It's upgraded from regular rigid folding solar panel,different from other folding solar kits,it use ETFE surface,higher weather resistance.more durable,longer life span and better performance of waterproof.Fabric is light than glass or aluminium as well.Back contact cells makes our folding solar kits smaller size,higher cell efficiency,less power loss under crack,better performance under weak sunshine.The panel max voltage are around 20v,it's designed for lithium battery along or in portable power stations,can charge all kinds of solar batteries,portable power generators.