# The Science of Solar Tilt
The difference between a zero-euro electricity bill and an underperforming investment lies, literally, in the angles. Solar radiation is not uniform — it is a dynamic flow that changes with the hour, the day, and the season. Understanding celestial geometry is the first step to turning your roof into a high-performance power plant. Lat × 0.87 General Formula
Lat × 0.76 + 3.1 Latitudes 25°–50°
± 15° Seasonal Adjustment
The Perpendicularity Principle
A solar panel works like a net catching photons. It is most effective when facing the flow directly, at 90° to the solar rays. Any deviation reduces the effective capture area.
- Maximises the effective capture surface
- The basis of all tilt calculations
Why Latitude Matters
Your location on the globe dictates the maximum height of the sun. The further from the equator, the lower the sun travels and the more vertical the panel needs to be to intercept it.
- Higher latitude means greater tilt needed
- Near the equator, panels are nearly flat
# Seasonal Strategies
Summer: The sun reaches its zenith. Panels should be nearly flat — subtract ~15° from your latitude. Take advantage of long days and intense direct radiation. Winter: The sun travels low near the horizon. Tilt panels steeper by adding ~15° to your latitude. A steeper angle also helps snow slide off without blocking the cells.Fixed Installation or Seasonal Adjustment?
Fixed (standard): Set to the optimal annual angle. Less maintenance and better wind resistance, with only a 5-10% loss compared to solar tracking. Seasonal adjustment (pro): Change the angle 2-4 times a year to gain up to +15% performance during winter months.
Keys to an Efficient Installation
The optimal annual angle is your main reference for fixed installations.
Losses from deviations of ±5° are less than 3% of annual production.
Prioritise avoiding partial shade over finding the exact angle.
In the Northern Hemisphere, always orient panels to face South.
Seasonal adjustment 2-4 times a year can improve winter performance by up to +15%.