP code, and this will model an annual production range for a system matching that description in that location. Nothing here needs your paperwork, your login, or an account.
Read this before the number. This is a model, not a measurement of your roof. It says what a system described like yours would be modelled to produce at your ZIP code. It is not a finding about your system, it is not a shortfall, and it cannot tell you whether your system is working properly. That last question is settled by measurement, not by this page.
What this number is, and is not
Now do the part that actually settles it. Open your monitoring app, find your total production over a full calendar year, and compare it to the range above. Only measurement settles it.
Be careful in both directions. The range is wide because panel model, shading and inverter losses all move it, so a system that lands inside this range may still have a dead string or a shaded array, and one that lands below it may be fine for a reason this page cannot see. A single year, compared once, decides nothing on its own.
Every assumption behind it
Each of these moves the number, and this page had to pick a value for all of them.
Model and data
Email yourself a copy
We will send this one report to the address you enter, once, because you asked for it. There is no follow-up sequence.
Why the range is wide
A production model needs about forty inputs to be precise. Six dropdowns give it six. The rest, panel model and its temperature coefficient, string layout, inverter sizing, wiring runs, soiling, snow, and above all shading, have to be assumed, and every assumption widens the band. A narrower number here would be a more confident-looking lie.
The two ends of the range are built from named, checkable things: the dimmest and brightest of five measured years of irradiance at your ZIP code, and a system-loss band from 10% to 22% around the 14% NREL PVWatts default. Shading sits outside both ends, because this page cannot see your trees.
What to do with a number that looks low
Nothing, yet. A single modelled range is a starting question, not an answer. If your actual annual production sits well under the low end, the useful next steps are to check whether any panels or microinverters reported zero for extended periods, whether production dropped after a particular date, and what your contract actually guarantees, which is often written as a percentage of an estimate made by the company that also sold you the system. Our guide to how production guarantees work covers what that promise does and does not cover, and expected versus actual production covers how the comparison is properly made.
Measuring it properly, month after month, against your own contract terms and against measured weather rather than a model of it, is what OwlWatt does. See how it works.