Solar charging seems like a good idea at first, but has a number of really serious disadvantages that make it absolutely a waste of time and energy and money when preparing for life on the road as a DNB.
Solar charging is only fast if you have 200w+ or more of input on a perfect sunny day. In such conditions a panel will charge something like a Jackery 1000 Explorer Pro in 4.5 hours. Plugging that same power station into an AC outlet will do it in 1.6 hours. Three hours is a lot of time to lose every day as a DNB when fitting work and bike touring into the day is already challenging.
And that is for one thing at a time. Compared to even a 4x65w fast charger it is still slower since for fast-chargeable devices can all be charged at the same time. This is simply not possible with any solar approach short of carrying four different, massive solar panels.
My 250w Jackery SolarSaga weighs 22 lbs. That is almost as much as the 32 lbs power station itself. In bike touring weight terms, that is a ridiculous amount. Some people try to fit all their gear under 40 lbs.
Rather than lug around a heavy solar panel, I carry a slightly heavier charger for those battery bricks and have bricks that can be charged at least at 65w but perhaps even more. When planned right, the stop to recharge can be less time than it takes to check it at work and grab a coffee from the local diner or cafe—especially when following a “top off” strategy.
People who attempt to have their solar panels work while biking usually end up pulling a very heavy trailer. No thank you. Even then the rotation is never idea and the amount of watts way too small, if there is even enough sun.
I never want to be more than three days (two nights) away from a power source. This is roughly the same for water and food. Getting that far off the grid is a significant distance, the entire length of Moab’s White Rim trail, for example. The GDNBR has two at most between resupply checkpoints (which almost always have power as well).
Based on this maximum time between resupply, which has been codified into most all trail guides and adventure cycling routes, I never actually need to pull out the solar panels at all.