I do some non-biking trips (kayak or canoe) of up to two weeks long without any form of resupply. Thus, my dynohub option does not work on those trips. And my backpacking trips always have re-supply after no more than six days.
I reassessed solar a few months ago after looking at what Happy Feet was doing. But in my reassessment, I concluded that carrying batteries (in my case mostly AA, not very much Li Ion) was less weight than the weight of solar. And if I am not searching out sunlight, the batteries were more convenient.
I just finished a week and a half long backpacking trip last week, that involved re-supply for food after no more than four day long segments, each resupply of food also included four more AA batteries for my GPS and headlamp, and camera batteries (Li Ion). My phone was either off or airplane mode except a few minutes per day, I carried three phone batteries (an LG phone that has user replaceable batteries), and never needed to change one.
A quick note on Li Ion batteries, if at all possible you should minimize using cold batteries. I learned on my Canadian Maritimes trip two years ago that using my phone for just a few minutes to get weather forecasts and check e-mail with a cold battery in the morning could consume 10 percent of my battery. After that I always warmed up my phone, either in sleeping bag or in a pocket under my down vest before I used it which greatly extended battery life.
I recently learned that my favorite AA and AAA batteries that were Ikea Ladda white NiMH rechargeables have been replaced with different models. I have plenty off the white ones, but I am no longer suggesting any particular brands for purchase, as I have no experience with their replacements.
At this thread if you start at post 53, you find a "conversation" between me and Happy Feet. There may be some useful info for you there.
https://www.bikeforums.net/touring/1...choices-3.html
***
For touring, I use a powerbank with 44 watt hour rating, that powerbank will work in pass through mode, meaning it can be charged simultaneously with being discharged to charge up a USB device. My powerbank is no longer made, the company makes bigger and smaller ones. They cost more than many others, but I am sold on them, brand is Voltaic. If you had their smaller one, you could go for a long time with cloudy sky if you were relying on solar.
https://voltaicsystems.com/battery-packs