On a larger scale, there are a lot of flashing LED road signs or radar speed warning signs that aren't connected to the grid. Instead, they are powered by a sma

On a larger scale, there are a lot of flashing LED road signs or radar speed warning signs that aren't connected to the grid. Instead, they are powered by a small solar panel with a battery for at night. Even simple stop signs on wooden 4x4 posts have these. At least in my area, the speed warning signs tend to get moved to a different location a couple of times a year, and not having to run any wiring probably makes that significantly easier.