>>543382Only works in the sun (and even then, i'm not impressed with the one I have).
Biolite works at night too.
Neither really offer a lot of power though.
My opinion as an engineer.... for a week or so innawoods, get a 18650 USB charger ($20-ish on amazon) and a handful of NCR18650B (3400mAh) batteries ($40-ish for a 4-pack), start the trip with a full charge and be mindful of your power consumption.
For 12v/automotive power, you can buy lithium powersports/lawn-garden batteries that weigh a lot less than a standard Pb-Acid/AGM battery and offer greater charge capacity. Since the charge controller and battery management's built into the battery, you can recharge it easily off any automotive source.
>pic kinda relatedIf you're going totally off-the-grid for more than a week or two (see
>>543207), sure, start looking at other alternatives like PV or TEG.
It's mostly a gimmick though.