I have a reader witch reads my electricity consumption from my power lines. There is a LED witch bliks and shows how much electricity I use. 1000 blinks means 1 kWh, so blinking rate will change. Would it be hard to read that wirelesly and do a graph to the server about the consumption. So we can see how much we use electricity and when.
I plan to build water meter with hall sensor. All material is at home, but I do not have time...
For electricity meter I guess every blink of impulse led means certain amount of electricity consumed. You should count impulses in known time period and then you have electricity consumption in this period. Then send this value to server.