Solar panel stopped working

Tirril

Just had a PV Solar 120 watt roof mounted solar panel fitted which has worked fine for a week charging up to 20 volts. Suddenly not charging at all. Have checked the fuse by the battery which is ok. Then disconnected the wires from the panel from the charge
controller but found no power coming from the panel. The only possible other fuse could be hidden in a junction box mounted on the roof near the panel. I could understand if the charge unit had failed but puzzled as it seems the panel itself is too blame.
Any suggestions before I have to trail the caravan back to the dealer which is some distance away.