solar panel question

Has anyone used this panel for their charging needs?I have no idea how any of these work.How long would it take to charge a battery that was say 3/4 discharged?Can they be placed outside the camper when being used and brought in or do they have to be permanently mounted.I know there have been questions asked on the ad for the panel,but I prefer to ask people that have actually used them.And are they actually worth buying and depending on?Thanks for any and all advice.
http://www.campingworld.com/shopping/it ... 6006#qanda
http://www.campingworld.com/shopping/it ... 6006#qanda