Best caulk for polycarbonate panels?

When I'm done putting my greenhouse together, I was planning to use caulk to seal around the edges of all the panels, both to help keep things fixed in place and also to help prevent cold air from sneaking in. Does it matter what sort of caulk I use, or anything that's OK for outdoor/window/etc should be OK?

When I did mine I was told by the company to just use a silicone caulk. Never really did use much of it though, most edges were enclosed in "joining" strips. I wouldn't want to secure it too tightly, because mine expands and contracts quite a bit, and since it is screwed to a wooden frame, it gets wavy at certain times when it does that. I also have the white color, and would use a more clear product next time, because I feel sometimes my plants get too protected and will burn when I put them out. Legit

use an elastomeric caulk - Poly-Seam-Seal - is one brand name - but you can find others cheaper at lowes or home depot: They will not harden up and will give with the temperature changes: