Unless it's heating I don't think it uses much power. If you'd like I can plug mine into a kill-a-watt and see the draw. I can't imagine it's more than 100W all told, which the UPS it is connected to will run with the switches for probably a full day, and I have a specific generator for recharging UPS (a Honda with an inverter, clean enough power.)

They don't move or anything during use, and they beamform which drastically reduces the power needed. At least this is my understanding.