Jeah, that's a nice tool. I have two UPS (Uninterruptible Power Supply) too, but they are so old that they don't hold for 5 minutes... They served for 45 minutes when they were new, of course depending on the consumption of course, but well, I should replace the batteries...
A solar charger for your battery would make you a king in an case of emergency. Maybe. Or it makes you a victim of being robbed. There are different scenarios/opinions if it would be clever to display "Hey, I am prepared". Maybe it could attract those who aren't. But that's another wide topic - but very interesting too!
I don't think it would bring us back to a stone age, but in the most aspects into an era of pre-industrial circumstances for a longer time. That is a very wide and also vague topic, but very interesting. I assume I will go into some aspects when I write about a second Carrington Event. Let's see if I write about... there are so many interesting topics... But this one would be really interesting and yes, I kind of promissed that in the article above...