DIY household power use monitor / logger

[MetroMPG]

Stumbled across this project - a home made logger of household power use (think: heavy duty killawatt that monitors the whole house instead of just one plug).

An AVR-based logging wattmeter

This device monitors household power usage and logs it to an SD card. A simple analog front-end amplifies the signals from voltage and current detectors and an ATmega168 microcontroller computes the power consumption using the formula P=V*I. The voltage and current are each sampled at 9615 Hz so the integration should be fairly accurate even for highly non-sinusoidal loads such as computers or fluorescent bulbs.

A bit out of my league, but probably not for some others here.


A strip chart showing power usage over time.
Our hot water heater uses over 4kW.