How much does shading affect solar panels?

Even partial shading can significantly reduce output. A single shaded panel in a string can reduce the entire string's output by 30-50% with conventional string inverters. Using microinverters or power optimisers limits the impact to just the shaded panel(s).

How far should panels be from obstructions?

The minimum clear distance depends on the obstruction height and UK latitude. At 52°N (Midlands), an obstruction 4m above the panel height needs at least 6m clearance to avoid shading at the winter solstice. The rule of thumb is 2-3 times the height difference.

Do deciduous trees cause less shading?

Yes, deciduous trees lose their leaves in autumn/winter so they cause less shading in winter months when the sun is lowest. However, bare branches still block 20-40% of light. The main shading impact is actually in summer when trees are in full leaf but the sun is higher.

What is the sun angle in the UK?

The sun's altitude at solar noon varies from about 15° in December to 62° in June at 52°N latitude (central England). At 56°N (central Scotland), it ranges from 11° to 58°. The low winter sun angle means shadows are longest in December.

Can MCS accept a shaded installation?

MCS requires a shading assessment as part of the design. Systems with significant shading (>20% annual loss) may not qualify for MCS certification, which is required for SEG payments and BUS grants. Power optimisers or microinverters can mitigate shading and may help achieve certification.

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Solar Shading Calculator

Assess the impact of nearby obstructions on solar panel performance. Calculate shadow lengths, annual yield loss and financial impact for UK latitudes.

Obstruction Type

Obstruction Height

Height above ground

Panel Height

Height of panel centre

Distance to Obstruction

Horizontal distance

Array Size

For yield loss calculation

Assessment Month

December is worst case

How We Calculate This

This calculator assesses solar shading based on obstruction geometry and UK sun angles.

The formula

Shadow length = Height difference ÷ tan(sun altitude angle)

Sun angle = 90 - latitude + solar declination
December declination: -23.5°
June declination: +23.5°
Panels shaded if shadow length > distance to obstruction

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.