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In order to save energy and to investigate the benefits of a balcony solar array (300W), I am trying to find out my total electricity consumption with low latency and high temporal resolution. Currently, I know my electricity consumption on a yearly basis with a latency of about 4 months. Meaning, we will find out my total 2022 electricity consumption in April 2023. I'm in Germany. Apparently, in Germany, the grid operator is obliged to provide an interface on its metering device to enable the customer to access the meter reading, so it should be possible to find this out more frequently.

We have wall socket meters, but they only help for devices that are powered via a wall socket. For devices that directly connect to fixtures, they don't help. I have no clue how much is used by oven, stove, or bathroom fan.

When we lived in England, our electricity provider provided us with a smart meter, and we could tell electricity consumption with a resolution of about 10 seconds in near real time. However, for a smart meter, we might have to wait until 2032.

Does there exist a plug-and-play device that I can simply connect to my meter, without electrical DIY skills?

I found a device that plugs into a classical electricity meter, but it's out of stock. I found someone who built their own solution but I don't really have the skills or interest to build my own.

One complication may be that our meter is in the basement, from where there is no reliable connection to my home WiFi.

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    Flukso is an open source power meter, I'm not sure of your regulations but installation involves putting clamp sensors on the relevant wires in your distribution board. That's something that could be cheap to get an electrician to do. I suspect that there aren't any general-purpose, non-invasive, non-technical solutions. All the ones I know of are either "point a camera at the meter" then write a bunch of code, or start with "open up your distribution board"
    – Móż
    Commented Jan 10, 2023 at 9:48

2 Answers 2

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I'm currently installing the power monitoring for my solar panels so here we go...

If the utility meter is in the basement and your wifi doesn't reach there, then to talk to the meter you'll have to pull a wire to the basement. This is likely to be a lot more annoying than installing a smartmeter in the house's electrical panel, which should be located inside the living space.

In addition, these old meters only provide a pulse output, which sends a blip every time your house consumes a set amount of energy. So, to know how much power you're using, you need a device that measures the time between pulses, and the measurement will only be updated on every pulse. So it can be quite slow to update, and it is very inconvenient for what you intend to do.

I would recommend you measure power at the house breaker panel. This requires an energy meter, which needs to measure both voltage and current. The least invasive ones require:

  1. Two AC mains wires for the meter's power supply, to connect to a circuit breaker or to an electrical socket if there is one nearby. This also allows the meter to measure voltage.

  2. A current clamp, which looks like this, to put around the main wire coming from the utility meter, which measures current drawn by the whole house.

Note a current clamp measures the total current going through the hole in the middle, and it cares about polarity, that is the direction current is flowing as it goes through the hole. So if you run the whole cable through it, since the cable has one wire carrying current in one direction and another wire carrying current in the other direction, the clamp will measure the sum of both, which is zero. So it won't work. I'm mentioning this in case you thought you could avoid opening the electrical panel ;)

If you have three phase power then it needs to be three phase, it's just 4 wires and 3 or 4 clamps instead of 2 wires and 1 clamp.

Anyway, how to choose a smartmeter. Welcome to the wonderful world of home automation, where absolutely nothing works like you want it to out of the box.

Option 1)

If you know Python, the simplest is a modbus smartmeter. It speaks modbus, which is a protocol of about Neanderthal tech level. Any tiny computer like a Pi can talk to it with a cheap USB-RS485 adapter, and then you have to figure out what to do with it, make some plots, put the data in a database, whatever, you're in charge. All these meters update about every second, so it's pretty fast and real-time.

Option 2)

If you want a device that does "something" out of the box without getting your hands dirty, then I'd recommend a wifi smartmeter. Installation is the same, some will mount on the DIN rail inside your electrical panel which is the best if there's enough space to put it in, some will mount on the wall so you get an extra ugly box hanging plus a bunch of wires running to your panel for decoration.

In both cases, count about 15 minutes to install it for someone who knows what he's doing, unless there is a surprise inside the electrical panel. If you don't know how, have an electrician do it, or a friend who's handy with this sort of thing. It's really not difficult for someone familiar with the stuff.

HOWEVER

This is the wonderful world of home automation, where absolutely nothing works like you want it to out of the box. Which means, most likely, the wifi smartmeter will upload your data to some Chinese cloud servers and only let you access it with a barely (un)usable garbage app, like the ubiquitous tuya wifi "smart" sockets. In addition, usually most of the useful options are on a subscription basis, and the cloud nature of the thing means it updates a little slower than if you could access it directly. This is a hard fail IMO, I absolutely hate these cloud apps from which it is cumbersome or impossible to pull data with a script in order to integrate with other systems. Also you have to give your wifi password to the PCC.

Option 3)

If you want a device that does what you want out of the box, then you'll have to make really sure it does so before ordering. The best way is to ask someone who has one already.

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There are current clamp meters. You just put a sensor around one of the wires. It has to go around live or neutral, but definitely not both. They make assumptions about the voltage (but this does not change by much), and phase (also should not change if you have only resistive loads).

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