RV Solar Panel Mounting & Sealant Tips

Installing solar panels on an RV can feel intimidating—especially when it comes to getting them sealed right so you don’t end up with leaks later. Over the years at BigBeard Battery, I’ve learned a few tricks that make the job much more foolproof. Below is a step-by-step method I use (and teach to others) that balances reliability, ease, and lasting performance.

1. Start with a Clean, Dry Surface

Nothing beats a good prep step. Before you ever touch tape or sealant:

• Use a gentle cleaner that won’t damage your roof membrane. Denatured alcohol works well. For EPDM, TPO, or PVC roof membranes, a non-chlorinated parts cleaner is safer.

• Avoid leaving any thin film of oil or residue. Even a faint slick can compromise adhesion.

• If you’re out of specialty cleaners, vinegar (diluted) can sometimes work—but rinse afterward and don’t rely on it alone.

A clean substrate ensures your tape or sealant “grabs” onto something solid.

2. Apply Butyl Tape Before Everything Else

This is your first line of defense against moisture infiltration.

• Place butyl or “but” tape between whatever foot you’re laying down (the bracket or base) and the roof surface.

• This tape isn’t your final seal—rather, it helps block water intrusion if your sealant fails or is stressed.

• Once the tape is down, peel off its backing so it’s sticky and ready to bond.

Many professional installs use this two-layer strategy (tape + sealant) to reduce dependence on thick caulk alone.

3. Choose a Sealant That Cures, Not Just Dries

This distinction matters more than most people assume.

• I prefer synthetic or polyurea-type sealants that cure (chemically set) rather than simply drying out.

• Two options I often recommend: Sikaflex 715 or RV Roof Man style products.

• The benefit: a curing sealant better retains flexibility, resists cracking, and stays bonded even under heat, vibration, and movement.

When you run a bead of sealant, aim to get good coverage underneath (between the foot and roof) — don’t just rim it around the edges.

4. Clean the Surrounding Edge, Then Mount Your Feet

Before you commit:

• Use a non-marring pry bar or tool to clean around the edges of the prelaid tape (removing any loose bits).

• Position your mounting feet exactly where they need to go, over the tape and onto the cleaned surface.

• Once set, apply your sealant over the entire base of the foot, sealing the perimeter and screws thoroughly.

One common mistake is letting water “pool” around the feet—try to maintain a slight slope or path so water sheds away rather than gathering.

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5. Seal Behind Hard-to-Reach Spots Using Acrylic Tubing

Here’s a little trick many installers don’t share:

• After your panel is partially mounted, you might not be able to fit your caulk gun behind it.

• By cutting a short section of acrylic (clear plastic) tubing—about ½ inch in diameter—you can feed the sealant through that tube and maneuver it into tight spaces (behind the foot, under edges).

• It gives you just enough reach and control to fill the gaps that are normally unreachable with a gun tip.

This trick helps maintain continuity of seal even in awkward areas.

6. Final Checks: Screws, Seal, and Water Paths

Before wrapping up:

• Use appropriately sized deck screws to secure your feet. Don’t over-torque—just snug tight to compress the sealant without crushing it.

• Make sure all screws are covered in sealant.

• Confirm there’s a clear path for water to shed off—no “valleys” or dips where water can linger.

If all looks good, let your sealant cure fully before driving or exposing it to harsh conditions.

Why This Method Works Better Than Just Caulk

Many DIYers skip tape or rely solely on conventional “caulk” (acrylic, silicone, etc.). The problem: those can dry, shrink, crack, or lose adhesion over time. By combining:

1. A good, clean roof surface

2. A butyl tape “fail-safe”

3. A flexible, curing sealant

4. Careful application and routing

You’re building redundancy into your waterproofing. Even if part of the sealant fails, the tape + sealant combo still gives protection. Experienced RV builders and OEMs often use a similar layered approach for this reason.