About the Shadow & Row Spacing
Inter-row (shadow) spacing is the minimum gap between tilted rows of solar panels so that one row does not shade the row behind it during useful sun hours — typically evaluated at the winter solstice between 9 am and 3 pm.
Formula
Row spacing ≈ Panel height × ( cos(azimuth factor) ÷ tan(sun elevation) )
- Panel height
- Vertical height of the tilted module row (m)
- sun elevation
- Solar elevation angle at the design time (winter 9am–3pm)
How to calculate it
- 1Compute the tilted row's vertical height from module length and tilt angle.
- 2Find the minimum solar elevation angle for your latitude at the design time (winter solstice, ~9 am).
- 3Use the shadow-length relationship to get the minimum spacing that keeps the next row unshaded.
- 4Balance spacing against land/roof area — tighter spacing raises density but increases shading losses.
Worked example
A 1 m tall tilted row at a site where the winter 9 am sun elevation is ~23° needs roughly 1 ÷ tan(23°) ≈ 2.4 m of horizontal spacing to stay shadow-free during the critical window.
What you can calculate
- Winter solstice model
- City quick-picks
- Row pitch & GCR
- Area per MW
Standards & references
Key definitions
Definitions from the SolarPedia glossary
Frequently asked questions
Why is inter-row spacing evaluated in winter?
The sun is lowest in the sky around the winter solstice, casting the longest shadows. Spacing that keeps rows unshaded in winter will be shadow-free the rest of the year, so winter is the worst-case design condition.
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