3 Phase whole house, PV and heat pump monitoring required


I posted about this topic a few months back but now we are in the house I am revisiting the topic and keen to get something sorted for energy monitoring.

Our site is fed by 3 phase into our garage. From here it feeds our 3 phase PV system (10.8kw), two of the phase go to consumer units in the house and the other phase is used to power the garage. I would like to monitor PV generation, export and consumption. Also, measure consumption on the 3 consumer units from each phase. From what I have read, I would need 3 x EmonTx with 3 x 100A clip on current sensors for the consumer units but would I also need another 3 for the PV monitoring or could it all be done from the 3 x EmonTx’s? The house and garage are detached and approx. 5 meters apart but the consumer units are at opposite ends of the property so maybe 20 meters total. The house supply is running through a Polyphase Energy Meter 5219 which I believe has an optica/pulse output which could also be used but I am not sure if this is better/what it would replace from the EmonTx + clip on sensor?

Also, I have an ASHP which I would like to monitor. This is run from one of the 3 phase and is in the house so would need to be monitored seperately from the 3 phase supply and PV system. I have spoken to Trystan previously about the through-hole kit for this but I cannot see it on the website and he must be busy as he hasn’t replied to my email re. purchasing the kit. Could anyone steer me in the right direction for this? I believe I would also need a single phase electricity meter on the heat pump supply (although I have a supply to an indoor unit and an outdoor unit seperately for my heat pump so I might need two…??), such as an Elster - A100C, and a heat meter, such as kamstrup 402 with the MBUS module, to be able to monitor this correctly. Although could I just use an EmonTx with two clip on current sensors to measure each supply to the heat pump without the electricity meter being required?

Any advice greatly appreciated!



The easy one first: The meter pulses will only give you consumption, you will get no pulses when you are exporting. So although by definition that meter is totally accurate, the pulse output is only half the story. The other point, which might not bother you, is you only know about consumption after the event when a pulse is generated. And of course, resolution is one pulse (1 Wh for your L+G meter).

If you had the 3 emonTx’s in the garage, where presumably you have your meter, Henley Blocks and the PV isolator, you could monitor both PV generation on each phase and the nett import/export on each phase. (The difference of course being consumption on each phase.)

But that won’t give you any details about individual circuits.

It looks as if this will need its own emonTx (Can you confirm it has a single phase supply?) or, from what I know about it, this:

Is this the heatpump monitor that’s presently in development?

Yes, the emonTx/Heatpump Monitor would surely be instead of, not as well as, another meter? The comment above about pulses applies here too.

If the indoor and outdoor units are on the same phase, and fed from roughly the same place, then a CT on each will give you the individual consumptions of the two units.

Many thanks for the reply.

So I have ordered 2 x EmonTx with a 100A clip on sensor for each and 1 x EmonPi which already has 1 x 100A clip on sensor with it. So that should give me web access and the ability to monitor each of the 3 phases. I am not sure that I would need to monitor individual circuits as I presume I would see energy fluctuations by turning appliances etc. on and off and seeing what effect this has on overall consumption?

Re. the heat pump I wanted to monitor heat pump performance, hence the heat meter rather than just power consumption as I would be able to get this from the 3 phase monitoring anyway. The heat pump will probably be secondary once I get my head around connecting up the EmonPi, Tx etc.

I presume I would need to configure the data output using Emon CMS to display what I need? To be honest this wouldn’t need to be much more than each of the 3 phases import, export and generation plus an overall total for the 3 phase.


Indeed you would, but some people like to tie the consumption to individual circuits or even appliances (though that’s hard with the UK’s final ring sub-circuit of course!)

Yes you would. Probably the best way is to play with it and see what does what. The user guide might help you to get started.

You have ordered the ac adapters for the emonTx’s as well as for the Pi? You need those if you want real power and to distinguish import and export on the grid connection.

Hi Robert,

Thanks for that, ok so I am on the right track then. Thats good news!

I ordered 2 x AC-AC adaptors for the Tx’s but a 5V DC adapter for the Pi…do I need another AC-AC for the Pi then?

I must admit I was a little confused with all the different options but I wanted to take advantage of the discount being offered so rushed the order!

You do indeed, if you want to be able to measure real power. It isn’t supplying power to the Pi, it is only giving it a measurement of the mains voltage, which you need to determine the direction of power flow.

(The emonTx can run off either the ac adapter (but only if there are no add-ons) or the DC 5 V USB supply. That arrangement is not possible with the Pi because it needs a lot more power.)


So I now have the equipment and finally getting round to installing it!

I have the following;

1 x EmonPi
2 x EmonTx
3 x 100A clip on sensors
1 x 5V USB power supply (EmonPi)
3 x AC-AC power adaptors

My question is do I have enough kit to measure both 3 phase usage and 3 phase PV generation/import/export etc? Is it as simple as putting the clips on the 3 phase just before the utility meter or do I need to put them between the PV inverter and the generation meter? Also, it sounds as though I need to put the AC-AC adaptor on each phase to match the current clip. Is this the case? For example, 100A current clip on L1 to EmonPi + AC-AC adaptor in socket running on phase L1, same for L2 and L3? This would be difficult as the 2 phases go from the garage to the house and I have no sockets on these phases in the garage. A way round this could be to put 2 x EmonTx in the house at the two consumer units and leave the EmonPi in the garage on the other phase but this may leave me short to measure PV as the PV inverter is also in the garage.

Hopefully attached is a schematic of the current set up but not sure how to upload images!


Red Bluff schematic_181016.pdf (30.5 KB)

You succeeded - but of course by now you knew that. :grin:

It might be a ‘no’ to that - how were you intending to know what your PV generation is? If you can get that from your inverter or generation meter, then yes, you have enough c.t’s; but if you must measure the current, then you need another 3 c.t’s.

There are basically two ways to measure 3-phase: The obvious way is one emonTx per phase (I’m counting the emon bit of emonPi as an emonTx for that). That is potentially the most accurate. The other is to use one emonTx to measure 3 currents on 3 phases, plus the voltage of one phase, and assume the other two voltages are the same, using the 3-phase sketch.

To give you the most information, albeit with some inaccuracies, what I’d do, now that I can see exactly what your set-up is, is:

One emonTx on the garage 3-phase upstream of the consumer unit (on the meter tails). This will give you nett grid power.
One emonTx on the 3-phase inverter output. This will give you nett inverter output (or a small consumption at night!)
Your emonPi in the house, with 2 inputs that you could use for dedicated circuits on the same phase.
Then phases 1+2 grid + phases 1+2 PV give you house consumption, phase 3 grid + phase 3 PV gives you garage consumption, phases 1+2+3 grid give you nett import/export, and phases 1+2+3 PV give you nett generation.

If you do that, you need 3 more c.t’s, possibly yet another 2 for the emonPi.

The most accurate way would, as you say, need the provision of 2 more sockets in the garage to monitor the other two voltages. You’d still need 3 more c.t’s.

But you don’t need the c.t’s if you can get generation data from your inverter or your PV meter, either on a data bus - maybe Ethernet or Bluetooth, or maybe an optical pulse counter on the meter.
(A pulse counter on the grid (tariff) meter doesn’t give your export energy, so that’s not helpful.)

If you power the two emonTx’s on two phases and give the emonPi a voltage input on the third, you will know the three phase voltages, but it won’t help the power calculations in the three-phase sketch (because the emonTx can’t receive that voltage synchronously to be able to use it). But you could use the voltages to apply a correction in the maths of emoncms.

You could load a 2-phase sketch (derived from the 3-phase one) into your emonPi if you wanted to check 2 powers on 2 different phases in the house.

I have finally got around to fitting the kit and must confess I am a little lost…

I purchase another 3 x c.t’s and have a socket on each phase in the garage. The phase the emonPi is on, has a double socket to for USB power and voltage. I have a c.t on L1, L2 and L3 just before the utility meter and a c.t on L1, L2 and L3 between the inverter and the generation meter, L1 Usage to ct1 and L1 Generation to ct2 on each emon etc.

At first I could only see one emonTx but found the notes about dip switch settings, changed that and now I can see the emonPi and 2 x emonTx. One of the emonTx is showing a vrms of 5V, the others all show around 240V. Both Tx’s show temps of 300 (dont have any connected), rssi of approx. -30 but not sure if this is normal. I haven’t done anything regarding a ‘3 phase sketch’ which I think I need to do? I am seeing some very strange spikes of a few kW’s when nothing is on etc. so I am guessing something is not right…??

Firstly, you must have the c.t’s plugged in before the a.c. adapter plugged in. I guess you’ve done that, but a quick warning - c.t’s that aren’t plugged in, and temperature sensors, and a.c. adapters if you run off 5 V or batteries, are ignored until you reset (emonTx) or power up again (emonPi and emonTx). I mention this because it catches people out.

OK, that 5 V is wrong for a start. That needs chasing down. The adapter should give you about 11.6 V (at 240 V).

That’s correct.

It is actually quite good.

Yes, you will need to download that, and upload it into the two emonTx’s. Be sure to choose all the setup options correctly (it’s the same sketch for everything) and follow exactly the calibration instructions in the sketch to align the second and third phases correctly. Also note the sketch ignores the DIP switches - you set the NodeID in the sketch. So you need 2 customised copies, one for each emonTx.

That, I suspect, is noise pickup from somewhere. Was it when a fridge or freezer turned on or off, or something like that? Maybe even a neighbour’s?

Hi Robert,

Thanks for the response. Neither Tx’s give 11.6V, one shows 5 vrms and the other 251 vrms.

All of the equipment is in the garage with no devices switched on, it is separate from the house. I should probably get the 3 phase calibration sorted first and then see what problems I am left with.

Could you point me in the right direction for the 3 phase sketch? I have found the 3-Phase Power on openenergymonitor.org. I have also found ‘emonTx V3 3-phase Firmware’ and the emonUpload tool but to be honest, for a mechanical engineer, it’s a completely foreign language! There is so much information floating around it is difficult to see which is the correct path. Also, I dont have a USB to UART programmer - do I need one to be able to do this?

Also, am I right in thinking the emonTx’s wil be powered from the AC-AC power supplies so I can remove the batteries from each of these?


Yes, you’ll need one of those…
Although… you should be able to hook it up to a Raspberry Pi (or the Pi within your EmonPi if you unplug the “emon” part from the Pi’s GPIO header) via the TTL serial pins on the Pi’s GPIO header.

Which probably means what I typed above was of little help :slight_smile:

The 3-phase sketch is on github here
I used the Arduino IDE to compile and upload it, if you do that, copy the files in the “src” folder from that GitHub link into your Arduino’s “Sketch” folder so its easy to find it in the IDE.
Other upload mechanisms are also linked to on that GitHub page
All of the instructions for calibration are in the comments at the top of emonTxV3_4_3Phase_Voltage.ino.

Correct., but check JP2 as per this part of the EmonTx 3.4 Wiki page:

I was talking about the voltage you measure with a multimeter on the co-axial plug on the twin flex coming out of the a.c. adapter.

The official way to load the sketch involves installing Platformio. For me, that was a nasty piece of software that screwed up my system. I prefer to use the Arduino IDE, and get and install the supporting libraries that are needed, manually. I can supply the instructions for that if your prefer. I personally can’t help you with the ‘official’ method because it didn’t work for me.

You are right. This could also explain the 5 V reading - I guess your a.c. adapter for that one wasn’t switched on, or is faulty.

<sniggers>. My dad was an MIProdE, so even though I’m an MIEE, I learned a bit of your language :sunglasses:

FWIW, I had the same experience. Maybe it was just because I was already familiar with the Arduino IDE though.

No, it moved my file system around - without even telling me, let alone asking. I know that for absolute certainty because my script for updating from Github didn’t work. It cost me an hour or two to find where it had moved whole directories and to put them back. That’s malware in my book.
I’ve used a few IDE’s in my time, but never encountered behaviour like that before. I’m glad it wasn’t just me.

I wrote/updated the Win 8 / WIn 10 guide, and mercifully I’ve still got the instructions, which have been deleted from this site, as a couple of .pdf files. Let me know your OS version (MacOS, Linux or Win 10).

Thanks Gents, hopefully I will be above to follow the instructions!

I have ordered the USB to UART which should arrive this week then I will have a play. If you could give me some pointers for using Arduino IDE that would be great!

Thanks again,

The Windoze, Mac or Linux version?

Windows please :slight_smile:

Here they are:

Installing IDE W10.pdf (249.8 KB)
Installing Libraries W10.pdf (125.4 KB)

[“Installing IDE…” corrected in line with renaming of “Ports” menu item.]

Brilliant, thanks Robert.

The USB to UART has just arrived and is sat on my desk so will no doubt be messaging later when I get completely lost!