San Diego has a large homeless population. (In some ways one wonders why more homeless people don't head to the places with the nicest weather.) There are of course as many reasons/types/explanations for the homeless people as there are homeless people, but a two very general categories are the people who live somewhere and the people who are vagrant.
The former stake out a spot. Sometimes it's a tent on a sidewalk somewhere, sometimes it's a 1970's RV or trailer parked along a street, sometimes it's in a car. I see them all the time when I ride. The cops periodically roust them (usually because camping and/or long term parking where they are is illegal) but they always come back.
Lately I've been noticing that the RV and tent homeless people are using more and more solar. They are almost always those foldable portable panels, but some use older (i.e. smaller) residential PV panels and some use the marine grade flexible panels (which are almost indestructible.) The trailer people will generally have them propped up outside against something or on the roof (identifiable by the two conductor 12-18ga zip cord coming down from the roof.) The tent people generally just prop them against their tent.
I have little doubt that these are a mix of discarded, stolen and flea-market systems; none of them look new, and many have yellowed EVA and/or cracks. And I have no idea whether they are charging a trailer battery or some other battery or just being used directly to run something. But a small amount of energy - enough to run a light at night, or run a radio, or charge a cheapo cellphone - can make a lot of difference to some of these people.
While waiting for a light down in Mission Bay I overheard two of them talking near one such setup. I didn't catch the whole conversation, but I did hear one of them say "if he's gonna charge his f*ing vape here, he's gonna pay me for it!" Which would imply that such energy might even get someone some $$.
It's taken decades for that technology to trickle down that far, but now it's started. And for someone who can't get any sort of utility service it might represent the only sort of energy available to them.