Frequently asked questions
Why is south (or north) usually the best direction?
Solar panels capture the most energy when they face the sun's daily arc. From the Northern Hemisphere the sun's arc is in the southern sky, so panels face south; from the Southern Hemisphere it is the opposite. Local climate — like morning fog or afternoon clouds — can shift the true optimum a few degrees, which is why we compute it from real irradiation data instead of assuming.
What does the tilt angle change?
Tilt controls how squarely your panels face the sun's average height in the sky. Too flat wastes winter sun; too steep wastes summer sun. The recommended tilt maximizes total energy across the whole year for your latitude and climate.
Is this true north or compass north?
All directions here are relative to true (geographic) north. A magnetic compass points to magnetic north, which differs by the local magnetic declination — shown with your result so you can convert.
How accurate is the estimate?
Solar geometry is accurate to a fraction of a degree, and irradiation data comes from decades of satellite measurements (PVGIS / NASA POWER). What we cannot see is your local shading — trees, chimneys, nearby buildings — which can matter a lot. Treat the result as the correct starting point, and have an installer verify shading on site.
My roof doesn't face the optimal direction. Is solar still worth it?
Usually yes. Deviating 30–45° from the optimum typically costs only 5–15% of annual yield. Use the “Compare your roof” tool to see the exact number for your orientation.
Do you store my location?
No. Coordinates are used to compute your result and are never stored with any identity. The app works without an account, and your language preference stays on your device.