I'm a survivalist & technology nut.
Wherever I go, I have a bag with whatever I need to get by for a few days completely unaided.
For solar electricity, I use Goal Zero products. (The number designations are approximate watts or watt/hours as appropriate.)
My smallest bag includes a Nomad 7 solar panel and Guide 10+ 4-AA battery pack. Charges in 3-5 hours direct sunlight, in turn charges an iPhone 6S 1.5 times. Also can charge flashlight, Watch, and a few other tiny gadgets.
My office bag includes a Nomad 20 panel and Sherpa 100 battery with inverter. Charges with around 8 hours full sun, in turn battery runs a MacBook Pro about 5 hours, whose own battery then lasts another 6+.
When traveling by car, I take a Boulder 100 folding panel and Yeti 400 battery with inverter. Charges battery in about 8 hours, and can run the MacBook completely from direct solar. Have cell signal, work anywhere.
I've also had an electric car for 2 years, and investigated the Tesla Solar Roof.
Having experimented with all that for years, my take on the Caviar Tesla iPhone X for >$4000 is: what a waste of resources, and an insult to the Tesla brand. For $100 you can get the Guide 10+ & Nomad 7 kit at
https://www.goalzero.com/shop/solar-kits/guide-10-plus-nomad-7-plus-kit/ with far more capability, still small enough to keep handy without permanently bolting it to the phone.