Only use a “100% silicone” sealant on polycarbonate sheets. Silicone sealants do not degrade in sunlight. They resist mold and mildew and remain flexible, allowing for building movement.
Do not use roofing caulk. Consequences of using an incompatible sealant are inadequate adhesion, too rigid of a bond, and/or the product contains chemicals that may discolor or damage the polycarbonate sheet.
Check the product information on the sealant label BEFORE using to ensure compatibility.