Maybe a little simplistic, but could turn out to be useful commercial product... Been working on solar powering stuff around the house, and thought it useful to have a remote meter for the output of the solar panels, and the charge condition of the batteries. Mostly to adjust the position of the panels, if not getting good exposure most of the day, and to see what the batteries are doing when I'm using the stored power.
Just something I was thinking about at work the other day, didn't work too many details, but figure I have most everything here, on hand. Microcontrollers, LCD display, wireless transmitter/receiver. Should be good enough for a passing grade, not too expensive, and you could probably sell a few units on the side.