It's nice to plot your daily electricity usage so you can see places for conservation. The utility meter on your house
records cumulative kilowatt hours used since it was installed. The number of watts being used is even more helpful.
There are different methods to capture this information. One approach is to put current measurement coils on the main
leads to your breaker panel. One of the most well known products is the
TED The Energy Detective.
The advantage is that you have more resolution than the utility meter reports.
The downside is that the computed kilowatt hours
may be different from what the Power company's meter says. Another approach is to
read the 1 watt IR pulses on the
meter. This has nice resolution, but if the system misses any pulses, you loose track of your total usage.
The other downside is that you have to mount something on the meter outside in the elements. Sometimes alignment can
be a problem. A commercial example would be the
Blue line Energy Monitor
There are several Internet sites that you can post your power usage to. Google launched the
Google PowerMeter Project
as a free energy monitoring tool to raise awareness about the importance of giving people access to their
energy information. Unfortunately they retired the service in September 16, 2011.
Microsoft had the
Hohm Power Service
but it will be discontinued on May 31, 2012.
There are several other sites that have picked up the slack:
A third approach has been developed by
It uses the Consumption data packets that are broadcast by many ERT utility meters
manufactured by GE, Schlumberger, Itron, and others. The Grid Insight AMRUSB-1
has a pretty good range. It will pick up meters within several hundred feet.
You will need to identify your meter by the number on the front of the meter as shown above.
I didn't want to keep a desktop or laptop computer tied up reading the utility meter.
The ethernet connected open-hardware
seemed like a good fit.
Sparkfun has a USB Host Shield available, but it needs to be modified:
Cut the USB Host Shield PCB trace going to IO pin 10
Wire the PCB trace thru small hole to pin 6
Jumper RST pin to Pin 7
Connect 9VDC power supply to the arduino. The USB power is not sufficient enough!
Other types of real-time data have sites that users can share their data with the global
Internet Community. For example,
is a great place to store my weatherstation data.
StrikeStar is wonderful for processing
distributed lightning detectors data to produce real-time maps.
Pachube ("patch-bay") connects people to devices, applications,
and the Internet of Things.
As a web-based service built to manage the world's real-time data,
Pachube gives people the power to share, collaborate,
and make use of information generated from the world around them.
This is a perfect repository for our
House Electricity Usage data.
It provides a simple HTTP interface to post data and applications which generate charts that can be
included on your web pages:
This project is for experimental use only.
The user assumes all responsibilities for assembly, installation, and use.
This circuit is provided without warranty and the author makes no claim that
this device will work in any particular application.
Do not use in applications where failure or incorrect operation could jeopardize
someone's safety. This schematic is provided for noncommercial use only.