Using "off-the-shelf hardware", we have modified a Kill-a-Watt(TM) power meter to "tweet" (publish wirelessly) the daily KWH consumed to the user's Twitter account (Cumulative Killowatt-hours). We are releasing this project as an "Open source hardware" project - in other words, anyone can make these, modify them and make a commercial product from the ideas and methods.This was the winner of the Greener Gadgets Design Competition. Twitter feed here. Instructions on how to make your own here.
Here's how it works: The modified Kill-a-Watt uses a "super-cap" to slowly recharge itself. Once there is enough power it turns on the Xbee wireless module which transmits the data to a nearby computer (or internet connected microcontroller, like an Arduino). Once the power usage for the day is recorded it uses a predefined Twitter account (it can be your own) to publish your daily KWH consumption for the day. Multiple units can be used for an entire household.
I think this is a very cool concept. This allows people to continuously monitor their electricity consumption wirelessly on the web. Unlike other solutions it does not require access to the power meter or the breaker panel (which is great for people who live in apartments). You could see how this could easily be modified to use something like Google's PowerMeter rather than Twitter for better analysis of the data.
I have some ideas on how the design could be tweaked to make a very appealing consumer product, but I will save that for another post.
via Core77 via Engadget