I've done two installations of flexible solar panels on a vehicle and done tests of all the flexible solar panel types that I know of GaAs, Unisolar types, trad thin film, Mono or Poly under PET and ETFE. My takeaway is the fancy types, Unisolar, GaAs, ETFE , are really good but the ETFE Mono or Sunpower are easily twice as efficient as the others and probably half the price. GaAs also loses efficiency off axis more readily. PET is rubbish. I've always liked Unisolar panels even tho' they are so inefficient because of the inventor and the history https://en.wikipedia.org/wiki/Energy_Conversion_Devices
Had a great experience with ETFE Mono on a metal vehicle over a couple of years with no output loss on the roof directly mounted with Polyurethane glue with no obvious problem..
However, this slightly alarming below. We are looking at going with a 3M product dual lock
for our smaller solar panels 50w on a fibreglass roof. Hopefully the distance between the smaller panels will offset the heat compared the 150w panels.
Our new Winnebago ILUKA motorhome that we took delivery of in November 2020 was fitted with a 150 watt semi flexible panel in the factory. On hot days the heat generated dropped the charge rate by about 50% and the heat being transferred to the fibreglass / foam sandwich roof structure was alarming.
By the way I'm getting my ETFE panels at a rate that's less expensive than those prices listed. Suggest looking around.