The Density-Shading Tradeoff
Solar array design is fundamentally a tradeoff between density and shading. Packing modules closer together increases the total nameplate capacity on a given roof area, but the front rows cast shadows on the rows behind them, especially during winter when the sun sits low on the horizon. Finding the sweet spot — maximum energy per square meter of available space — requires balancing tilt angle, row spacing, and local latitude.
Row Spacing Geometry
The minimum row spacing to avoid shading at a given sun elevation angle follows simple trigonometry. The shadow cast by a tilted panel extends a distance equal to its height divided by the tangent of the sun angle. For a 30° tilt panel that is 1.7 meters tall, the projected height is about 0.85 m. At the winter solstice at 40°N latitude, where the noon sun angle is only 26.5°, the shadow extends 1.7 meters — demanding at least that much gap between rows.
Azimuth and Seasonal Effects
While due south is optimal for annual energy in the Northern Hemisphere, slight azimuth rotations have surprisingly small penalties. A 15° rotation from south costs less than 2% annual energy. Some designers deliberately orient panels southwest to capture more afternoon sun, which often coincides with peak electricity prices. East-west layouts on flat roofs sacrifice per-panel output for higher ground coverage ratios.
Interactive Array Designer
This simulation renders a top-down and cross-section view of your array layout. Adjust row count, tilt angle, spacing, and azimuth to visualize shadows at different times of year. The energy density readout shows annual kWh per square meter of roof, accounting for shading losses. Watch how tightening the spacing initially increases energy density but eventually loses energy to shadows.