DIY Smart Meter?

[Roger Mills]

Prompted by the Smart Meter 2 thread, it occurred to me to wonder whether there was any way in which I could monitor my electricity consumption in half-hour intervals in order to evaluate whether one of these fancy tariffs would be good or bad.

[Before I had a water meter fitted by my water company, I fitted my own meter and ran it for a year or so to see whether I would be better or worse off with a meter.]

You can buy energy monitors which either use a clamp sensor round one of the meter tails or count flashes on new-type meters. But they only appear to give instantaneous readings and daily totals.

Does anyone know of anything more granular - preferable with the ability to capture the data and insert it into a spreadsheet? Sounds maybe like a Raspberry Pi application?

If I were to have a smart meter fitted (which I've hitherto resisted!) but to stay on a fixed tariff, could this be made to provide me with the required data?

[Theo]

does it on a Pi, and will sell you the parts need to hook up to your meter for not-very-much.

Yes:

Theo

[T i m]

You could do so more frequently than that, if you wanted.

Good idea.

Some allow access to them via USB and allow you to access the (live?) data ... that you could link to an Arduino / RPi and do what you like with. ;-)

There are loads out there that, if you are into programming, could be made to do anything you want?

I would think there must be one that could? I had an early 'Owl' (I think it was) that had a serial output, but I can't remember what it gave you.

If I understand it right, if you have a meter with a flashing LED, every flash indicates a certain quantity of electricity used, say <guess> 1/10th of a kW.

If you count the pulses (clip on light detector) and integrate that over time (seconds?), you should be able to get a reasonable live energy usage?

If you want costings and have a multi rate tariff (E7 etc) then you would have to know the current time (RTC modules are easily available, or use network time if on the Net) and the cost/rate and then you can also display / log / accumulate the costs (inc adding a standing charge etc).

Something like an ESP32 might make a good platform for such a project as I think they come with WiFi and BT so good for connectivity if you need to remote the sensing from the display / logging.

Maybe we could come up with a uk-d-i-y solution between us (assuming a suitable project isn't already out there etc)? ;-)

Cheers, T i m

[Adrian]

Looks interesting, but (so far as I can see) only works for electricity metering, not gas.

Given that I don't have a power socket next to the meter, and I've already got several Pis running, would it be feasible to get the sensor head, and use the wireless to talk to an existing Pi ? (the site suggests it might be)

Adrian

[The Natural Philosopher]

= fukofalot

all you need is a current sensor and some A to D for the Pi. Then you can build yer own

[The Natural Philosopher]

could probably get just a sensor head and extend the cable to wherever you can do voltage sensing Or add a pi zero w, plus some a to d hat, and a power supply. the typical a to d is two channel, so use other channel for voltage sensing. Probably use a small mains transformer to step down mains to provide voltage sense... Pi zero W would hook into the wi-fi and be a server on the network - so write your own web app....or simply poll it for 'last 5 minutes data' etc.

[Andy Bennet]

If you have a fairly modern electricity meter with the flashing led on the front, each flash corresponds to 1Wh consumed. Just count them for each time period and job done. The meter does all the volts and current conversion and cos phi phase angle correction for you.

[Theo]

Gas is tricky - it's hard to measure without interposing something in the flow (or maybe Doppler ultrasound?). That means you're left trying to read the exist meter optically - does it give a pulse or something a sensor could be attached to? Apparently it's illegal to strap on sensors, but a non-contact way to read it might be feasible - worst case a camera pointed at the digits. It would likely need to be tailored to whatever meter you have.

They have a module which is battery-powered and does the metering, and talks by radio (433MHz I think) to a Pi.

Theo

[T i m]

<snip>

Might be a nice usage for the OpenANLP / OpenCV project? ;-)

(Should be) Easy to put a 'Does the value of the reading make sense' traps in the code to mitigate against bogus readings creating spurious data / outliers?

Cheers, T i m

[Adrian]

In message <LYq* [e-mail]>, Theo <theom+ [e-mail]> writes

The camera approach was the only one I could come up with, but I've no expertise in that area. Problem is that the gas meter is outside in a housing, so no power to run a camera from.

I spotted that, providing it works through a breeze block wall, I might be onto something.

Adrian

[Harry Bloomfield, Esq.]

Theo pretended :

Would that no involve inserting a non-metallic pipe?

[alan_m]

12 second intervals enough? I'm sure that I've seen similar from other manufacturers that provide logging to a computer or smartphone

[Harry Bloomfield, Esq.]

Theo explained on 15/11/2020 :

Short term energy usage figures can be scary, unless you are trying to track down heavy usage appliances. Daily logs, or weekly logs of usage are much more sensible. I log almost without fail, once per week and feed the data into a spread sheet of E, G and W. My sheet takes into account cost per Kw and standing charge etc. and shows a weekly charge, total charges for the week and running totals for each year, plus projected charges for the entire year. All I do is fill in the date and the three numbers each week.

[Clive Page]

My non-smart electricity meter - not sure of the age but at least 15 years - has a small red LED which flashes at intervals, faster when the power consumption is greater. I have only roughly checked it against the dials, but I think there are N flashes to the kWh for some N that I can't remember. A simple photocell monitoring this LED ought to work, and I've thought of rigging up something but not quite got around to it. Counting flashes per minute would get a pretty up-to-date consumption figure.

Our gas meter doesn't have the same thing of course, no ready supply of electricity to power it, but it does make a faint but obvious click once per rotation of some internal wheel. I assume that I could similarly monitor gas usage with a microphone and counter.

[Brian Gaff (Sofa]

Which brings up the whole idea, how does a gas meter work? I have no gas, but am intrigued as many people with smart meters are told to change a battery in the gas bit. One assumes then that it the gas is coming in at a different place to the electricity, and there is no mains connection it talks to the other mete using battery power, sounds a bit crude. Brian

[Harry Bloomfield, Esq.]

Brian Gaff (Sofa) formulated on Monday :

The battery is not customer swappable. The battery is a long life one

I have no idea how the modern mechanism to record the flow works.

[Martin Brown]

Yes but it is probably easier to buy one of the Owl type devices or move to a tariff where your supplier will give you one as a part of the deal.

Is probably good enough for most purposes particularly if you also log exertnal temperature along with your daily consumption. And make a note of when you are running the glass furnace or other power hungry devices.

I think domestic users get a transponder to use with a PC. I have no mobile signal so smart meters are not for me.

[Andy Burns]

smart gas meters have a D-Cell Lithium Thionyl Chloride cell, 15 year shelf life, 3.6 volt, 19 amp hour, that's why gas meter sends readings to in-home display much less frequently than elec meter

[Andy Burns]

Yes, I understood the supplier was responsible for changing the battery, not the customer.

This type

Mine uses ultrasonic time-of-flight measurement

[Spike]

Scroll down and download the PDF.

Data recorded every five minutes, stored for 28 days