12.15.08
Monitoring Home Electricity Usage Using Current Cost
After reading an article over on AutomatedHome the other day, I decided to go ahead and order a Current Cost (CC) system for monitoring our own home electricity usage.
I ordered via their eBay shop, and the package arrived the next morning! Installation was a breeze: just pair the display unit with the sensor (for the wireless communication), attach the sensor ring around one of the main cables feeding electricity into your house, and away it goes! Once the basics were up and running it was time for the fun part: connecting it to a PC! This feature was the main reason I went with CC over the other units. The connection is made using a standard RJ-45 cable via a port on the display unit. Using a serial-to-USB cable I’ve connected it to my Linksys NSLU. Like most people, when I first got the NSLU (AKA the slug) I flashed it and installed an alternative Linux OS (SlugOS/BE). This allows you to then use the slug for just about anything you want from a networked PC. In my case I installed TwonkyMedia to turn it into a nice little UPnP AV server, storing files and serving photos and music to a digital photo frame and the PS3. But I digress. So with the CC connected to one of the slug’s USB ports I just had to write a little python script to parse the data, which the CC spits out in XML format every few seconds. Rich Cumbers has been kind enough to document a description of the XML format, which made it easy to identify the bits I needed.
Now on to the data consumption! When I started looking into the whole CurrentCost thing I stumbled across a new site called Pachube, “a service that enables you to connect, tag and share real time sensor data from objects, devices, buildings and environments around the world.” There are already quite a few interesting feeds set up on the site, such as the UK’s electricity usage, an automatic weather station in the Ross sea, and a musical swing in a Swedish park, as well as several current cost feeds, as well as my own. The service also allows you to generate a dynamic image for various feeds, so here’s mine:
Now to start adding more sensors to the house. I’m sure Hanne will be pleased! 