Real-Time Power Monitoring Options?

tedpearson writes "I've wanted for quite a while to be able to look at my electricity usage in graphed form, both real-time and historical data. There seem to be a number of options for power monitoring in existence: some that hook into Google PowerMeter, others to Microsoft Hohm, and some that are standalone units. I've also seen DIY projects using Arduinos for reading the data and sending it to a computer. But I haven't found anything that is quite what I'm looking for, and I am hoping the Slashdot community can give me some advice. What I'm looking for currently: Some sort of device(s) that a) accurately measures power usage, b) allows me to access the data for storage in a database for my own graphing/analysis purposes, c) will work with MacOS (doesn't require Windows), and d) doesn't cost more than $150 or so. DIY is fine, though I don't understand circuit design, which is keeping me from designing something myself."

Comments

IObridge

[rodrigo1979]

This is about as cheap as it gets for a DIY project. If I were to give you a quote for a commercial grade version you'd shoot me in the eye. http://www.iobridge.net/projects/category/projects/ http://www.iobridge.net/projects/2009/01/real-time-power-monitoring-system/

Re:IObridge

[rodrigo1979]

Here's the kind of meter we typically provide for commercial building applications: http://www.electricitymetering.com/p3894/veris_h8036_enercept.php That's just the retail cost of the meter.. add the cost of the web appliance (Honeywell/Tridium) with I/O module or Lonworks/modbus interface, plus labor to the electrician for wiring/installation, graphics design, programming the appliance and commissioning the whole enchilada. Not cheap.

Re:Watt's Up Pro

[onebadmutha]

Stick a webcam on it, do ocr to text on the numbers. Sheesh!

Reading the meter

[SIGBUS]

At the meter, you can calculate the power draw. Look for the Kh value on the meter, and count the number of seconds it takes for the disc to make one full rotation. Then, use this formula:

W = Kh / (Seconds / 3600)

to get the power draw in watts.

Of course, this assumes you're still using an old-school spinning-disc meter.

The Energy Detective

[swillden]

It's a little more expensive that what you want -- $200 rather than $150 -- but other than that, I think it's exactly what you're looking for. The gateway device itself stores sufficient data to allow you to look at short-term detailed usage and long-term trends via its web interface, but if you want more than that, you can set up something to periodically poll the device, downloading detailed, per-second, usage in an XML format. You can then store that data however you like, and mine it however you want.

There may be other solutions out there, and I'm interested to see what others suggest, but I have a TED unit and I couldn't be happier with it. It also uploads to Google PowerMeter.

http://www.theenergydetective.com

Re:The Energy Detective

[swillden]

First thing I learned after installing mine: the clothes dryer uses the most electricity by far, and leaving my computers on 24/7 doesn't use as much energy as I thought it did.

I learned the same things. The clothes dryer, stove/oven and dishwasher dominate my power consumption. A microwave is an extremely efficient way to heat food. Computers are small users, even my dual-processor Opteron file server with eight hard drives only draws about 120W. The cool "multi-can" lighting systems in my kitchen, living and family room suck a lot of juice -- each room is about 800W with the lights on. My swamp cooler uses more juice than I thought it did.

One thing I discovered the first day I installed the device was a "phantom" 400W draw that was pretty much always on. By shutting off all the circuit breakers one by one and watching the draw I was able to narrow it down and eventually discover that it was a large vent fan in my attic on a thermostat. It may have been necessary originally, but about five years ago I installed those spinning "hurricane" vents so my attic has good passive cooling -- but with that fan's thermostat set to turn the fan on at about 100 degrees, it was on nearly full-time during the summer. I turned the thermostat up to 120 and I don't think the fan has come on since. Turning it up hasn't appreciably affected the amount of time my swamp cooler runs.

So far, I think I'm saving about $20 per month since installing the TED. It should pay for itself quite handily in a year's time.

For people who do electronics

[smellsofbikes]

The Analog Designs ADE7763 is a pretty awesome chip for doing this sort of stuff. Here's the appnote in a pdf, and here's the chip itself. It's quite easily interfaced to an Arduino using SPI. I just laid out a board interfacing this to an ATMEGA1284 for doing power quality monitoring and logging, but it's for an internal project so I can't just hand out the code or layout, but it was a dead simple chip to work with: one crystal and two caps were all it required for support, and if it were interfaced to an Arduino, that could handle all the I/O to a computer or write to an SD card.

CurrentCost Envi

[Anonymous Coward]

I have an older version of the CurrentCost monitor..

When I get some extra $ together will likely upgrade.

http://www.currentcost.com/

Brultech ECM1240 is about $150 in default config

[marcmerlin]

See http://www.etherbee.com/products/ECM1240/default.htm
and see what you can output with one of those guys:
http://marc.merlins.org/perso/linuxha/post_2010-08-13_Fine-grained-house-wide-power-monitoring-with-Brultech-ECM1240_-ecmread_py-_with-net-metering-support_-and-graphing-with-cacti.html

There is one caveat: you need windows for the initial setup, although I did it in vmware, maybe it works in wine too, but since then it's been running fine on linux (and it would work just the same on MacOS since it's a python script).

Marc

TED

[Yossarian45793]

I use TED. It's right around your price range. It monitors whole-house power usage in real time and has a USB-Serial interface which you can easily suck data out of with Python script. I personally do all the data logging on a Linux box and export it through a web interface.

Re:TED

[GruntMan]

I have a TED-5000. Very happy with it. 15-minute install in the main panel; the bigger hassle was resetting all the clocks in the house afterwards. Connected the gateway device to my home network, now any device that has a web browser can see power usage. Easily accessible from the outside world by web browser, with the right router settings. Monitoring is down to the second, with a claimed accuracy of +/-2%

Nothing need be installed on the PC, and it doesn't rely on a PC to store data; the gateway device records the data and is the web server.

The manufacturer seems pretty open; they publish the XML format and there are plenty of people reading the device with PHP scripts and logging to SQL databases for more flexible & permanent data storage. There are a few iPhone apps and I think there is a Android app, or talk about one. You can export the data from the gateway in second, minute, hour, daily, or montly format, with the follow capacities:

~2 days of per-minute data
~66 minutes of per-second data
~58 days of per-hour data (likely longer... I've only had mine for 58 days!)

One caveat: the device that connects to the power panel (a pair of current clamps and a pair of voltage taps) communicates with the gateway via power line. Seems like many of the problems people have are related to power line communications, either due to electical noise or other power line communications devices (e.g. X-10) in the house. Some people have success with filters (extra cost), others never seem to solve these problems.

I think it meets the poster's requirements for a), b), and c). It cost me $243 Canadian delivered to my door in 3 days from a Canadian supplier

http://www.powermeterstore.com/p7774/ted_5000_home_energy_monitor.php

No connection to either company here. Just a very happy customer.

Re:Watt's Up Pro

[treecat]

This appears to be a re-branded product marketed by Blue Line Innovations http://bluelineinnovations.com/. I purchased one of these about three years ago for about US $200.00. It works moderately well although the meter-reading device doesn't seem too happy with New England winters.

The unit can read meters with a spinning dial and meters with a digital display. Digital meters contain an optical port through which the device monitors the meter.

The model I have can't interface with a computer; the company might have models that will do so.

Another product I purchased is produced and marketed by BrulTech Research Inc. http://www.brultech.com/. The unit is the ECM-1220 and works quite well. The supplied software is written to run under Windows, although BrulTech are very helpful in providing sample software and code for anyone who might like to port the product to another operating system.

I had marvelous plans to write some GPL'd software for OS/X and Linux; as with many projects life got in the way.

As I recall, this unit and the supplied software (not the sample code) cost me about US $300.00.

The product uses current transformers. On my 200-amp 220 VAC panel I have two current transformers - one for each leg of the load to the house.

Monitoring each load is possible with enough current transformers and host units; the cost would be (for me) prohibitive.

I strongly prefer the BrulTech unit over the Blue Line product, although each is quite usable.

Re:Overkill DIY solution...

[seanadams.com]

This is very cool! But you have a big problem unless I'm missing something. I only briefly skimmed your code so maybe I missed this, but it doesn't look like you are accounting for power factor. In order to do that you need to measure the voltage on each phase, ideally at a few KHz, and generate CT samples at the same rate which are multiplied by this measurement. This way you properly deal not only with low PF loads, but also variance and distortion in the AC line voltage supplied by the utility.

Some devices can have very low PFs, for example insteon switches and other small loads, and lightly loaded switching power supplies, it can be as little as 0.1x. A ceiling fan running at low speed, or a CFL might be something like 0.4. So the number you are calculating is properly called VA (volt-amps) and is not the same as watts, which is what you're actually consuming and being billed for.

I see you have put calibration factors in for each circuit. You may find that the reason you're needing these at all is because those loads are low PF and are reading higher than they should.