How dot.energy works — and where our numbers come from

The simulation

Rather than apply a flat rule-of-thumb, we run an hour-by-hour simulation of your system across a full year — the same approach professional tools like PVSyst use. We transpose sunlight onto your panels at their tilt and orientation, then subtract real-world losses: angle of incidence, heat, soiling, wiring, inverter conversion, and clipping. The result is a Performance Ratio and an annual energy figure, plus a conservative P90 (a production level you’d beat 9 years in 10) alongside the expected P50.

Weather & sunlight data

Solar resource and temperature come from NASA’s POWER dataset, a satellite-derived record of irradiance and weather. For electricity use, you can rely on a Texas-average profile, your bill, or upload your real Smart Meter Texas 15-minute interval data for the most accurate match — especially with a battery or time-of-use plan.

Your roof

We read your roof from Google’s aerial roof analysis — the tilt and azimuth (facing direction) of each roof plane, its usable area, and how much nearby shade it gets. You can accept those values or adjust them yourself in the system editor.

Electricity rates, bills & fees

For Texas, we model your bill as the utility’s delivery (TDU) charges — drawn from PUCT tariff filings — plus a representative retail-provider (REP) energy rate, with credit for solar you export at that utility’s buyback rate. Permit and interconnection fees come from each city and utility’s published materials.

Be aware: rates, buyback terms, incentives, and fees change with each tariff cycle. We label these as best-effort estimates and link to the official source on each guide so you can confirm the current figure. They’re for orientation, not a binding quote.

Independence

dot.energy is ad-supported, but nobody can pay to change your results. The energy and savings numbers come from the physics and your inputs — not from which manufacturer or installer is advertising. That independence is the whole point.