I bought a 70watt flexible panel from a south wales manufacturer
it started to be temperamental in that it would always work first thing in the morning but by mid day it would pack in
took it back to manufacturers who examined it ( stuck onto roof of camper with sikflex) with a magnifying microscope connected to a laptop and found hairline cracks inthe silver tracks that connect each cell together , they said that they had noticed an issue with supplier who made this material and had changed it
as panel warmed up so gap opened up in crack
so they gave me another which i stuck directly ontop of the old one, that failed same way so i was given a third one ( pealed 2nd one off stuck 3rd ontop of 1st )
guess what that failed by now manufacturer didnt want to know
so i had 3 flexible panels fail and all in about 7 years
now replaced with a 100watt rigid framed back contact panel from photonic universe
Fingers crossed !