Hi, I have been trying to read through OpenEnergyMonitor documentation, and it seems very comprehensive, but it is not easy to follow for a non-electrician. I mean the sort of documentation which doesn’t assume the reader even knows what a CT clamp is. I would like to suggest that the OpenEnergyMonitor documentation contain an intro page with headings something like this:
You want to monitor your overall energy usage? Here are the options:
[discuss monitoring the led on your smart meter if you have one, accessing data from smart meter provider in different countries, vs putting a CT clamp on your mains wires, vs any other options?]
You want to monitor energy use of plug-in appliances? Here are the options:
[discuss smart plugs and how they might link in with open energy monitor (do they?)]
You want to monitor energy use of hardwired appliances (for example cookers or other appliances which are wired directly rather than plugged in).
Here are the options: [discuss CT clamp options]
You want to monitor your heat pump? Here are the options:
Different data elements you might want to monitor: energy consumed by the heat pump itself, other ancillary equipment, temperature of water in tank, temperature of water flowing in and out, temperature of air. How the data you might collect from installing openenergymonitor equipment might differ from what the heat pump manufacturer app might give you, or how the data might be more accessible or granular.
You want to monitor your solar PV panels? Here are your options:
[Is this also CT clamps? How this might compare to the data from your solar system app, data might be more accessible, granular etc]
CTs - what they are and how to install
Do you need an electrician? How much electrical knowledge do you need to install CT clamps? Which CT clamps do you need for what purposes?
Collecting your data
[Discuss how to collect the data from any CT clamps and smart plugs you have into one place and analyse it.]
Now you have decided what you want to do, what you need to buy in order to do it (shopping list)
I couldn’t write this documentation at this stage as I don’t know enough. If I do end up knowing more in future I would like to help write such documentation. I am currently not sure what I need to buy to implement the above, and whether I need an electrician or not. Are there people here who could fill in this material? Then possibly it could be put up as an intro page for non-electricians ? Something which starts from a person who is interested in understanding their energy usage but doesn’t know much beyond that.
If there are resources already there I am missing which contain this material which don’t assume a lot of prior knowledge, please point me to it.
I appreciate what you’re saying, and as someone who had written some of the documentation you refer to (and having been in the electrical/electronics profession for 50+ years) the major problem as I see it, and which you’ve more or less hinted at, is the difficulty of finding what you need here. I’m totally convinced it is all here, but a lot of the time even I can’t find something I know exists.
Of course, a lot - and I mean A LOT - of very useful information, much of it at the level you’re aiming at, has appeared in the forums (I’m including the archived forum) and promptly got buried, because that’s where absolute beginners like yourself have asked the basic questions and started up the learning curve, just as you are doing now.
I’m happy to pick up some of your headings, we’ll need others to pick up the stuff I don’t know too much about.
And a plea: Please don’t call split core or any other current transformer a “clamp”. They aren’t, I believe it’s a Chinese mis-translation. There is a portable instrument called a “clamp ammeter” - this is the only meaningful use of the term. The other two sorts of current transformer are the split-core (which you slip over a wire and clip or bolt the two halves together) and ring-core (or sometimes called solid-core) which needs the wire to be disconnected to feed it though the aperture.
Thanks for the correction on the wording and explanation about split core and and ring core!
That would be great if you can help write or point to the sort of material I am looking for above, and perhaps we could then submit it to the documentation introductory pages via github when we are sure it’s right, so other people who might be in the same beginner situation might benefit from it.
No, apart from me not understanding Github (and having been put off by not being able to find any ‘official’ documentation and then getting totally misled by badly written third party rubbish), and because I won’t live long enough to learn it, I have the absolute minimum to do with it and so won’t entertain the idea of going down that route. I’m afraid if this is your method of working, I won’t be able to help after all.
I’m interested in contributing to this, specifically the last bullet point from the original post here. I’m monitoring 18 circuits (using CTs) in North America and can add info about that type setup. I’d also be interested in knowing how to monitor heat pumps and PV. I couldn’t figure that out when I was buying gear so I gave up and reduced my scope to just measuring electricity usage.
This has some additional challenges such as:
The shop doesn’t sell an emonVs for split phase (the 3-phase option should work, but it’s confusing when you’re trying to pick out parts)
You don’t need one power supply per device, but you do need a splitter
And then after you have the hardware:
The devices may not ship with the correct firmware (mine didn’t)
Explaining the difference between measuring energy and power
The setup process, especially with the software (after hours of reading documentation and tinkering, I still haven’t managed to figure out how to set that up to measure power and energy)
As you may have guessed by this point, I’m writing the documentation that I need so I can remember what’s going on when I have to set up my own system someday (e.g. the SD card gets corrupt/dies). I’d much rather keep these notes in the official repo so others can benefit from them, and so I don’t lose them.
My plan is to keep searching the forums for answers, experimenting, creating/improving documentation and submitting pull requests. I’m not sure where a “buying guide” should go. The docs seems largely focused around information about each device, which is great after you know what device you want, but it’s tricky if you want to quickly determine if any of these devices are right for you.
Having written the software library both depend on, I assure you the emonTx4 and emonPi will work on the North American split-phase system. The limitation is this:
It only needs the sketch in the emonTx or in the emonTx board in the emonPi customising according to the documentation I produced to support the software, and I don’t know the reason why this isn’t available - maybe a lack of standardisation across the continent means too many variants would be needed?
Have you tried asking on this forum?
Only this weekend, I sent some words to @ElaineCB. Here’s the bit about power and energy.
[A topic that is needed], because a lot of people who should know better get it wrong: What is power, and what is energy?
Energy is what you pay for. It is measured in watt-hours (Wh) or kilowatt-hours (that is watts times hours). In practical terms, an electric heater with a power of 1 kW will use 2 kWh of energy over the course of two hours. It’s the count of the number of flashes of the LED on your meter.
Power is the rate at which you use energy. It’s the speed at which the rotating disc in the old Ferraris meters spun round, or the rate at which the LED on your meter flashes. If your meter changes by 2 kWh, you could have had your 1 kW electric heater on for 2 hours, or charged your electric car at 3 kW for 40 minutes.
Some serious questions for you, inspired by a PM from my colleague in the USA: Would a glossary of terms help you? Would a more detailed index to the Docs section (in addition to the contents list) help you? Not that it’s ever likely to happen for very obvious practical reasons: would an index to the forum help you?
The split phase firmware is available and can be installed just fine from the Admin → Update screen. It’s just that people might not know that they need to do this, and that’s what I intend to add to the documentation.
Yes, I asked in this thread and you confirmed that was “one that got away” from being included in the documentation. So I know what needs to be added to the docs and it’s just a matter of doing so and submitting a pull request.
Yes. The FAQ suggest http://www.electropedia.org/ for looking up terms, but their definition for energy says “Specific energy, or energy per mass, is denoted e or w.” which makes it sound like energy is measured in Watts. I posted about that here and I now know that energy is not measured in Watts, but rather Wh (or KWh, MWh, etc.). Electricians wouldn’t have made that mistake, but then again electricians wouldn’t have to look up the definition of energy either. Having a glossary would help avoid people (specifically, non-electricians) being confused by what electropedia says.
Maybe. I’m going to re-read the section on setting up emonCMS and try to better understand how everything fits together. It didn’t work for me the first time through, but now that I know more about how the system works (e.g. measuring voltage instead of assuming it is 120V; that power and energy aren’t being used interchangeably, etc.) it might all make a lot more sense. And that section is already linked to from the emonPi2 setup instructions, so I think we’re pretty good on linking there.
Probably not. During the initial setup, I want to find the information I need quickly. Reading through a long forum post to get the context is not well suited for that. The forum posts very helpful when I run into a specific problem and a forum search pulls up someone who has encountered the exact same error, but that’s not the type of information or level of detail I want when I just want to get a basic setup working.
I’ve just sent some words on this to @ElaineCB. It’s an expanded, but not very much, version of the few sentences I’ve often written in the forum for others who’ve had difficulty grasping what emonCMS is. And I’ve referenced this Emoncms Core Concepts — OpenEnergyMonitor 0.0.1 documentation but note it’s not entirely accurate and needs updating.