You may also consider battery “generators” such as this: ALLPOWERS Portable Power Station 300W / 288Wh Solar Generator Camping Generator with 1x100W Foldable S

You may also consider battery “generators” such as this: ALLPOWERS Portable Power Station 300W / 288Wh Solar Generator Camping Generator with 1x100W Foldable Solar Panel Included for Outdoors Camping Travel Fishing Emergency Power Supply Backup https://amzn.eu/d/aRJHhtp https://amzn.eu/d/aRJHhtp They can be charged via solar panel, although I doubt it will keep up with demand so it’s more like extending the life. You mention several days of autonomy, this could provide that if you show up with it fully charged.