We did a five day backpacking trip this summer (in Wyoming, with lots of sun) and the solar was great. Kept my wife's iPhone at 80-100% for the trip (some idiot left the usb-c cable for his phone in the car) with mostly only using it after we reached camp. Decided that with two phones we had enough redundancy to leave the paper maps behind. And we used the phone a -lot- for taking photos in addition to navigation.
I've had trips where solar would have mostly failed - 11 days of nonstop rain on the Continental divide trail in Canada, to be specific - but solar has worked for me really well in CA, UT, WY, CO, etc. the places where solar would have failed were pretty obvious in advance, too.
And it doesn't take much direct sun on a 15 or 20W panel to keep two phones and a steripen charged if you're not being crazy with the use.
To make it clear, I am not saying that solar panels don't work, of course they do. What I was questioning is using a solar panel over a power bank of the same weight.
A 20 Ah (77 Wh) power bank weight about the same as a 15W solar panel. That about 3 full (0-100%) charges on a typical smartphone. I think that would have kept your wife phone up the whole trip no problem, and no need to worry about the sun.
On a 11 day trek in the sun, yes, by all means take a solar panel. However, most people I know who do such long hikes usually have access to electricity at some point. But if it is not your case, well, you are the reason why these solar panels exist ;)