Monitor your home’s power usage on the cheap

ir_power_meter

[Paul] was pretty sure that he and his family used a lot of electricity throughout the day. Admittedly, he enjoys his creature comforts, but was wiling to try living a little greener. The problem was, he had no idea how much electricity he was using at a given time.

While some power companies offer devices allowing homeowners to monitor their energy usage, [Paul’s] did not. After a bit of research however, he was ready to build a power monitoring system of his own. He found that his meter emits a small infrared pulse every time a watt-hour of electricity is consumed, so his system counts how many flashes occur to measure usage.

The counting circuit is pretty simple consisting of only an AVR, a resistor, a capacitor, and a phototransistor. The data is fed to a computer where the results are graphed with gnuplot.

It’s quite a useful little hack, and undoubtedly far cheaper than purchasing a whole house power monitor.

Comments

  1. andy says:

    first post, woo!
    now if only i could find a meter like that, Jim

  2. I love this hack. The new “smart meters” are being deployed here and they don’t seem to (as yet) be consumer friendly.

    This kind of hack represents the very best of hacking nature. It’s empowering to the end user, causes no damage, destruction or interference, and exploits a previously unpublished (or at least little known) functionality in a way that others in the hacker community can build in.

    Bravo.

  3. IceBrain says:

    Very simple yet useful hack, I might build one of those (thankfully, my meter is inside my house).

    500W of “background” consumption is pretty high, though, and now that even desktop motherboards can sleep there’s usually no reason to leave them on.

  4. raidscsi says:

    He is just lucky he has a new meter. Anyone think you can request a meter like this from the power company?

  5. Nick says:

    Imagine if you were able to design a sensitive system that could monitor your entire neighbourhood? There was a discussion going around the web about privacy concerns with sending consumption data off to your power company, but a hack like that could map the behaviour of many people quite easily.

  6. Strofcon says:

    Very cool! I’d be a little worried that the power company might be upset that I blocked the IR transmitter, though… seems like it would make them go back to manual meter readings, which most companies seem to be trying to avoid.

    Then again, I’m pretty ignorant of this type of stuff, and maybe he’s not actually completely blocking the signal.

    Either way, very cool idea, and seems nice and simple. :-)

    • lizaoreo says:

      Most of the smart meters transmit the data wirelessly via RF so they don’t generally come to the house once you have one installed. Of course, that could probably vary from one company to the next.

  7. Bill says:

    I would liked to have done it this way except my meter is 3 floors down, a few hundred feet away on the flip side of my building and behind a gate. That’s why I had to use current clamps instead, and it told me a lot more about my electrical system.

    http://hackaday.com/2010/12/21/clamp-sensor-power-monitoring/

  8. IceBrain says:

    @Strofcon: At least in my model, the LED that blinks for every Watt-Hour consumed is not the same that allows for actual communication with a device.
    My company still reads the numbers, though, instead of using a reader.

  9. vlad says:

    Not the first time I’ve seen this: http://www.avbrand.com/projects/powermonitor/

  10. Morgauxo says:

    I’d be a little concerned that somebody will see it and thing you are trying to slow down or reverse your meter.

  11. some guy. says:

    It’s a good device. A lot of meters have some type of IR port but be careful because some meters communicate internally within its own components over the IR port, which will cause your circuit to accumulate additional pulses. Also, not all of the meters are 1 pulse every watt-hour but the one you have is. Most residential meters are.

  12. Beef says:

    They do have commercial units that do this. They clip on the meter and watch the IR like this hack.

    This one (for about $99) uses batteries and wireless to send up the readings:

    http://www.bluelineinnovations.com/Products/PowerCost-Monitor

    I’ve worked with this one, and it’s ok. It only sends to their IHD but could be hacked to give it more useful functions.

  13. GameboyRMH says:

    It should be possible to do something similar for the old spinning disk type with just a few hardware modifications to this system. You’d just need to add an infrared transmitter LED and have it reflect light off the edge of the disc and into a receiver LED (similar to a cell phone’s IR proximity sensor). When the IR light dips, that’s the same as an IR flash on the newer models. The aiming of the transmitter and detector could be tricky, although you could look through a digital camera to make it easier.

  14. fartface says:

    If you want more accuracy and realtime load monitoring you need to move to a different scheme. that’s putting coils around your incoming lines and monitoring the load draw…

    Sadly it’s cheaper to buy the device to do this than build it….

    http://www.theenergydetective.com/ted5000-g

    I love it because the data is in XML format so I can do whatever i want with it. and I dont do the google integration. the expensive one with zigbee and the remote display is nice but a useless expense.

    Also many meters cant do the IR function. the “smart meters” they rolled out here they disable the IR output until they come to read it, which is never as it has a RF transmitter box on it.

    and yes I have needle probed their wires, no data that I can glean that is constantly sent, it only transmits when it wants to.

  15. IceBrain says:

    @fartface; why is it more accurate? Isn’t that essentially what the meter is doing?

  16. nes says:

    Great hack. And presumably far more accurate than the type which clips around a meter tail which my power company gave me.

  17. fartface says:

    @icebrain: reading it every second actual power draw. and I have never seen those pulse counting meters be 100% accurate as you cant completely shroud the meter to get rid of any light interference… a windy but sunny day can cause issues when the sun is at the right angle…

    Remember the sun is 90,000,000 more power of a IR source than the puny led in the meter.

  18. pff says:

    imagine if people just turned things off to save energy rather than pretend they are saving energy by using more energy to monitor how much energy they use and keep track of a meaningless number and fumble around their house turning things on and off while watching the number change while instead they could just look on the thing thats plugged in and read how much energy each thing uses and then know how much energy each things use or just turn things off after they are finished using the thing they were using.

    power usage monitors are a gimmick made by power companies

    these are bad and you should feel bad

  19. IceBrain says:

    @fartface: reading it more times doesn’t make it more accurate. You’re right about sun interference, though. Luckily mine is completely enclosed by a wooden “box” inside my house ;)

    @pff: this kind of monitor uses a negligible amount of energy; the chosen uP uses 0.0047kWh *per year*, probably less than what our PC, the Hackaday server and the routers in between used to post your comment.

    Not to mention that this is way more useful than simply saving energy.

  20. pgf says:

    thanks for all the comments. i certainly enjoyed building the monitor.

    @IceBrain — i agree, 500W is high. i’m working on it. :-)

    @Strofcon — meters like this also have radio capabilities. there’s no one walking up to the meter — they read it from the street, from a van.

    @vlad — thanks!! i hadn’t seen that project before. looks like he did a better job on the UI than i have. i’ll bet getting in touch with him…

    @some guy — from what i’ve read about the Itron meters, the IR led is a “Test LED”. it’s highly doubtful it pulses at anything other than its specified rate. (which as you say, is 1 w-h/pulse for mine — it’s printed on the front of the meter.)

  21. pgf says:

    btw, i think the current probe method probably is indeed more accurate for “instant” readings. having to average the pulse intervals means that there’s a 15 or more second lag until the reading catches up with reality. and of course, if you miss a pulse, you’ll be off by 1 w-h. but my installation doesn’t lose pulses due to sunlight. and certainly not wind. (“windy but sunny”???)

    @pff — i’m not sure i should feel bad about wanting to know how much power i’m using. i can absolutely guarantee that this device will save me power in the long run.

  22. Nardella says:

    You should contact your power company before attempting anything like this.

    Nice hack!

  23. pgf says:

    @texas toast — i don’t know why it got deleted. i was about to reply earlier, and then saw that it was gone. i don’t know the subtleties of “hack” vs. “mod” vs. “project”. i didn’t open the meter — that would dumb, and probably cost me fines. what i did was create a detector for the IR pulses that the meter emits, and code for interpreting and logging the results.

  24. I’ve got the same meter. It was installed after I noticed my power company had been (over) “estimating” my bill for eight months in a row.

    The new meter is read by short-haul radio when the meter reading van comes by. The old meter was read by pressing an inductive sensor up against a port on the outside wall. My actual meter is inside my garage.

    since there’s no longer a wheel that turns under the glass face, there’s a lame-ass simulation using a small LCD display, and this blinking led thing. I confirmed that it blinked by using a cell-phone camera and then “tapped” into it (outside the glass) by using a photo-diode connected to a parallel port pin. Beside that, there’s just a few simple scrips to keep track of the total blinks per day.

    I recall someone doing something similar using a laser points that was aimed at the holes in the rotating plate, but I can no longer find the link for some reason.

  25. pgf says:

    @texas — didn’t think you were bashing. the meter does contain RF, which is how the utility reads it. detecting an IR pulse is more within my skill set than reverse engineering a probably-encrypted radio protocol. :-)

  26. pgf says:

    @standard — i wish my meter was inside the garage. instead, it’s on a westward-facing wall, so most of my effort was being able to detect the pulses both in darkness and full sun.

    for people with inside meters, the job is much easier. there’s code in my git tree for using a serial port to read the pulses — if you set the baud rate right, the pulses appear as “break” conditions, and can be read as zeros from the tty.

  27. Andres says:

    Good implementation. However you should be careful with how you are touching the actual device. In Florida it is illegal to alter or mount anything permanent on the meter. You may want to make sure your solution does not violate the power company’s guidelines or your government’s rules.

    Because i knew i could not attach anything to my meter, i used a flexible PVC pipe to connect my IR sensor.
    http://andres-leon.blogspot.com/2010/02/measuring-my-electricity-consumption.html

  28. pgf says:

    @andres — i love the servo-controlled meter! i was thinking of doing something similar with a D/A converter and an old voltmeter, but the plywood and hand-drawn gauge are perfect.

    my meter’s read remotely, and the detector is only bungied to the bubble, so i’m not too worried. but your cautions are well-taken.

    i’m surprised i didn’t find your or avbrand’s projects when i was googling…

  29. Taylor Alexander says:

    @texas

    Because “this is not a hack” is an extremely tiresome argument on this website. We *know* some people may not consider something a hack, its been said 1000 times on 1000 posts. The point of this website is not to debate the use of the word ‘hack’ over and over again, its to show off neat projects that people have made and discuss them. So I don’t really blame a mod for deleting your comment if it was off topic. I totally understand you may not have realized it, but those discussions are just really annoying here.

  30. Wattvision says:

    We’re surprised no one has mentioned our product yet. This is how we started in September 2008 — and we’ve since expanded to an easy-to-set-up end to end system that anyone can get (including non-hackers).

  31. n17ikh says:

    Funny – I did exactly this a few months ago and was planning on writing it up for HAD. My IR photodiode is in a radio shack project box hooked up to an attiny85 plugged into my NSLU2 via USB with some custom code using google graphs to get me some pretty charts.
    To those talking about accuracy, this is exactly as accurate as the meter itself is. I’ve never had problems with IR noise from the sun (or the wind.. Wind causing IR? Now I’ve heard everything.) The pulse is very bright and consistent, and it is easy to filter everything else out with some simple debouncing code. The sun doesn’t cause 10ms pulses. As for being an instantaneous reading – you don’t have to average over 15 readings or anything like that, you time the interval between the last two pulses seen and you get the reading for average power over the last second, which is close enough to instantaneous for me. Accuracy using this method is as good as the timer on your microcontroller, or PC if you’re using that. Since even at very high power draws the pulse happens on the order of hundreds of milliseconds, it’s easy to time the pulse within microseconds if you want to. If you do your timing on a PC you have to deal with the fact that your operating system is probably not hard real-time but for this application the added preemption latency probably doesn’t matter.

  32. n17ikh says:

    Forgot to mention, the Black and Decker device that does this has become very cheap. If it had been its current price when I built mine, I probably wouldn’t have DIY’d.

  33. Jeditalian says:

    i would occasionally stroll up to your meter and press a few buttons on a universal remote to make you shit your pants.

  34. cmholm says:

    My analog meter was recently swapped out for a digital model, so I’ll do a bit of recon to see if this hack might work for me.

    Allowing my imagination to go overboard for a moment: I’m wondering if a currently unused Axis webcam and remote OCR might be able to reliably pull it off? One issue would be the need for nighttime illumination (IR or visible), and preventing glare.

  35. Andrew says:

    After testing this, my meter emits the same IR pulse every kilowatt hour. But after loading a simple IR reader on my Arduino at each pulse it sends the value on the display of the meter.

  36. CameronSS says:

    I mounted a commercial version of this on my power meter — hose clamp attached it to the glass bell, and an arm reached around front and watched for the black stripe on the spinning disk. It worked brilliantly until someone from the power company spotted it and demanded removal. At that point it became a “hazard” and a “barrier” to any of their people if they needed to get to the meter. Because we trust these people with high voltage but not with a flathead screwdriver?

  37. geeknizer says:

    O yeah, bring it on

  38. jukus says:

    @pff you can’t manage what your not measuring

  39. jukus says:

    I tried this simple approach too works a treat. Phase 2 – hack a cheap wireless doorbell into it for wireless monitoring to a(eth-sheilded)arduino that runs my x10 network.

  40. ZeUs says:

    Why would it send an IR signal? Weird.

    Neat trick though.

  41. pgf says:

    @n17ikh — re: accuracy — there will always be some delay when using the pulses to measure consumption. that delay isn’t present with current probes. but i agree that for real-world use, using the pulses is completely accurate enough.

    i will say that either my meter puts out weaker pulses than normal, or my phototransistor is the wrong one — i wouldn’t call my pulse “bright” in terms of the edge levels i’m seeing.

  42. pgf says:

    @Jeditalian – not all IR signals are created equal. your IR remote wouldn’t have any effect on this detector.

  43. pgf says:

    @Andrew — i’m not sure i understand what you mean.

  44. pgf says:

    @Wattvision — perhaps no one has mentioned it because your product costs $250, and involves a $9/month service fee. i’m planning on writing a blog post about other power monitoring alternatives, and will probably include some commercial links. i’ll be sure and mention that you spammed these comments. ;-)

  45. Bharath Kishore says:

    In India we have power meters that have a rotary disc. It has a marking to know it’s in motion and at any point of time it’s angular velocity is directly proportional to the amount of power consumed at that instant. A stop watch, pen and paper would do the trick for me.

  46. pgf says:

    @bharath — we have those meters in the US, too. it’s only in the last 5 or 10 years that some areas have switched to fully electronic meters. the reason is that they can be read remotely, without someone needing to walk up to the meter to read it.

    pen and paper would work, of course, but you’d be standing at the meter a lot in order to make logs. :-)

    here’s a project where someone is attemhttp://letsmakerobots.com/node/23875pting to automate reading a meter like yours:

  47. pgf says:

    oops. pasted in the middle. that URL should be:
    http://letsmakerobots.com/node/23875

  48. pgf says:

    i’ve added a new blog post at the irmetermon project page listing many of the similar projects mentioned here, and others i’d found earlier. please add more in the comments on that page — it’d be good to have a more complete list.

    -paul

  49. John L. says:

    I did something similar to this for my water meter. I used a pic processor and an xbee transmitter to send the info to my pc. I used google charting software to display the data.
    Checkout http;//watermeter.limewebs.com

    I count the revolutions of the magnet inside the water meter. With an IR sensor, I should be able to use the same hardware on my XCEL energy power meter.

    Charts for water usage are at

    http://watermeter.limewebs.com/html/may.html

  50. Sean says:

    I might go back and try the spinning disk method, didn’t even consider measuring the rate of change. Reading the dials wasn’t going well for my electricity meter, but for a better-behaved water meter in a dark cupboard, ‘reading’ the numbers worked OK:

    http://firtl.com/2013/04/25/read-gas-water-electricity-meter-with-webcam/

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 92,108 other followers