How much adhesive do I need for a solar panel bracket?

If you're using adhesive you want as much surface area connection between the bracket and the roof. A couple inches of bracket may not be enough. Using adhesive under Unistrut that matches the full length of the solar panels is much better. But I'm a lot more comfortable with actual fasteners.

Can you use adhesive on solar panels?

I strongly urge you to avoid using any adhesive for solar panels. Keep in mind that flexible solar panels don't last long. You will probably need to replace them every couple of years. That will be a challenge with them glued in place. For rigid panels, the best adhesive would be M6 bolts.

How do you secure a bracket to a roof?

Butyl tape between the bracket and the mounting surface and then Dicor Self Leveling Lap Sealant around the edge of bracket and on top of the fastener is the way to ensure there is no water intrusion. How long are your brackets? If you're using adhesive you want as much surface area connection between the bracket and the roof.

What is the best adhesive for rigid panels?

For rigid panels, the best adhesive would be M6 bolts. These are rigid panels being mounted on aluminium brackets. I'll actually be replacing one of the factory panels and notice they only use adhesive. M6 bolts make sense for strength, my concern is they introduce an entry point for moisture.

Can I use eternabond under a bracket?

Though using double sided Eternabond under the bracket would work as both adhesive and butyl tape (along with a fastener). No adhesive would be necessary in that case. Waterproofing.