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."

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/ [iobridge.net] http://www.iobridge.net/projects/2009/01/real-time-power-monitoring-system/ [iobridge.net]

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

Google Power Meter / Hackaday Suggestions

[SheeEttin]

If all you want is graphing, then Google Power Meter is probably the best way.

That said, there have been a few articles on Hackaday recently [hackaday.com] concerning methods of interfacing meters with Google's API. I assume that once you submit it, you can get it back out.

Or, if that doesn't do it for you, I'm sure you could adapt one of the projects on Hackaday to your own ends.

Flukso looks interesting...

[mspohr]

This product is designed for whole house real time monitoring with the results available on the web... looks interesting.

http://www.flukso.net/ [flukso.net]

Your budget isn't realistic

[dave562]

Take a look at what a monitored PDU costs for a server rack. APC offers them, as do a few other vendors. You're easily looking at $450 per PDU. It will do everything that you want though, including output to SNMP so that you can trap it.

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 [analog.com], and here's the chip itself [analog.com]. 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.

Most meters can monitored optically

[Anonymous Coward]

See here for a commercial product that exploits this:

http://www.blackanddecker.com/energy/PowerMonitorCompatibility.htm

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 [etherbee.com]
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 [merlins.org]

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 [theenergydetective.com]. 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:IObridge

[rodrigo1979]

Here's the kind of meter we typically provide for commercial building applications: http://www.electricitymetering.com/p3894/veris_h8036_enercept.php [electricitymetering.com] 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.

Maybe currentcost

[Booker]

The currentcost meters are fairly cheap, OSX-capable I think, and very popular in Europe so there are lots of little scripts for them. In the us you can find them at http://currentcost.net/buynowmain.html [currentcost.net]

The DIY rig at http://openenegymonitor.org/ [openenegymonitor.org] is fairly straightforward, even if you're not that technically inclined....

Otherwise I'd just echo the suggestion to suck it up for the extra $50 and get the Ted 5000

My recent time-waster is finding a way to make all these different gadgets able to talk to all the various websites [sandeen.net] ...

Re:The Energy Detective

[Stele]

Yep, absolutely fantastic system and not too hard to install yourself. The wireless receiver actually has a built-in web server you can log into from any computer, and "there's an app for that" too. You log into the server, tell it what your energy rates are, and it'll tell you instantly what the electricity is costing you. I have mine sending everything to Google PowerMeter (this feature is built in) which provides very accurate persistent usage data.

I sprung for the optional remote which sits in our kitchen and displays our usage all the time.

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.

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.

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 [powermeterstore.com]

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

I've built my own

[baileydau]

In conjunction with getting solar power at home, I've also set up real time usage monitoring.

I've had a stand alone power monitor for a while (our state Government offered them + a bunch of CFLs and other stuff for $50). However it doesn't have any PC connectivity. One day I was looking in the meter box, and I realised that the sensor was just a clamp meter around the input wires.

I already had a clamp current meter attachment for my multimeter (which also has RS232 out), so I put the clamp around the same incomming wires, connected it to my multimeter and then to my PC (via an RS232 -> USB cable). From there I have some scripts to take readings and enter them into a database as well as a web interface for output. Fortunately for me, the meter box is just outside of the room where the PCs are, so it was easy to wire up.

I actually did this setup in a number of stages. Initially, I used some software for my multimeter to plot / save to text file the raw (amperage ) data. I then started batch importing it into the database and calculating wattages etc from there. Now it all happens automatically. Readings are taken at 1 minute intervals.

Even though I already had all the parts, they cost well under your budget. From memory their original costs were:

    * clamp meter attachment (Digitek QM1565) $25 (see http://www.jaycar.com.au/productResults.asp?keywords=QM1565&keyform=KEYWORD&SUBMIT.x=0&SUBMIT.y=0 [jaycar.com.au])
    * multimeter with RS232 (Digitek QM1538) $50 (NB. this model is no longer available, don't know what an equivalent would be)
    * RS232 -> USB $6 (from eBay)

Now I live in Australia, so your meter box setup may be different to ours. In mine, the meter and circuit breakers etc are mounted on a board in the box. This board has hinges on one side, so you can swing it out to get behind it. That's where the wires are that you need to put the clamp around. Obviously you want to be very careful back there, but there *shouldn't* be any bare wires etc. If in doubt, you could get an electrician to do this for you.

I've put a sample of our median usage and production on Imageshack http://img31.imageshack.us/i/electricityusageandprod.png/ [imageshack.us]

Here is the usage and production for a single day http://img163.imageshack.us/i/usageprodction20100915.png/ [imageshack.us]

Having this type of data is great for tracking down where your usage is going.

Re:Watt's Up Pro

[treecat]

This appears to be a re-branded product marketed by Blue Line Innovations http://bluelineinnovations.com/ [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/ [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.

Re:Overkill DIY solution...

[seanadams.com]

Ehh.. never mind. I see you are using ADE7753 which watches the line voltage.

Re:For people who do electronics

[smellsofbikes]

A few thoughts: the ADE7763 I mentioned is nice because it's so cheap, and a board built around it would cost about $5, with roughly $8 of components (chip, crystal, screw terminals, header for the SPI bus) so you could afford an Arduino and a half-dozen of these, and put them in the breaker box to measure multiple circuits simultaneously. But if you want to go appliance-by-appliance, the bus length and the per-unit cost are going to get very painful, and it seems like the tweet-a-watt kit [hackaday.com], using a cut-up kill-a-watt meter with networking added, would be a better idea. Of course, that doesn't work with 220V appliances, and you have to get something like the SmartWatt [smart-works.com], which isn't as user-friendly, although it does come with networking built in. It's also $20 over the article's price budget, which is a shame because it's pretty cool.

But if you're a serious DIY person, I think that analog chip is going to be hard to beat.

At work I use a Yokogawa WT210, and it's fantastic -- distortion out to the 50th harmonic, scads of power factor and real power measuring abilities -- but it's also like $7K, and a bear to learn to use. Le sigh.

With all THAT said, I don't know of any accurate, networkable, completely non-intrusive load monitoring hardware, which is a shame.

Re:Tweet-A-Watt

[nospam007]

I found an energy-logger from Conrad.de in Germany.
It has an SD card where it stores the data for 6 months. Apparently it includes software to graph the results. Around 60 bucks, cheaper if you buy several.

http://www.conrad.de/ce/de/product/125335/VOLTCRAFT-ENERGY-LOGGER-4000-ENERGIEKME;jsessionid=7CBBF03B9C5D056C0E5E07A4CDEFCC77.ASTPCCP4 [conrad.de]