Solar Shading Loss Calculator

Solar Shading Loss Calculator

Partial shading can cost a solar system more output than you'd expect - this calculator quantifies the real impact on annual energy production.

Actual Output = Unshaded Output x (1 - Shading Loss %)

Example

An unshaded system rated for 9,000 kWh/year, 15% shading loss:

Actual Output = 9,000 x (1 - 15%) = ~7,650 kWh (1,350 kWh lost)

Why Even Small Shading Causes Disproportionate Loss

Partial shading on even a small portion of a solar array can disproportionately reduce total output beyond that shaded area's share alone - traditional string inverters drop the output of an entire series-connected string down to match its most-shaded panel, meaning one shaded panel can drag down many unshaded ones with it.

Microinverters and Power Optimizers Can Reduce This Loss

This is a key reason microinverters or panel-level power optimizers are recommended for partially shaded roofs - both allow each panel to operate independently at its own maximum output rather than being limited by the weakest panel in a shared series string.