PV/Home energy monitoring solution for US location

After reading some of the “Getting Started” topics, I was able to organize my thoughts and decided to start a new topic.

I just purchased a Solar PV system. I currently have production monitoring enabled. My system uses Enphase components. I just purchased the required (2x) enphase CT’s (SKU: CT-200-SPLIT, https://enphase.com/sites/default/files/downloads/support/CT-Best-Practices-EN-AU.pdf ) to enable consumption monitoring. The process to enable consumption monitoring is well documented in Enphase website. The installer (SunRun) guarantees the system for 25 years and is telling me they do not commonly get customers requesting to enable consumption monitoring, and will not allow me to do it (while they figure out how to support my request). If I do it, I will void the warranty. I also want to monitor individual circuits (air handler, HVAC unit, well water pump, dryer, etc…)

Long story short
I am contemplating the home energy monitor and solar pv monitor solutions from openenergymonitor.org. If I do that:

(1) Can these systems be integrated from the hardware/firmware and visualization software/apps standpoint?

(2), or do I need to install home energy and solar pv monitoring as two separate systems?

(3), or can I have an expanded version of the energy monitor (or solar PV monitor for that matter) and have the firmware generate data for both apps (energy monitor and solar apps)?

(4), or can the hardware and firmware be setup to support both apps and not have two separate systems running in parallel?

(5), or is there an app that integrates home energy consumption and solar production into one, while monitoring specific circuits?

Some of my early thoughts
Energy monitoring, with or without solar pv generation, is the same thing…solar power is just another circuit that can be monitored and do math with (calculate production, consumption, excess, deficit, net metered, etc…). I was already thinking about buying RaspberryPi’s or Arduinos (I have tinkered with them in the past) and attempt a solution, but a google search found you first!

Thanks in advanced!


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I assume what you mean there is if you interface directly with their system, you will void the warranty. If there is no contact nor data transfer between their system and another, and especially in the light of a recent US court ruling (regarding ink cartridges!), I cannot see that they have grounds to object. Whilst I’m not suggesting that your installer might default, similar things have happened in the past, and the user has either lost historical data, or the service that presents the current data in user-friendly format is no longer in existence.

I’m not sure what you are asking in those 5 questions. In emonCMS, you can create “dashboards” that display pretty much whatever you want to see, and on its way to those dashboards, you can do with the data pretty much all the maths that you need to. The pre-built set-ups are there for convenience - you are not restricted to just those. If you look at the “Archived” section, under the heading “Emoncms Showcase”, you might find live links to some dashboards submitted by users, and these should give you a feel for what is possible. (Unfortunately, many were screenshots that appear to have got lost in the archiving process.)

As you’re in the USA, I presume you have the normal split-phase system, so you need to look at the page about using the emonTx in N.America, and list which feeds and circuits you want to monitor. That will largely determine what hardware you need.

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It sounds as if he’s not aware both functions (consumption as well as PV-output monitoring) are available in/on the same instance of hardware and software. i.e he doesn’t need separate hardware and/or software to do both.

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Robert / Bill,

Thanks for the prompt replies. With regards to my system, the purchase and warranty agreement stipulates that, to conserve my warranty, I can’t modify or alter the PV installation​ in any way, unless approved and performed by the installer. It it’s debateable…but I not choosing to fight that battle with Sunrun at this time. That topic aside, my main intention is to get my own system (the openenergymonitor.org system) so I have full control of monitoring and data.

With regards to the questions…when I visit the shop, there are to main systems advertised. One, the home energy monitor that allows monitoring of specific circuits. The other, the solar PV monitoring that allows for global sun production and home consumption. My understanding is that each setup has its own OS or firmware managing the system, and each setup also has its own app to monitor and visualize data. My fundamental question is Do I need two setups or can I have an expanded system (emonPi + emonTx’s + sensors + etc…) that does all that. Imagine plotting solar production, home global consumption, the net power (+ or -), and the HVAC and water well pump circuits…

My current system has a third party monitoring service (thru Enphase) and that is what I was trying to get enabled thru Sunrun (the installer). If Enphase abandons the service I will be left hanging and loose my data (I think I can download it… not sure). To mitigate the risks of monitoring thru Enphase, I want to build/buy/setup my own system.

I think from your replies I can safely state that if I buy the two systems individually, I will have a solution. The question about integrating the two advertised functions, home energy consumption of specific circuits and the global solar production and home consumption, still remains.

Thanks again.


I think

you think these are significantly different. They’re not. The significant difference is the emonPi comes with one c.t., for measuring solar + grid you need two c.t’s. But these systems are packaged for the UK mains, which is single phase. Our mains supply is quite different to yours, hence my advice to read the page about using the emonTx in N.America.

I strongly advise you to read that, then come back and discuss this further with us before you order, because I sense that you might not understand the system fully yet. It’s likely that the emonPi (I think that’s what you’ve been looking at) is not the correct solution for you.

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Sounds like a plan. I will do some studying tonight.

By the way, I am in the engineering field and I am comfortable with programming languages and tech advice…so feel free to hit me with technical statements. I am far from an expert in this topic, but will do my homework as required.

Thank you for the guidance. I think we are starting to answer some of my questions.



I have an Enphase based (older Envoy) system too. (I’m in the US) As I installed it all myself, there was no installer to set up the monitoring for me. However, I was able to register and set it up myself quite easily. Here’s the link. So, if SunRun drops the ball, you should be able to set it up yourself.

Your data is downloadable, and the Enphase monitoring system will email you monthly reports if you so desire, but I think you’d be happier with an OEM system.

Here’s an example of one screen, (of several available) that you, as an Enphase system owner, will see:

The main advantage of the Enphase monitor is the obvious per-module monitoring.

Here’s an example produced by an app similar to emonCMS
(similar in the sense that it uses flot to generate the graphs, as does emonCMS)

I couldn’t justify spending ~$500 for an Enphase Envoy, so I bought OEM hardware shortly after installing my PV system in 2013. Last year I managed to find an Envoy for $240. That seemed reasonable, so I bought it.
I have to admit, it did help me find a minor issue with my system I quite likely never would have found otherwise. (Both examples are from my system.)


This is good stuff. Thanks Bill! I will check the link. The installer registered my system but I was wondering if I can change / customize the profile. I have been playing with enlighten. How do you get the power numbers to show up on top of each panel in the system map view? Cool! When you say “setup the monitor”, did you setup production and consumption monitoring via the envoy? Like shown here? I got the two enphase CT’s (I think they are Falco units) to see if I get the enphase consumption monitoring going.

Well, back to OEM…I think I got it now. Basically, I have circuits that will require only one CT to monitor power (the 120 v circuits), and circuits requiring two CT’s measurements to be added (the 240 v circuits). The baseline system I want to get will monitor the big stuff running at 240v. I can expand later. I am verifying what circuits I want to monitor to get my CT’s count. If the CT’s in the OEM website do not fit some of my lines, I am thinking about getting the same enphase units I got (I will post pics) as these will accommodate the largest lines in my panel…and go thru the calibration step to use enphase CTs. Does that make sense? I know there are options out there. The enphase CT’s were 18 USD + shipping.

I took a look at the dashboards video and the whole guide in general. It looks like I can get a few emonTX’s (one emonTx will allow for 4 120v or 2 240V circuits to be monitored, correct?) and an emonbase running emoncms and set it up via SSH. The emonPi could be used to monitor 2 120v circuits or one 240V circuit…so I can see why I need to figure out what I need/want to monitor to design the most optimal layout.

Can I have a mixed bag of 120 v (single CT) and 240 v (dual CT’s) circuits begin monitored using the OEM system? Lets say I have an emonPi + 1 emonTx. Can I monitor a 240v circuit with the emonPi, and one 240 v and two 120 v circuits with the emonTx?

Thanks again!


Only if you don’t combine the c.t’s externally. If you do combine them (as in Fig. 5b or 5c), it’s 4 circuits irrespective of whether you have one or two c.t’s per circuit. The same argument applies to the emonPi.

If you combine the twin c.t’s externally, then you can mix-and-match as you like. (If you understand c.t’s, that’s OK - but if you don’t, it’s best to run the numbers past us before you order.)

Also, if the emonTx(s) and emonPi/emonBase are reasonably close, they can share the 5 V d.c. (and the a.c. adapter if it’s an emonPi).

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Hello Robert,

Thank you for the reply.

I was going through the math and I now have a better picture of the system and its capabilities. I will do some planning over here and determine what circuits I want to monitor first, and what are the applicable parameters.

I will write down cables specifications to confirm OD’s and determine if I can use the OEM CTs or if I need to use a different unit.

Is it accurate to say that once I determine the CTs I need (qty and model) and what configuration I will use to measure power and interface the input terminals, I am ready to get the components? I will sketch a circuit to share it before we proceed.

Thanks again,



The view above is what you see as a system owner. The view at your link is what I would see if I were to look at your public page. The numbers appear on the “module” automatically. They scale according to what’s selected in the pull-down menu in the upper left corner of the screen. In my example, it’s set to Energy: today. The choices are today, past 7 days, Past month, Lifetime, and Custom date range.

By that I meant setting up Enlighten. The setup was done entirely via their website. The only number I needed (aside from basic account info) was the Envoy serial number. Once the Envoy found all of the inverters, and started sending data upstream, I was able to view it. That took about an hour, if memory serves. In fact, it was the fact the Envoy only found 39 of my 40 inverters that led to the discovery that one inverter was not connected to its module.

I don’t know what, if any, differences exist with regards to monitoring a system with an Envoy-S as opposed to the origninal Envoy (the white, capsule shaped box) as I have the older (white) Envoy.

Did you get any documentation with your CTs? I suspect they may be the voltage output type, i.e max output of 333 mV. If that’s the case, they’re not usable with an OEM system.

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Do you know what the rating of your electrical service is? Most US houses built since the 70s have 200 Amp service which utilizes AWG 4/0 Aluminum or 3/0 Copper. 3/0 Copper is an oddball size, so 4/0 Copper is typically what gets installed. Either wire has an OD of ~0.625 inches (~16mm) and is too large for the OEM shop-sold CTs. If you have 150 Amp, or 100 Amp service, your Service Entrance Wires will be smaller, and the YHDC CTs might be usable on them.

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No documentation came with the units. Tough to find documentation for these units. They are from Falco electronics. I think they are 1-5A, .333-1v.

New house, 200A.

OK, so your SEWs are going to be AWG 4/0 which means the wire window on the shop-sold CTs is too small.
You mentioned They are from Falco electronics. I think they are 1-5A, .333-1v.
With a rating of 5 Amps, you’d be limited to a measurement max of ~1200 Watts with a 240 V load and 600 Watts with a 120 V load.

If your aim is to do whole-house monitoring, you’ll need CTs with a rating between 50 and 100 Amps.
There’s a list of suitable substitutes on the EmonTX - use in N. America page.

Sorry…the CTs can measure lines of up to 200A and 600 vac (label on the CT)…the .333-1v and 1-5 amps…I am quoting info I found online on one of the suppliers selling the enphase CT. Could that be the signal output?

Just confirmed…the low V and low I values were for another CT in their site… the rating is 200A , 600vac.

The “600 V a.c.” part relates only to the insulation between the primary cable and the secondary winding. What we need to know is whether they are true current transformers (i.e. only a ferro-magnetic core with a secondary winding, that might have a voltage-limiting transient voltage suppressor or a pair of zener diodes across the output) or whether they have an internal burden resistor. If the former, we need to know the maximum voltage that you can develop across the burden resistor (effectively the VA rating of the c.t.) and if the latter, the output voltage at the rated current.

“If you combine the twin c.t’s externally, then you can mix-and-match as you like.”

When I wrote that, I was assuming that the 240 V circuits had a neutral connection (many do - for timers, control gear, indications etc) and that the current in the two legs might be different. If there’s no neutral connection to any of the loads on that circuit, or if you’re happy to neglect that difference in the currents, you only need one c.t. on that circuit.