Can solar panels cause roof leaks?

How can a solar installation cause a roof leak?

On a sloped roof the racking usually rests on brackets screwed through the shingles and into the rafters. Each bracket is a hole in the waterproof layer that has to be sealed again. A leak starts if the bolt misses the framing, the sealant is missing or has aged, the flashing is the wrong type for the roofing material, or a shingle is cracked during the work.

The leak may not show up for months. Water may follow a rafter or the underlayment before it appears as a stain, so a problem in the first winter may be traced to work done the previous summer. Snow and ice make things worse: meltwater can back up under shingles around the fixing, which is why a careful job matters more in Canada than in a dry climate. The snow removal guide shows how snow behaves on an array.

What is flashing and why does it matter?

Flashing is a shaped piece of metal or other waterproof material that sits under the roofing and over the bracket, directing water over the penetration instead of into it. For solar, installers commonly use a flashed mount that slides under the course of shingles above and is sealed to the surface below. Metal, tile and membrane roofs each need their own detail, and a product made for asphalt shingles is not suitable for a tile roof.

Ask your installer which flashing product and method will be used on your roof, and whether it fits the roofing manufacturer's rules. Mounting systems that clamp onto the seams of a standing-seam metal roof avoid holes altogether, and flat roofs may use ballast, a heavy weight in place of fixings, if the structure can carry it. The roof requirements checklist describes how roof type affects the choice.

What are the signs of a leak after installation?

Look inside as well as out. Common signs are a brown or yellow stain on the ceiling below the array, a damp patch on the attic sheathing, wet insulation, a musty smell and bubbling paint. In the attic, check around the bolts that come through the roof on a cold, wet day for drips or frost. Water that shows after rain or during a thaw points to an exterior source.

• Take dated photos of the roof and attic before the work starts, as a baseline.
• Check the attic after the first heavy rain and the first thaw.
• Keep the contract, the invoice and any roofing details together in one file.

What should you do if the roof leaks?

Contain the water and limit the damage first, with a bucket and, if safe, a tarp over the ceiling area. Then contact the installer in writing with photos. A reputable company inspects, finds the source and repairs it under its workmanship warranty. If the problem looks like old roofing rather than the panels, a roofing contractor can tell you.

Do not allow anyone to patch the area with household caulk before the cause is found. Notify your home insurer if there is water damage, and see insurance after a solar install for what to ask. The solar panel warranty guide explains how product, performance and workmanship cover differ.

How can you prevent roof leaks before installation?

Start with the roof itself. A worn roof should be repaired or replaced before the array goes on, which the roof requirements guide explains. Choose an installer with a track record on your roof type and ask for references. Our solar installer checklist lists what to request, and the installation process guide shows where inspections fit.

Get the roof penetration warranty in writing, with its length and what it covers. Ask whether the roofing manufacturer's warranty stays valid with panels attached, and keep any approval letters.

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