Widely available are these $15 solar lanterns that you leave out to charge during the day, and they have USB connectors for charging mobile phones.

The lack of grid (or mini-grid) power is limiting for many things, but it's not a tremendous hurdle that is preventing mobile connectivity and smartphone adoption.

Could bitcoin mining help justify investment in a hydroelectric generation project? Sure. But that's not what will make or break much of anything, in the near term.