DIY Energy Monitor Mounts To Your Electric Meter
This DIY solution uses a small breakout box with an IR sensor that senses an IR light that flashes when you’ve used a kilowatt hour of electricity. You could also retrofit this to work with older boxes using a light that is interrupted as the disk inside the meter spins. The sensor can tell how often the beam is interrupted and transmit that data to a computer or other device.
the box holds some minimal electronics (14 pin AVR micro, a resistor, a capacitor, and a phototransistor), the piece of rubber shades the meter, and the bungee cord holds it all together in a most attractive way. okay, i was kidding about the last part.