I'm only half kidding. I'm a bit of a prepper and I have lots of powerbanks and devices that charge from USB but besides idling my truck I really had no other way to charge any of them in case of a long-term power outage which seemed a bit of an oversight on my part.
Not like this solves the issue. 30 watts (under ideal conditions) isn't much but it's a start.
30w is plenty to run a few small lights and phone chargers. You can cook over a wood fire if necessary, or store food that doesn't need cooking.
Kinda curious now what the back to reasonable normality for essential needs time is for most disasters. Don't need to stockpile enough to last until completely rebuilt, if food supplies are going to be restored fairly quickly but housing takes a year you don't need the full years food supply.