About OwlWatt
OwlWatt is an independent measurement service for residential solar systems. We read the same production data your installer reads, run the same physics-based models the National Renewable Energy Laboratory publishes, and tell you what your panels should have produced — so you can compare that against what they actually did.
We don't sell panels. We don't take commissions from installers. We're not a marketplace. We measure.
Why this exists
I bought solar in 2024. The first month's production looked off. When I asked my installer about it, they said it was within the expected range. When I asked what range that was, they said it varied. When I asked for the model they used to set expectations, they said they didn't have one I could see.
I'm a network engineer. I've spent fifteen years measuring things — packet flows, error rates, latency budgets. The idea that a $30,000 piece of equipment on my roof was producing what it was supposed to, and the only way to know was to take the installer's word for it, sat badly with me.
So I pulled my own data — Enphase's API exposes per-microinverter, per-5-minute production records — and built the model myself. The 2024 data showed about an 11% shortfall against PVWatts modeling for my latitude, tilt, and panel specifications. I drafted a letter to my installer citing the model, the data, and the contract clause that promised the production guarantee. They acknowledged the shortfall and scheduled a panel-by-panel inspection within two weeks.
Then I realized every solar homeowner has the same problem. Production guarantees exist on paper in most installer contracts. Almost nobody enforces them, because almost nobody has the tools or the time to document the shortfall the way a warranty claim requires.
OwlWatt is the tool that documents it.
What we measure
- Production: 5-minute resolution from your inverter (Enphase microinverters or SolarEdge string inverters), with per-panel granularity where available.
- Expected production: pvlib-PVWatts model parameterized with your specific system — DC nameplate capacity, tilt, azimuth, install date for degradation, your local clear-sky irradiance. Same library NREL publishes, same model PVWatts.gov uses.
- Shortfall: measured minus expected, integrated over any window — today, this month, year-to-date, since install. Stored as kWh and translated to dollars at your local tariff rate.
- Documentation: when a shortfall persists, we produce a warranty claim letter citing the specific contract clauses, the model parameters, the data window, and the cumulative dollar value of the shortfall. The letter is yours to send.
For the full technical methodology, see /methodology.
Who we are
Olivier Beauchemin · Founder
What we don't do
- We don't recommend installers. The whole point of being independent is that we're not financially aligned with anyone selling you a panel. We never have been; we never will be.
- We don't take installer commissions. No referral fees, no co-marketing, no white-label deals.
- We don't sell your data. Your production data is yours. We use it to produce your reports and nothing else. See our privacy policy for the binding version.
- We don't claim to be lawyers. A warranty claim is a legal action. We produce the technical documentation; if your installer disputes the claim, you'll want a licensed attorney in your state. We're happy to share our methodology with one.
Get in touch
If you're already an OwlWatt customer and need help with your dashboard, /help is the fastest path. If you have a question about how the methodology works, or you're a journalist or researcher, email [email protected].