Off-grid systems appear to be all the rage now, with more and more companies advertising and selling portable battery power stations and solar/wind generators. However, the idea isn't exactly new. Off-grid power by solar, wind and sometimes hydro, is used in remote areas for decades now. But lately, improvements in battery tech made it more economically viable to make batteries you can cart around with ease, that pack plenty of power to get you through a day. However, there's still the economy of scale. Small scale solutions are comparatively expensive, even more so where mains electricity is comparatively cheap. That's why small scale generation isn't really a thing in places, where mains grid is available. Experimental or DIY solutions aside, of course. But on a larger scale it's a different story. Usually power generation and storage gets cheaper per unit when scaled up.

Recently, Australia disconnected remote areas from the power grid and replaced it with power stations powered by solar and wind generators. They claim that due to the long and maintenance intensive power lines, this would help cut costs. Reliability does not seem to be a problem there.