How do solar panels mount on a metal roof?
Short answer. On a standing seam roof, solar racking usually attaches with clamps that grip the raised seams, so no holes go through the roof. On exposed-fastener metal, mounts fasten through the high ribs of the panels into the structure below with sealed brackets made for that panel profile.
Standing seam
- Seam clamps tighten onto the vertical seams with set screws, and the rails or panels attach to the clamps.
- No penetrations means no new leak points, which is why standing seam and solar are a popular pairing.
- The clamp must match the seam profile, and the roof's own clips have to carry the added wind load; on larger arrays that is a question for the panel maker or an engineer.
Exposed-fastener panels
- Brackets mount on top of the ribs, the high points of the panel, with sealing gaskets, fastened into the deck or purlins.
- Mounting in the flat part of the panel, where water runs, invites leaks.
- Screws on an older roof may already be due for replacement; do that before the array covers them.
Things to settle first
- Remaining life. Metal often outlives the panels, which is an advantage, but an exposed-fastener roof near the end of its coating life should be addressed before installation.
- Warranties. Ask whether the metal roof maker's or installer's warranty is affected by the mounting method.
- Grounding. Racking must be bonded and grounded per the electrical code; the solar installer handles this.
- Hail. Panels and metal both take hail. Know how your policy treats each, including any cosmetic damage exclusion on the metal.
Related reading: metal roofing in Georgia and replace your roof before solar.