Solar on slate, tile and cedar shake roofs in Illinois

Usually, with the right installer. EnergySage notes that tile installs often mean removing tiles and swapping them for mounting feet and flashing because the tiles are brittle, which raises labor costs, and it advises confirming your installer has tile experience. It also cautions that most installers aren't comfortable working on wood shake roofs, and that slate and wood installs cost more.

• Tile hooks: the installer lifts or cuts a tile, bolts a hook to the rafter with flashing on the roof deck, and the hook passes between tiles to hold the rail. IronRidge and QuickBOLT both make tile hooks with deck flashing.
• Tile replacement flashing: a metal piece shaped like the tile replaces it at each mount, so no tile is cut. IronRidge and QuickBOLT sell these for common tile profiles.
• Comp-out: tiles under the array are removed and replaced with composition shingles, the array is mounted like a shingle roof, and tiles go back around the edges. Keep the removed tiles as spares for future repairs.

Ask which method the installer will use and who replaces any tiles that break. Matching old clay tile or slate can be hard, so spares matter.

Slate sits flat and tight, with little room for a hook to slide underneath, and installers who specialize in it say it should never be drilled. It's also heavy: Winnetka's residential solar application lists slate as a heavyweight roof and requires a review of the roof's structural details. A slate roof can also outlast several solar systems, so a careless install can do more damage than the panels are worth.

If your slate is in good shape, ask for installers who have done slate before and for photos of their work. If not, look at another spot for the panels.

It's the hardest of the three. Many installers won't take it on, and cedar shake usually wears out well before slate or tile, so you may want to replace the roof first. In Lake Forest, homeowners asking the Historic Preservation Commission in 2024 to replace cedar with synthetic slate cited hail damage and insurance costs. If you're replacing a worn shake roof anyway, put the solar on the new roof. See should you replace your roof before solar?

Premium roofs are common on older homes, and older homes are often in historic districts. Oak Park's solar guidelines ask for panels where they aren't readily visible from the street, such as rear roof slopes, behind dormers or on garages behind the house, installed so they can be removed without damaging the historic structure. Panels on a street-facing slope need a certificate of appropriateness. Ask your village before you sign. See solar permits in Illinois, town by town.

• A detached garage or outbuilding with a simpler roof. See solar on a detached garage or barn.
• A ground mount in the yard, if you have the space. See ground mount vs. roof mount.
• A rear roof slope that faces east, west or south, out of view from the street. See east- and west-facing roofs.

Many homes with premium roofs also have large bills and older trees, so ask the installer to compare all three before deciding.

1. 1

   How many roofs like mine have you done?

   Ask for addresses or photos of slate, tile or shake jobs.

2. 2

   Which mounting method will you use?

   Tile hooks, replacement flashings or a comp-out, and why.

3. 3

   Who covers broken tiles or slates?

   Get it in writing, including after-install service visits.

4. 4

   Does my roof need an engineer's review?

   Heavy roofs like slate may need a structural check for permits.

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