Methodology
How SolarAlign Calculates Solar Production
Every SolarAlign calculator runs on the same transparent engine. Here is exactly how it works, what we assume, and where it has limits.
Solar Geometry
We compute the sun's position using standard solar position equations, the same family of algorithms used by NOAA and industry tools. Given latitude, longitude, date, and time, we derive the sun's elevation and azimuth above the horizon.
The engine is implemented in the site's solar library and powers the tilt, azimuth, production, and location calculators.
Latitude & Longitude
Your coordinates determine everything else. Tilt and azimuth recommendations are computed from your latitude; peak sun hour estimates also account for your hemisphere and region.
You can enter coordinates directly, allow geolocation, or pick from our city database.
Tilt & Azimuth
Year-round tilt uses a latitude-based optimum; seasonal and monthly values follow the sun's declination over the year. Azimuth targets true south (northern hemisphere) or true north (southern hemisphere). We report magnetic vs true north guidance where relevant.
Seasonal adjustment captures most of the benefit of monthly adjustment with far less effort — we say so explicitly in the calculators.
Irradiance & Peak Sun Hours
Production estimates start from "peak sun hours" (PSH) — the equivalent number of hours per day of full 1000 W/m² sunlight for your latitude. PSH is derived from published solar resource averages.
PSH is a monthly/seasonal average; actual weather, clouds, and local terrain will make real output vary from the estimate.
System Losses
Production is reduced by a configurable system-loss factor covering soiling, wiring, inverter conversion, and other real-world losses. The production calculator defaults to a reasonable combined loss and lets you adjust it.
Temperature Effects
Hot panels produce less than rated. In warm and tropical climates, high operating temperatures reduce output beyond rated conditions. Our estimates account for a typical temperature penalty.
Panel Efficiency & Degradation
ROI and payback calculations apply a standard annual degradation rate (default 0.5%/year) so 25-year savings reflect panels that produce a little less every year, not a flat lifetime output.
Battery Assumptions
Where battery backup is discussed, we use round-trip efficiency and depth-of-discharge assumptions typical of lithium battery systems. Battery economics depend heavily on local pricing, so we treat them as estimates, not quotes.
Data Sources & References
Where possible we cite public references for typical values. Primary sources include NOAA solar position algorithms and published solar resource datasets.