Efergy e2 Review

In the box
The efergy e2 is a wireless electricty usage monitor that allows you to track how much power you are using and have used over time. In the box is a sensor, which clips around the main electricty supply cable into your home. The sensor plugs into a transmitter, which sends a signal to the receiver and display unit.

Additional sensors are available seperately, should you wish to monitor more than one power supply or a 3-phase supply. The unit transmits information using the frequency of 433.52MHz and the claimed range is in excess of 40m. It claims to measure current in the range 50mA to 85A, with an accuracy better than 90%. This level of accuracy doesn't sound brilliant but in reality, it is good enough.

Installation

Installation of the transmitter module involves inserting three AAA batteries (not supplied) and clipping the wired sensor around the main cable into the mains distribution board. This sensor has a 3.5mm jack plug and simply plugs into the transmitter module.

Installation of the receiver/display module involves inserting three AA batteries (not supplied) into it and some simple configuration to set the time and date. You can also configure CO2 and electricity tariffs and prices to get other usage data. Reception appears good regardless of where the display module is placed in the house. Response time to switching new devices on or off is quick, with the display updating in around two seconds or less.

On the back of the receiver is a time set / alarm button. You can set an alarm level and if the instant power usage exceeds this level, an audible alarm sounds for about 10 seconds. We set this 4KW and sure enough the use of two ovens was enough to activate the alarm. Also on the back is a flexible plastic cover, behind which is the micro-USB port and a socket to enable use of a 6V dc PSU.

Software

The box contains a CD with the eLink software. Our supplied CD was corrupted but you can down load the software from the product support page. The software installs a USB to serial link driver and an applications. The application asks you a few questions about tariffs and enables you to download data from the e2 device.

The device and software support a two-tiered tariff, where you pay one price up to a defined amount of power used and another from then on. There is no mention of standing charges.

Features

Instant power usage
The main figure of value is the instant power usage reading. The function 'fn' button on the top of the display unit also allows you to cycle through instant power usage, average daily usage and today's usage. Whilst viewing the average daily usage figure, you can use the up and down buttons to run through the previous days. The mode button cycles through power, CO2 generation and price paid.

Instant power usage
The software allows you to download the data from the display unit to your PC, using the supplied USB lead. It provides different views of your energy usage and allows you to see how it varies throughout the day. You can also track usage over the course of a month or year.

Instant power usage
Another view is a 'consumption curve' which provides a view of how you use electricity of the course of each day of the week.

The software allows you to backup the data to your local disk. This generates a Microsoft Excel spreadsheet and an XML report. From these files it is possible to extract the hourly electricity usage and thus the daily, monthly and yearly usage figures. This is discussed and covered in more detail in the design and monitoring section.

Summary

For the money this device is very good. It meets its primary purpose very well and provides a clear and accurate view of instantaneous power usage. The software allows you to track usage down to an hourly level and records data over many days.

Likes

  • Easy to install and configure.
  • Well constructed and easy to use.
  • Portable display can be placed anywhere in the house.

Dislikes

  • None really. Does what we expected and does it well. Would be nice to get more technical details.
  • Would also be nice to be able to export the data more easily to other applications.

Updates

You don't expect us to leave it there do you? We are currently looking at ways to interface our Home Control System (HCS) to this device and to export the data in other formats. Watch this space for updates soon ...

Some interesting figures stats have been collected with this unit. Through the night, our house idles along using about 200W of power. This is mainly the fridge/freezer and a few other electrical items left on such as the BT Vision PVR (which has no proper standby), Mini-ITX PC (our Home Control System (HCS)), etc.

The USB to serial port interface operates at 9600 baud with 8 data bits, no parity, 1 stop bit and no flow control.

14th Jan 2010

On connection to a PC via a USB port, the device downloads data so that it can be displayed within the application. One option with the application is to backup the data collected from this device. The generates a number of files and one of them one my machine is a CSV file called #001.csv. You can open this file with Microsoft Excel and view the data within it.

We produced our own spreadsheet into which the daily data from this CSV file can easily be copied and pasted, to provide a monthly/yearly archive of the usage data and makes it easier to view and analyse.

14th Feb 2010

Did some checking of this devices accuracy by taking meter readings on 26th Dec 2009 at 12 noon and again on 31st Jan 2010 at 11pm. This showed we had used 467.79KWh over this time period. We then totted up the hourly measurements made by the Efergy e2 over this same period and it came to 456.80KWh. That makes it pretty accurate!

16th Feb 2010

Did some checking of this devices accuracy by taking meter readings on 26th Dec 2009 at 12 noon and again on 31st Jan 2010 at 11pm. This showed we had used 467.79KWh over this time period. We then totted up the hourly measurements made by the Efergy e2 over this same period and it came to 456.80KWh. That makes it pretty accurate!

1st Feb 2012

This device is still going strong and we still find it useful but, we can no longer be bothered to connect it to our PC to get the data off of it. We are now looking for a similar device which uses wireless networking and probably Z-Wave technology.

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