I was thinking it would be a nice idea if you could link a sign to a generator / storage unit / machine to see its energy levels or even if its receiving power.
For the energy storage unit it could display on the sign the same numbers, ie current power out of maximum, and it could show the throughput in EU/s +/-.
For generators it could be a simple 1 or 0 for if its producing energy, or even an EU/s display.
For machines it could show also if its receiving power or if its active.
Just a thought, it would be nice if you have a lot of energy storage to see at a glance its contents, or if you have a lot of solar / water generators to see at a glance which ones producing what incase some arent being efficient...