Hi all,
I've been busy of late, so not been tinkering in the shed as much as usual, but something came up the other day.
I had a solar panel salesman round, selling a system to generate electricity (I'd be quids in, apparently
).
As part of his speil, he looked at my electricity bill, and sucked through his teeth, saying how high it was. Salesman patter to make you want to reduce it by buying something that he just happens to be selling. But actually, I did think it was high, and it did make me want to do something about it.
For a few years I've had one of those electricity monitors that sit on a table or shelf. It's got an LCD screen, and there's a wireless sensor that you clamp around the live cable going into your fuse box. The remote display then shows you how many watts you're using in realtime, and also draws a very basic graph and some stats. I got it for free from British Gas a few years ago.
But watching the numbers jump about isn't that useful, what I'd like to do is plot them.
Turns out this is rather easy to do, with a Raspberry Pi and a ready-produced setup to do just that.
The energy monitor (mine is a Current Cost model 128) has an RJ12 serial port on the back which spews out data! I bought a data cable for it off ebay that has a USB adaptor at the other end.
You can download a ready-to-use Raspberry Pi image from here
http://lalelunet.github.io/measureit/ which has the MeasureIt software already installed, plug the Raspberry Pi into the energy monitor, switch it all on and off it goes.
The software records all the data in an SQL database, and you can view the graphs and configure it through it's web interface - just point your browser at the ip address of the Raspberry Pi.
It's all rather neat, and I'm very impressed.
I've attached a graph plot for this evening, you can easily see the moment I switched the electric heater off in the shed and came indoors, and you can also see there's quite a high background consumption going on that needs to be looked at.
I thought I'd share this with you all here as I'm fascinated by it all, and I know others here like plotting DSL line data, now you can plot other things too, and chase around trying to improve the graph
Ian
[EDIT : On the graph, the left hand vertical scale is Watts, and horizontal scale is time (GMT)]