Solar panels on or around a dormer

Anyone saying 'solar panels and dormer' usually means one of two things. Either: can panels go on the dormer's own flat roof? Or: how do I lay panels on the main roof with a dormer in it? They are different questions with different answers, so we treat them separately.

What both share: it comes down to a tailored layout. A dormer does not make a roof unsuitable, it makes it a puzzle.

The flat top of a dormer is often usable, with two caveats from our installation practice. The first is the structure: a dormer is usually built light, with a wooden frame not designed for much extra weight. Ballasted frames, as on a normal flat roof, are therefore often unwise there; sometimes we choose an anchored mounting or conclude the small roof cannot take it. We judge that during the survey, not from a photo.

The second is size. A dormer roof usually fits two to four panels, and the placement rules take a bite out of that: on a flat roof a panel must stay at least as far from the roof edge as the panel is high. On a small roof surface that margin weighs heavily. Smaller panel formats or a landscape layout often work better here; the available sizes are covered in solar panel dimensions.

A dormer breaks up the roof surface and casts shade on the panels beside and above it during parts of the day. We account for that in the layout in two ways. We place panels where the shade falls least, sometimes landscape instead of portrait, so a full row still fits around the dormer.

And where structural shade is unavoidable, we work with per-panel electronics: optimizers or micro-inverters make sure a shaded panel does not drag the rest down. That way the dormer only costs the output of the panels it actually hits.

Solar panels on a roof are permit-free in principle in the Netherlands, including on and around a dormer, as long as you meet the conditions. On a pitched roof: within the roof surface, directly on it and at the same pitch. On a flat roof, which includes the dormer top: the distance to the roof edge must be at least equal to the panel's height. This is set out by the Informatiepunt Leefomgeving (Dutch).

Exceptions exist for listed buildings and protected town- or villagescapes; a permit may still be required there. If in doubt, run the permit check at the Omgevingsloket or ask your municipality. We flag it in the quote if your situation calls for it.

Be honest with the numbers: a dormer usually costs a few panels of layout space compared with a bare roof surface, and the panels on the dormer top lie flat, which yields slightly less per panel than the ideal pitch. In return, every panel that does fit simply contributes. Whether the total covers your consumption is checked via how many solar panels do I need.

If you also have an extension or garage with a flat roof next to the pitched roof, we include it in the same layout; how that works is covered in solar panels on a flat roof.

During the survey we assess the dormer's structure, measure the roof surface and draw the layout with and without panels on the dormer. That way you see up front what each variant yields and costs, instead of a standard row of panels that fits on paper but disappoints on the roof.

Put your dormer situation to us or start on the solar panels page.