Open Energy Monitor

[Bulah Landaker]

Iam running both openHAB and EmonCMS on local servers. I have an Arduino Uno + Ethernet Shielf + EmonTx Shield running a modified version of their monitoring sketch which publishes the readings using MQTT over ethernet.

I then have openHAB configured to subscribe to those topics and thus have all my energy readings/data available for use in rules etc. I also have openHAB setup to store these readings in my InfluxDB timestore (via the persistence binding), I run Grafana on top of the InfluxDB to provide the pretty dashboards and graphs.

So in short, the EmonTx (on the Arduino) measures my electricity feeds etc, and publishes to a set of MQTT topics. openHAB and mqttwarn then subscribe to those topics, with mqttwarn forwarding the values onto EmonCMS.

And mqttwarn is a very useful little script for monitoring MQTT topics and forwarding messages onto other services - e.g. EmonCMS (until it has native MQTT support), all sorts of other notification services like Pushover, NMA, Pushbullet, even XBMC clients!

In your case you will need to change the number 10 to 5 for an emonpi and you will need to modify the Regex to pull the second value, as well as the first one. This should read

Number Solar { mqtt="

The emonPi is based on a RaspberryPi + emonPi measurement board. The emonPi measurement board is based on an ATmega328p 8-bit microcontroller running Arduino based firmware. The following video gives a good overview of what is inside an emonPi. Note that we currently ship RaspberryPi version 3b+ which has WiFi onboard rather than the older version featured in this video.

The following system diagram shows the main hardware and software components that make up the emonPi. On the left we have the emonPi measurement board based on the ATmega328 microcontroller with inputs from the different sensors, RFM69 433 MHz transceiver, button and I2C connection to the LCD.

The emonPi uses the HopeRF RFM69CW RF module to receive data from other wireless nodes (emonTx, emonTH etc) using 433 MHz. We use the JeeLib packet format. Each RF node has a unique node ID but common network group (default 210). The ATmega328 runs a modified version of JeeLabs RFM12Demo Sketch to receive the data from radio nodes. Received radio packets are forwarded over serial and decoded on the RaspberryPi using EmonHub.

Pulse counting on the emonPi uses the hardware interrupt IRQ1 on the ATmega328. The first hardware interrupt IRQ0 is used by the RFM69CW. Only one pulse counter input is possible per emonTx/emonPi. See guide + Add Optical Pulse Sensor for more information on the optical pulse sensor.

The emonPi Raspberry Pi runs our emonSD software stack which is based on Raspbian Buster Lite. The pre-built emonSD image is available to purchase or download or it is possible to built the image yourself using our automated build script, see EmonScripts.

EmonSD includes emonHub which reads in the serial data from the emonPi measurement board and acts as a broker forwarding this data on to the local installation of emoncms via MQTT or to a remote server such as emoncms.org via HTTP.

Emoncms is our open source web application for processing, logging and visualising energy, temperature and other environmental data. It is installed as part of the emonSD software stack and provides full local data logging and visualisation capabilities.

With a few discussions going on with these devices, I figured it was worth a new thread that isn't 5+ years old. Among other people it seems, I'm looking for a cost effective way to monitor my home's energy usage, and possibly even start to automate some of my systems at home based on that usage.

So with shipping using a fright forward company like Shipito, it should be around AUD$300-$350 for a full setup. Compared to the options I listed above, this is a great price, with higher accuracy, and measuring more circuits.

Software

I'll update this as I go, but it seems most people are using (free) to monitor usage through their website and apps. I'm also interested in finding a way to integrate to Google Home so I can say "Hey Google, how much power am I using".

Engage platform with the hub and 4 CT clamp sensors has been very stable and accurate for me. Just needed to make some adjustments in PVOutput to get the actual kw output accurate. 1 short outage on Engage web servers for a few hours in the last 10 months.

Clamps are 2 x 5kw inverters , 1 on power points and lights tariff and 1 on Hot water and heating tariff. They are setup as children on PVOutput and a single graph as parent pulls all the data into a single PVOutput page.

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I'd love to hear some feed back from people that have used either.

I set myself up with the emontx V3 and purchased the wifi module that sits on the back of the unit so I didn't have to buy the emonpi receiver. (just a cost based decision) The unit hooked into my wifi easily. I purchased 3x CT clamps (as I'm on 3phase power) and a temp probe. I already had a 240ac/9ac plugpack so used that for voltage monitoring (it plugs into the emontx) and used an old phone charger usb to power the emontx unit via it's micro usb port.

I created the Emon account and made my dashboard and data started filtering through. I could monitor usage on all 3 phases and a sum of them all, ambient temperature (in my meter box) and my mains voltage data. It is much more configurable than that but I was happy with what I had.

How have you found it so far?

like I said it all worked fine once I could make heads or tails out of the data streams. I had one of the CT clamps reversed and it kept showing negative readings till I sussed it out. Once set up correctly it was a great inexpensive solution for monitoring my household consumption.

I am looking to getting an IOTaWatt. I previously had a Wattson energy monitor. While it was good it only provided details of energy consumption and generation as a whole. Having seen the 14 sensor capability of the IOTaWatt I am planning on monitoring every circuit individually. I expect that the extra granularity of circuit level monitoring will give a next level insight into my power consumption. I guess it is good to know how much power you are using but much better to also know where you are using it. I think that the IOTaWatt is an easy decision.

I have a post here about costing. Looks to me like it will be most economical to buy the unit from Open Energy Monitor and then order the CTs off Allibaba (turns out you can buy them individually for $4 USD).

Hi I bought 2 emontx V2 (through hole component type rather than surface mount) bare boards and built them using info on github. Not sure if the pcb,s are available anymore. I then use a standard Arduino Uno (with 433 shield) to recieve the info from the emontx and display it using a Nextion display. I used the other board to build a mk2_pvrouter to heat my hot water using my solar. I,ve since bought an emonbase that logs the data and sends it to pvoutput. I,m now working on displaying the pvoutput stuff on the nextion display, but the brain is a bit slower these days so may take me a while lol.

Your best bet is to size it to the breaker. You could go even further an load up the circuit and measure your max load if you know it's not going to go higher e.g. turn every light on and measure with a clamp meter, or if you're just doing your A/C, crank it to full and do the same. I think that's probably overkill though.

So my logic was with the emonPI you are clamping on the consolidated main circuit rather than individual circuits, 100A will likely be fine. Going to the IoTaWatt you'll want a series of smaller clamps, 20-50A to improve accuracy (and potentially clamp fit).

Interested to hear your thoughts on Fronius compared to the open energy monitor gear. Does it have smarts to identify your devices, and if so, does it work? This seems to be the major difference between the commercial and open sources alternatives.

They both show me consumption in real time, I know what was just switched on (pool filter, hot water, kettle, toaster, giant energy sucking plasma TV, heated towel rack etc etc) I have seen some monitoring solutions that claim to know what product was switched on but I'm pretty sure you have to let it know what the actual product was so it can remember it's consumption signature so to speak. This way the software builds a profile of your devices...

FYI the IOTaWatt has an independent USA website run by the designer of IOTaWatt. It also has a forum where the designer (overeasy) frequently helps out. Open Energy Monitor appears to be a distribution partner for OITaWatt.

The designer recommends the Echun ECS1050-L59E CT over the SCT013 available on Open Energy Monitor. Apparently he has done a lot of testing and found the ECS1050-L59E to give superior measurement as well as being smaller and having a better build quality.

Mine's still going strong. Although I did have to replace the wireless receiver on my Pi last year. It wouldn't work properly after a power outage one time. It had gone AWOL after previous outages. But re-flashing the firmware fixed it. Not the last time.

I would have started one of those threads ...

It was probably your thread that enticed me to buy my emonTx although I didn't buy the receiver and opted for the wifi module and connected to my home wifi instead. No extra receiver required.

I've done comparisons between my power bill and downloads of my readings for the same period. I was amazed that it was single digit difference.

Yeah they are right on the money. The CT clamps provided by O.E.M. are fine. Some say there is better available but to what end? when accuracy is so good as is.

What type of server are you using? I have a Linux server. Technically it has the copy of EmonCMS on it that I use. The one on my Pi just forwards to it. That way if the SD on it dies (as they have done over the years), I don't loose any data. But as my Pi is up and working, not sure if it's worth my while changing anything now.

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