How to Use the Solar Panel Row Spacing Calculator
When installing solar panels in multiple rows, a front row that casts a shadow on the row behind it can significantly cut that row's energy output. Enter your panel's vertical projected height and the sun's elevation angle, and this calculator instantly returns the minimum row spacing needed to avoid shading.
The math is simple trigonometry: if h is the vertical height a tilted panel projects and θ is the sun's elevation angle, the shadow length equals h divided by the tangent of θ. A lower elevation angle (the sun sitting lower in the sky) casts a longer shadow, so you need more spacing between rows.
For the most conservative design, use the solar noon elevation angle on the winter solstice (around December 21), the day the sun sits lowest in the sky all year. Designing for zero shading at that point naturally leaves extra margin for the rest of the year. Sites at higher latitudes have a lower solstice angle, so the same panel height will need noticeably more spacing there.
Frequently Asked Questions
The most conservative approach is to use the solar noon elevation angle on the winter solstice (around December 21). Higher latitudes have a lower solstice angle, which requires more spacing.
The rear row will be shaded by the front row for longer periods, which can significantly reduce winter energy production.