

Right, but it also depends on the application. It would definitely be enough for charging your phone a whole day at a festival. I’ve been using one of those “hiking” panels that you can put on a backpack. It is rated at 15 W, but I get less than 5 W out of it, which is still enough for charging my phone and not having to use a powerbank for the whole duration of the festival week; if it is sunny that is. I would love not having to bring both, an umbrella and the solar panel. E.g. Hellfest this year really was hot as hell, it definitely would have worked for this application.
But folding and weight would be a problem, and I don’t see it useful for any other scenarios. (E.g. at the beach or other one-day-events you just charge your phone at home/hotel and can use it the whole day.)
Only if you’re naked.