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Solar PV made my electricity meter run backwards

Posted by Gabby Mallett on 3 February 2017 at 1:50 pm

They found me, I don’t know how, but they found me. 

Yes, I know, it’s a quote from Back to the Future and of course I do know how they found me. My energy supplier finally worked out that my meter was running backwards because I have a PV system. 

I had a 3.01kWp system installed back in September 2010, just a few months after they were introduced (and yes I did get the maximum rate of 43.3p which is increasing with its index-linking). Like many other people at the time, I didn’t bother looking around for a different energy supplier to provide my Feed in Tariff (FiT), I just went to my current electricity supplier. It seemed to make sense to have one organisation doing both. I assumed they knew what electricity meter I had and I really thought no more about it.

With the electricity tariff that I was on I was supposed to send monthly meter readings. Well, I forgot much of the time even though they sent me an email reminder, but the times I bothered to take the reading they had often already sent me a bill, so I didn’t bother submitting.

Then an interesting thing happened. I tried to put in a meter reading and I got a system message which said ‘oops, that isn’t the reading we were expecting’. Of course my first response was to write a snotty letter to say that ‘no wonder it’s not the reading you were expecting as you always over estimate my usage and I am horrendously in credit, and you do it with my gas too’.  Suffice to say it was a pretty strong message. They responded very nicely to say the reason for the message was that the meter reading that I had submitted, in October, was actually less than the reading I had submitted in May!

So, they had finally twigged that my meter was actually running backwards whenever my PV was producing and I wasn’t using. This meant that during the summer I would be producing 10-15kWhs a day which would move the numbers back and I would get home and then use less than this in the evening. My supplier then wrote to me and said that I needed a new meter. They said that they felt my meter was faulty and I may be paying more or less than I needed (clearly less in this case) and very nicely they said that they wouldn’t be trying to reclaim any underpayment from me. 

So then we had to arrange installation of a new meter.

Also see:
How easy is it to get a new electricity meter installed?


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9 comments - read them below or add one


PigletComment left on: 26 March 2018 at 12:58 pm

We've just had a PV system and SunAmp battery installed. Our grid meter runs backwards slowly sometimes and the reading shows  that we have used 120 Kw of grid electricity , which seems to be the same amount our PV meter shows we have generated.  In a dilemma whether to tell our electricity supplier about the meter - we don't want a smart meter.

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Bridport John

Bridport JohnComment left on: 18 September 2017 at 11:09 pm

I have a 4kW PV array, fitted in 2011.

Just had a new electricity meter fitted, replacing one that was installed in 1984! It's an EDMI Atlas Mk7B. I can confirm it seems to have a register for export to grid. The manufacturer's data sheet and manuals confirm it has this capability but the exact display is configured by the supplier. After four button puches the registers I get are R1 (daytime) R2 (off-peak) TOTAL (=R1+R2 with a rounding error half the time) APP E which seems to be the total export in KVA. The rest of the registers I see are about peak demand, phase lag etc.
These meters have been around since 2010 and EDMI applied for UK type approval in 2012. Why it's taken so long to get them installed amazes me.

So far I seem to be exporting about 50% of what I generate. But the only thing running at night is a small frig and PIR operated security lights.

As to expense, these smart meters are on sale on ebay at £30 incl postage. That's no more than a non-smart basic single register pulse meter. No sure how you'd program your own though!

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GaryComment left on: 13 February 2017 at 3:59 pm

From that persepctive i agree that people will in essence be forced to get into a more accurate place but what an expense to achieve that.  What I am not convinced about is whether that will make more people prepared to switch.  Actualy, call me old-fashioned but why do we allow energy providers to have more than one price/product - it's like allowing the water companies to offer 4 water tariffs or petrol stations to offer the same fuel at 4 different prices - and why do we expect there to be significant differneces between the endergy providers in the first place?  They aren't really driven by competition as there isnt really a competitive market.  But hey ho, that's what we have and what we all have to dabble with.

Getting back on topic, I still think it wold be useful if you guys could do an in-depth artical on smart meters and PV/wind etc - how they work, what they do/dont do and so on as it really is difficult to track down quite what the real position is.

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NEF Gabby

NEF GabbyComment left on: 10 February 2017 at 9:00 am


I do get what you are saying, and to a degree totally agree with you.

However, you would be surpirsed how many people genuinely don't know how much energy they are using. They pay by direct debit and are in some amount of credit or debit and have had estimated bills for a while. They rely on a meter reading every two years to sort out their billing.  Many of these people don't dare switch supplier as they are too worried that they will have a hefty bill to pay to their current supplier before they go. Smart meters will do away with this as people will know exactly how much they are using and how much in credit or debit they are at all times. It means that people who do want to switch will have proper readings to use on the switching websites to get accurate ideas of how much they could save and won't have to struggle with Tariff Comparrison Rates etc.

I don't think they are that smart, but I do think they will make a difference to quite a lot of people.


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GaryComment left on: 8 February 2017 at 7:07 pm

Not being critical on any contributions here and not to put too fine a point on they are not smart at all.  I have an immerSUN which with a single sensor is able to detect current flow direction (import v export) and with a second sensor can give me generation too.  I now have the complete set of import, export, generated, diverted to immersion heater or whatever and total house use. 

PV has been with us for far longer than the concept of smart meters and certainly before they settled on any sort of industry standard, so why, oh why, has such simple functionality not been incorporated - the ability or otherwise to drink excessively in a brewery comes to mind!

Personally i cannot see any benefits at all from smart meters, other than perhaps that being able to see how much you are using does concentrate the mind and ask you to qustion why you are importing so much.  But that said, i think you need be a bit geeky to do even that and i am sure that many smart meter monitors will languish in the back of cupboards once the novalty wears off.

And as for doing away with "wrong" or unexpected bills, what rubbish.  Most people must surely be on direct debit these days, and know that the quarterly bill is just for info and that it peaks in winter and troughs in summer.

So, what benefit does the customer get for the billions they are spending on having these meters imposed on them?

Rant over...

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NEF Gabby

NEF GabbyComment left on: 8 February 2017 at 8:48 am

I think I have got to the bottom of this now.  I did say in a previous blog that smart meters 'weren't compatible' with PV.  Actually some of them are 'compatible', meaning that you can have a smart meter and a PV system.  What they currently aren't able to do is to seperate the incoming current (that we are using) from the outgoing current (that we are generating).

Basically they work in a very similar way to my energy monitor.  They just measure the current, but not the direction of travel. So I can go home and look at my monitor when I am using virtually no electricity (just radio alarm clock, clock on micrwave and fridge freezer) and it will show quite a high use, but this is not 'use' it is generation from my PV.

Then it depends on what smart meter you have and whether you have an export meter for your PV.

The long and short of it is that for the moment you won't get a smart meter that can tell how much you are using and generating.



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GaryComment left on: 7 February 2017 at 9:31 pm

I didn't think smart meters work properly with PV.  Not sure what "not work" means but would be keen to know.  Are you now showing accurate readings and what does it show you re PV generation/export etc?

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ChasComment left on: 4 February 2017 at 2:44 pm

Yup. Same thing just happened to me with my Supplier, after 2 years with meter running in reverse at times

I was also surprised that they did not fit a smart meter.

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pechisComment left on: 3 February 2017 at 11:13 pm

Same happened to me, I agreed to a new meter assuming it would be a Smart meter.

When I checked with Eon, it would have been a new meter but not a Smart one, crazy as they would have had to return within a few years and change it.

Anyway I have a Smart meter now, novelty has worn off so waste of money from my point of view. However probably means I'm ripe for variable tarriffs when they are introduced!

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