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Does my meter go backwards test?


phil.g00

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56 minutes ago, phil.g00 said:

Does anyone know a quick and dirty test to establish if my Grid meter goes backwards, and if it charges me for the privilege?

If its a prepaid you can expect one of the following 2 outcomes. With the older pre paid meters, it detects the reverse flow and trip the prepaid. with the newer smart meters it assumes you have turned the meter around and charges you for the "consumption". 

The test is simple though if you have a grid tied inverter capable of feeding back into the grid.. just allow feedback and see how the meter reacts. The more complex way is to swap the supply and load wires, but that is not always possible.  

The changes of it going backwards are slim, when installing Solar, you need to order a unit that gets pre-programmed with rates ext to actually go backwards.

If it is an old spinning disc conventional Grid meter, it normally has a mechanism to prevent the meter from turning back.  Swapping wires on these are normally a lot easier. (The rest of the explanation, I cant give on a public forum.) 

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By quick and dirty you probably also mean cheap :-)

Cheapest is probably to go to the local demolition company (eg Doempie in Strand) and find an old disc-type meter. It's a bit rough, but you can check if the reading differs from the prepaid meter by about the amount that might have been fed in.

Second is something like a Carlo Gavazzi ET112. Has energy counters for both directions, so you can see how much is fed in and drawn on a day, and then you can check if the meter billed you for the sum of the two, or for the difference. There might be cheaper meters than this one too.

Third, as @Jaco de Jongh said, make it actually feed back (eg turn off all loads) for 30 minutes or so... and see if the balance on the meter goes down (which I suspect it will).

:-)

The reason some meters trip and others bill you for it... has to do with simplicity. If you simply assume that reverse power is the same as forward power, it means the meter cannot accidentally be wired in reverse (it actually happens sometimes), it really just makes the firmware much simpler (aka cheaper). In my experience the tripping variety is a newer development -- it is something specifically introduced to prevent tampering. See this video:

 

 

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3 hours ago, phil.g00 said:

What the meter does may influence the eventual system design direction.

Aaah ok! I get it, you need to test the meter BEFORE installing anything. You could get a cheap grid tie thing rom China. I mean... those things are usually rubbish and will never be approved, but if you just want to test it might be ok. Or maybe a micro-inverter, eg  enPhase.

Edit: Note, my enphase link is for a 60Hz model. 50Hz seems a bit harder to find.

Edited by plonkster
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  • 2 weeks later...
1 hour ago, Fritz said:

what will happen if i connect a  Grid-tie  inverter to my house power??

Man I wish I had one of those. For now nothing funny will happen (If it is connected correctly), but I asume you ment installing A GTI and feeding back?  The meter does have mechanism to prevent it from turning back, so if you feed back the disc should remain static. 

I still wish I had one. 

Good to see you online again Fritz, those old panels I bought from you (2 years ago?? I guess) , finally landed up on my roof , powering my secondary 12volt system. 

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8 hours ago, PaulinNorthcliff said:

They happily spin backwards.

That's why I said above, I wish I had one. Managing the feedback is the most important, as long as you dont end up with a reading less than the previous month , you will be okay. If you end up with a reading lower, the council quickly hook a test meter to your system or simply replace your meter. (With a smart meter)  

Some of the older meters does spin back without a problem, but the newer ones needs a little help to spin back. 

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On 2018/12/07 at 8:54 AM, Jaco de Jongh said:

That's why I said above, I wish I had one. Managing the feedback is the most important, as long as you dont end up with a reading less than the previous month , you will be okay. If you end up with a reading lower, the council quickly hook a test meter to your system or simply replace your meter. (With a smart meter)  

Some of the older meters does spin back without a problem, but the newer ones needs a little help to spin back. 

City Power flatly refuses to acknowledge my meter readings.

For years now they have been sending me estimated bills... which I correct... which corrections they ignore. 11 years ago I removed my electric geyser and stove/oven. City Power is happily billing me (with an escalation) as if I still had these installed. I use 16-18Kw per day. City Power bills me for 65Kw per day. I refuse to pay their inflated bill. Mexican standoff!

I'm waiting for them to summons me.

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  • 2 years later...
  • 2 weeks later...
On 2021/02/12 at 12:30 PM, Zerc said:

I don't think your meter will run backwards. There is a little symbol on the face of your meter that looks like a gear with a ratchet, I believe this means the meter will only turn forward.

meter.jpg.f729aee587634337e792481aab302457.jpg

 

ratchet.jpg.e7a710c719c73e2a63a8025678016b0a.jpg

Thanc for the reply, so what will happen if I feed a very small amount of power into it will it just stop spinning.

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  • 3 months later...

Municipality authorities won't know what is out there or what meters do what. So they'll read forums like this one to find out.

Be careful what you post, you may be very lucky, don't advertise it. Get a 500W elcheapo chinese grid-tie inverter hook it up to single pane that you lean on your fence next the meter box. Trip your feed in breaker and watch the disc.

If you are lucky keep shtum and don't tell the neighbours and switch off your inverter well before the meter reading dates.

Edited by phil.g00
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  • 1 month later...

At the risk of reviving this thread (again), I was browsing around specifically for information on this. got some clarity, thanks. I have one of those rotary meters, and when tested spins happily the other direction.

All the concerns listed above, i.e. making sure you don't go "back in time", so to speak, are there any technical considerations I need to keep in mind? Worse yet, any legal ramifications?

I am using a SynSynk inverter and generate about 3kw excess per day after the battery is charged with nowhere to go. Have the same in mind as @Sparkles to try and be a little bit more efficient with my setup.

Alternative, I suppose will be to configure it to first run off of some battery before switching to grid to reduce my consumption from there?

TIA

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  • 2 weeks later...
  • 2 years later...
On 2018/12/07 at 8:54 AM, Jaco De Jongh said:

That's why I said above, I wish I had one. Managing the feedback is the most important, as long as you dont end up with a reading less than the previous month , you will be okay. If you end up with a reading lower, the council quickly hook a test meter to your system or simply replace your meter. (With a smart meter)  

Some of the older meters does spin back without a problem, but the newer ones needs a little help to spin back. 

Hallo, please elaborate on the "Needs a little help " my meter just stops and does not reverse.

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14 hours ago, PierrevdM said:

Hallo, please elaborate on the "Needs a little help " my meter just stops and does not reverse.

As explained with picture some mechanical meters cannot reverse. 

What am I missing. 

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