I have been looking for a simple way to measure energy usage for a single appliance (in my case to check usage of an older freezer and long term measure my Heat Recovery system energy usage). Maplin are offering these Edimax Smartplugs for £25 http://www.maplin.co.uk/p/edimax-smart-plug-with-energy-usage-monitoring... (be careful to get the SP2101 as the SP1101 does not measure power).
I bought one and after a bit of fiddling and some help from a couple of folk on the NR Google group, have connected a Node-Red node http://flows.nodered.org/node/node-red-contrib-smartplug to the plug and am publishing the power usage via MQTT to EmonCMS (as a JSON <grin>).
This seems the most cost efficient and simple way of doing it.
A word of warning, the node has a couple of bugs out of the box, so while I have proved it can work, it doesn't right now!
Re: Measuring single appliance energy usage
if you can get the data directly from the device by connecting to a certain port or telnetting or something. you can write a simple application that reads the power usuage and then uses http input api to post the data to emoncms. That's what i'm doing with wemo insight switches and smart maginon plugs. The first ones are rater expensive around 50-60 euro the 2nd ones were cheap like 25 euro but not availible anymore.
I'm doing it on windows though i created 1 delphi command line app for the wemo switches and modified an opensource program named plugctl for the smart maginon plugs to send the info to emoncms. I also created an an additional delphi app to send cpu usage (of all cores) , memory and disk usuage.
I'm monitoring my intel nuc system info, 3 wemo insight switches and 4 smart maginon plugs with it in emoncms am quite happy with it :)
Re: Measuring single appliance energy usage
Hi @joyrider3774,
I wanted to avoid writing specific code if I could. Using a Node-Red Node and MQTT is (almost) an Out of the Box solution.
I looked at the WeMo but they are almost twice the price. These Edimax ones are wifi as well so no secondary receiver.
YMMV