I think the flexible panel technology is not "there" yet!
Although several different brands of rigid framed-glass PV panels are good (Panasonic HIT series are the best),
There are probably only two manufacturers of reliable flexible PV panels: SunPower (now Maxeon*),
and
Sol-Go (formed by former SunPower employees).
bosswatt.com is a good source (but not the only source) for both.
The attached image shows the difference in the cells themselves, but there's more to it than that. Most of the flexible PV panels produced in China are produced essentially by hand using mostly basic processes imilar to what is used in sign-making, using layers of laminated film. Phrases like "Japan-imported ETFE" are promoted as evidence of better quality than less expensive panels, and although it's true that ETFE has better UV resistance than cheaper laminate films, that also confirms that panels are made via that basic lamination process, which can eventually lead to moisture infiltration due to de-lamination. I think there are some other drawbacks to this method of construction. Even when they use Sunpower's Maxeon cells, the overall panel reliability is not that great.
SunPower flexible panels are made in a high-tech automated factory in France (yeah, seriously).
Sol-Go are made in a similar factory (in the Phillipines, I think).
There *may* be some Chinese-produced PV flexible panels that are close to the quality of SunPower's panels, but I have no idea which Chinese brand that might be (if any).
Also, the most often overlooked but really important factor in a PV panel is the Power Temp Coefficient, which is the measure of how much the power output declines with increasing temperature above 25°C (and actual operating temperature in the summer is usually more than twice that). SunPower's 2018+ flex panels have only -0.30%/°C (power output declines 0.3% per °C above 25°C), which is lower power loss than any other panel besides Sunpower's rigid panels and the Panasonic HIT series. This brings up the other aspect of the problem: it's great that flexible PV panels can conform to curved surfaces... but in hot weather, that also usually makes them operate at an even higher temperature than if they had ventilation on the underside. The best way to mount these is on a hinge, so that they can be raised up to the proper solar incidence angle, and provide ventilation too. I know that a lot of people put rigid PV panels on top of an RV, but I would not put that much weight up there, and the only flex panels I trust are Sunpower & SolGo.
You can buy a 50-watt version one of their slightly older series (same build quality as newest 110-watt version, but half the size & slightly lower output cells) on
ebay for about $84 or
on Amazon.
Use it to maintain a lead-acid SLI battery and/or put it on your roof of your house for a couple years and see how well it's still working then.
*
SunPower split off its manufacturing division last year (now named "Maxeon" which previously was just the brand name of their cells), and they unfortunately also eliminated their US distribution center, which is now located in Mexico. That doesn't matter too much if buying a few panels for individual use, and the cost had been dropping anyway until the recent shortages of everything reversed that trend. Last quote I got for the 110-watt SPR-110 was $86.90 each in pallets of 32. But it costs almost $350 just to get one pallet across the Mexico border, and then they have to be shipped.
