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Import and export meters and the feed-in tariff

Posted by Cathy Debenham on 29 March 2011 at 9:59 am

I've been a bit confused about export meters for the feed-in tariff. When my solar PV panels were installed my installer put in two meters. One measures the total amount of electricity generated. The other measures the amount I export.

The meters are identical. So identical that they even have consecutive serial numbers. So the reason I'm confused is that the feed-in tariff is paid based on my total generation meter reading. Yet, my electricity company can't pay me for exported electricity based on the export reading. This seems odd because the export reading is smaller, and the tariff so much lower, than the total generation reading.

Now I know why. It's not the electricity companies that make the rules, but DECC (regulated by Ofgem). And the rules say that if you're going to send electricity into the grid you need to have a meter with an MPAN number (you already have an MPAN number on your import meter).

Getting an official export meter with an MPAN number costs about £70 a year. This means it isn't cost effective for most domestic installations, as the exported electricity (at 3p a kWh) won't be worth enough to cover the cost. So instead the export figure is 'deemed' to be half of your total generation.

In my case, this is an under estimate. I have a 2.1kWp system, which has generated 1,966.8 kWhs of electricity. Of that, 1,266.7 kWhs has been exported - which is more than half. And I work from home. So people who are out all day will probably be exporting an even greater proportion.

I'm not the only person a bit confused. I hear that some electricity companies require their feed-in tariff customers to install a smart meter (despite the fact that standards for smart meters are yet to be agreed), and then they are tied into that supplier as they can't change until the meter is removed. If you've got a story about metering and feed-in tariffs please share it in the comment section below.

More information about metres and the feed-in tariff from YouGen

Solar electricity information page

Feed-in tariff information page

My electricity metre is running backwards, who is responsible? 

Energy companies confuse customers over export metres for feed-in tariff


If you have a question about anything in the above blog, please ask it in the comments section below.

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26 comments - read them below or add one


Maureen23Comment left on: 31 August 2018 at 2:30 pm


Had 15 panels for 7 years now with no problems,(I understand absolutely NOTHING about them), but the meter from which we send in our readings stopped working for a couple of days recently.

During head scratching efforts to work out why, my husband discovered a difference of 2237 between the readings on the inverter and the feed in tariff meter,the inverter being the highest.

I'm assuming this reflects the difference between my usage and what is being exported? Is that a reasonable figure for 7 years usage of someone who is at home all day using power? 

Meter now working OK after turning off and on several times, though sluggish to start up on damp mornings...could moisture be getting into the system overnight?

Registered from the start with Scottish power ,and no problems with payments excellent company as far as we're concerned.

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Cathy Debenham

Cathy DebenhamComment left on: 4 November 2013 at 9:59 am

Hi Paul

It will depend on how big your system is and how much you manage to use at home. Depending on when your system was installed you only get 3.2p or 4.5p for each kWh you export, and you save around 15p for each kWh you use at home. As you also have to pay an annual fee for the export meter it probably doesn't make sense unless you have a large array. 

The way to find out might be to get one of the more sophisticated energy meters. The Elios4You, for example, will tell you how much you've generated, consumed, bought and exported. Once you've got a smart meter that measures import and export there's no going back. You will be paid on actual export, not on deemed export. 

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paul555Comment left on: 4 November 2013 at 9:09 am

Hi, I am home most days and able to use the "free electric" generated on site for cooking my main meal most days. I also choose the day to use the washing machine / dishwasher and do other domestic chores like lawn mowing and other electric garden/ DIY tools, vacuum cleaning etc. on sunny days and in the middle of the day to use the "free electric".

I was told by my PV installer that I would probably make more by taking advantage of the "free electric" than having an export meter.  From some of the comments and your article it would appear I may have been misinformed.

I'm still trying to work out whether a smart meter will improve my overall payments or lessen them?

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tin tin 1024

tin tin 1024Comment left on: 21 November 2011 at 5:03 pm

If you what to use your excess electricity and save on your electric have a look at this site  about Intelligent Immersion.
Re: Immersion Heater - PV electricity 

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Fred1Comment left on: 4 October 2011 at 12:14 pm

I think the Lady at SSE is incorrect, there should be no losses in the meter. You should be able to get the infrastructure owner in your area to install a meter free of charge. If you want a meter select a FIT player who installs for free all the other payments will be the same.

Good luck



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Adam W

Adam WComment left on: 3 October 2011 at 10:26 pm


I am in the process of setting up SSE as my FiT supplier. On the application form, I asked for the export meter to be fitted (and I switched to them as my electricity supplier).


They initially refused to fit the meter by email whilst I was on holiday. The Monday after I got back, they phoned me and I started talking about false advertising. The lady on the phone interupted me to say she was actually phoning to determine if I qualified for a free export meter. This may have been the case or she may not have wanted me to switch FiT supplier - I believe that the current wholesale electricity price is over 8p/unit meaning it only takes 1400 units to be supplied at 3.1p/unit to cover the £70 cost of fitting a meter.


She did try to disuade me by saying that I would lose about 4 units per day from inefficiencies in the meter. Personally, I can't see how this can be true but has anyone else heard anything about this?



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Cathy Debenham

Cathy DebenhamComment left on: 22 August 2011 at 10:01 am

Hi Grasmere

I've asked your question on the Solar UK forum of linked-in and have had a variety of answers. Below are some extracts: click here to read the whole thread:

[Vince B] 1. Panel mismatching. Most panels nowadays come with positive tolerances - but still some dont. That means a 200W panel with a 5% tolerance can have a value of 190W or 210W - thats a potential 10% difference. The problem arises when you have an array of panels. Not sure how your installers have installed the arrays but basically if one panel in an array is say 190W and the rest are 210W then all will operate at 190W not 210W because the inverters will see all panels as the lowest value.

Good quality installations match the panels - thatis they either use positive tolerance panels (so 200W is at least 200W) or they make sure that the panels are all the same wattage using the flash data.

2. The way the inverters are set up. I wont bore you with technical setails but an inverter will switch on when it reaches its minimum voltage level. Based on the configuration of the strings to the inverter 2 inverters with the exact same panels but with different configurations can produce different outputs

3. Cabling. Most electricians in the UK are AC electricians and dont appreciate the difference between AC and DC (apart from the obvious). Wiring DC is more difficult because the connections have to be exact. If there is any space (and even micro space) between a DC connector then it will arc. Arcing causes losses but more seriously causes fires. If you want to know how much of a fire hazard it can be put a screwdriver across car battery terminals and you will see your screwdriver melt before your eyes

4. AC cabling. Not as serious as DC cabling issues but nonetheless can lead to losses

5. Cleanliness of panels. Any dirt on the panels can affect the output generated as can shading. Even a slight shade on one of the panels can bring down the whole string (see comment on panel mismatching). FOr example a shade affecting one corner of a panel may reduce the efficiency of that panel by 10-20% but that in turn will reduce the overall string efficiency by 10-20%. so it may look like an inocuous shade from your chimney for example - but that can cause a real reduction in permanence.

Unless you have a calibrated cell it is difficult to gauge. However your output should be well known. as a general basis if you go to the PVGIS website and enter your postcode and system size it will give you the expected annual production. This can be broken down monthly to give you an average indication as to what it should be (use simple arithmetic to give you an average daily amount)

You can also find online tools that give a daily summary by postcode of the irradiation in your area so you can check it out, but it is not hard and fast.

The only real way of determining is to get someone to have a look at all the points mentioned above, check the inverter configuration, check the connections etc and if necessary use a Thermal imaging camera and instant production tool to find out what the system is doing. This would measure the instantaneous output at the panels and from that you can determine if the loss is at the panels, the inverter or any other part of the system *it is a tool that looks like a pincer and goes round the cable).

[Mike D] Polycrystalline panels are sometimes called multicrystalline. Without going in to specifics on the systems installed, it appears that your neighbours polycrystalline based system is performing better in the lower light conditions of the UK than your monocrystalline system.

A lot of faith is put into the "efficiency" of the panel, the higher the better is the thinking. But this figure is calculated at Standard Test Condition (STC) of 1000 W/m2 and the UK never gets to these conditions. Polycrystalline panels tend to perform better in lower light conditions. The choice of panel is the most important factor in ensuring that you achieve the highest energy yield possible. The quality of the panel, especially the quality of the cells and the materials used, has a direct impact on the performance of the panel.

[Vince B] Whilst I appreciate panel selection is an important factor having used many different panels over the years - providing you use a quality manufacturer - there is little difference in the panel itself - design is 90% of the battle. and I reiterate that a 200W rated mono and poly will produce similar output over a given time (within a small margin of error)

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davefComment left on: 18 August 2011 at 8:44 pm


I've only had my PV system installed about 4 months, and I signed up with SSE for FIT payments as Atlantic (part of SSE) were my electricity supplier at that time. I am now in the process of switching to another electricity supplier for tariff reasons, and  intend to switch FIT licensee as well in due course, as I have been less than impressed by the SSE FIT team's performance so far, and also because they "aim to make your payment within 65 days" ( yes, that is SIXTY FIVE days) from submitting a FIT meter reading to making a payment. I'm still awaiting payment for the reading submitted at the end of June, so it looks as if they are going to take it to the limit, possibly on the basis that the money is earning them money whilst in their bank account, rather than mine - or is that a cynical view?.

I intend to make enquiries, as recommended on this website, with other FIT licensees to try to assess which will hopefully give me better service. A neighbour has signed up with E.on for his FIT payments, and seems to get very quick payment, and has received a number of free devices for energy saving and monitoring.

 Has anyone else got any recommendations for FIT licensees?

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Colin R

Colin RComment left on: 18 August 2011 at 8:49 am

Hi Huw, Cathy,

I had exactly the same problem as you with my meter running backwards.  Nice to see initially, but, of course, not how it should be.

I told Southern Electric about the problem on the phone (as soon as my system went live), and with my FIT application - that was back in April.  It took them two months to reject my FIT application due to a minor change required on my MCS Certificate (watts vs kilowatts), which my installer did straight away for me, so by return I sent the the new Certificate and, again, told them in writing about my meter.

Two weeks ago, having heard nothing more, I phoned them up - even the call centre agent didn't know what to say about the delay.  They agreed that all was in order, and the the FIT paperwork would be with me in a couple of weeks (still waiting) - and just before they hung up I managed to explain about my meter.  And, hey presto, an engineer came round last week to chage it.

I suspect some of the confusion came about because Southern Electric will no longer install an export meter, even though their FIT application form says they will.  

But, regardless, I'm wondering how they're going to sort out the fact that my old meter was reading less than it did back in April - I can see a long battle coming up.

I did take the view that I'd told them and so it was their problem, but in the end I think you just need to persevere because (certainly for Southern Electric) they're not exactly pro-active.

Good luck! 

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GrasmereComment left on: 9 August 2011 at 10:42 pm


Having been live with my PV since mid June I have wondered how one can tell if it is working correctly, answer, a comparison test with my friends across the road. We both have systems of 3.96kw and both face due south with minimal  shading except at sun rise and sun set, in fact its remarkable how similar our respective sites are. My PV array is a Monocrystaline product fitted to a Sunnyboy Inverter and my friends is a Polycrystaline array also fitted to a Sunnyboy Inverter. Last week end we both took readings from the  respective generation meters at the same times and compared the readings. Over the test period my readings were 15% lower, that is 2.5kw less than the  other system. Over a year this would amount to a large loss. My installers response to my concern was that PV's either work or they don't. not very supportive. can any one confirm my theory that a PV system can under perform if a panel or a wiring line is suspect. The inverter will still convert a reduced DC input if a problem exists. Can one perform any test to confirm the operational status of the arrays.

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Cathy Debenham

Cathy DebenhamComment left on: 8 August 2011 at 7:58 am

Hi Huw

It sounds as though you've tried pretty hard to let your energy company know, and it's down to them whether or not they act on that information at all. Of course, that's not a legal opinion, just a moral judgement. But, it doesn't always seem as if big companies abide by the same ethics, so if it were me I'd do one more back-covering step of writing them a letter - and then stop investing any more energy into it. Has anyone got any stories about this situation - good or bad? My energy company replaced my meter as soon as I told them it was spinning backwards.

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Huw Morgan

Huw MorganComment left on: 6 August 2011 at 4:22 pm

Can anybody help regarding my meter?  I had solar pv installed a year ago and have been getting FIT payments since.  The problem is that the electricity company have not changed my old meter which spins backwards for half the year, so my net usage has been 253kwh for the year for a large house.  I have telephoned them to let them know this (and kept a record of the dates and times), but the call centres are not interested and I just get passed around.  I also wrote on my FIT contract when I sent it in that I had an old meter which was in reverse, but have had no response.  I told the meter reader when he came but it wasn't his department.  I object to spending vast amounts of time on this, but am worried that I will receive a large retrospective bill, in addition to the slightly dodgy ethical issues.  Any advice?

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Cathy Debenham

Cathy DebenhamComment left on: 19 July 2011 at 8:12 am

Hi Hobbes

Sorry for the slow reply - I've been on holiday. For installations under 30kW it seems that the energy company can choose whether or not to install export meters, it's not mandatory. Some will do it - at a cost - others won't: you'll see which is which in this blog. The good news is that you can choose which company you use as your feed-in tariff supplier, and it doesn't have to be the one that you buy your electricity from. The bad news is that whoever you choose, they will want to change the meter that's spinning backwards for a digital one. I suggest you tell them now, to avoid arguments later over how much it's spun back, and who owes who what!

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hobbesComment left on: 11 July 2011 at 8:34 pm

I am still awaiting the FIT contract document to sign and return since PV System install in April.  I requested the then free installation of an export meter have today been informed that Atlantic have made a policy decision not to install them.  My house meter has run backwards and to date has a lower reading than when the syatem was commissioned.  C

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Cathy Debenham

Cathy DebenhamComment left on: 16 June 2011 at 10:57 am

Hi Sally - I agree with you, that it's interesting to know what you're exporting, even if you end up with the deemed rate.

& Malcolm - maybe I'm naive, or just a hopeless optimist, but I think that if you expect the worst from every situation that's probably what you'll end up with, so I carry on trusting!

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Malcolm Comment left on: 15 June 2011 at 2:01 pm

Hi Cathy,

I read with amusement your comment that "it is pretty unlikely to make a retrospective move as it undermines trust in all future Government promises" what trust! if they were running a limited company most of them would be disqualified as directors. As soon as it suits them "fiscal constraints" they will change it just look at pensions, NHS, VAT, weekly bin collections, Etc.





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Sally Daley

Sally DaleyComment left on: 14 June 2011 at 10:03 pm

Thanks for posting helpful information on state of play with export meters.  We switched our 2kWp PV array on at the very end of March.  Our mechanical meter has been going backwards as well as forwards since then.  We are still waiting for our FiT application to be processed.  It seems it will be a while before the meter is changed for one that doesn't go backwards.  In the mean time I guess we are winning in terms of our electricity bills, but we are not now able to record our total weekly electricity consumption, information which we value and use.

We asked our installer if they could fit us something to monitor export and they were initially hesitant because the standard advice they give out is "go with the 50% deemed export".

When I explained I wasn't  bothered about giving the energy supplier the figures, but that I wanted proper feedback for myself they said if we already had an isolation switch or "contractor's switch" between the supply meter and the fuse box, then it would be straightforward and legal for them to fit us a device that would record export, so we are getting a price for that.  We do have a switch already as it happens but they were prepared to fit that for us and get the necessary permission from the energy supplier to fit it, if not.

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Cathy Debenham

Cathy DebenhamComment left on: 12 April 2011 at 2:36 pm

Hi Caloric. That sounds like a good combination, and you certainly do well out of the 50% deeming. As to the point made by Energy Friend, I think that it will vary according to situation what's best to do. Given that I'm at home all day, and tend to put the dishwasher and washing machine on while the sun's out, I thought I would benefit too, but in fact I still export more than half on a 2kWp installation. So, people with a bigger system may find it worth getting an export meter. Southern Electricity seem to to be the only ones fitting them for free at the moment, and I think that's only for existing customers.

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caloricComment left on: 1 April 2011 at 4:37 pm

Just had PV installed with declared net capacity 3.5 kW.  We have an air source heat pump for a swimming pool so I expect to use all the electricity we generate from May to September when we use the pool. So I am happy with the assumption that we export half the power generated. Very pleased to hear the tariff was increased today to 43.3p and the export payment increased to 3,1p per unit.

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Energy Friend

Energy FriendComment left on: 31 March 2011 at 1:57 pm

Hi Cathy and Grasmere,

 You have the choice up front of whether to put the export meter in?  On average UK usage, the difference between estimating 50% export and measuring 100% export is only going to be around £50 a year.  And of course even working away from home you wouldn't be exporting 100% (power for fridge/freezer & weekends etc).

 Not an ideal solution until smart meters are introduced, but my advice would be to accept the 50% and don't bother with an export meter?

 I'd be interested in your views.


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Cathy Debenham

Cathy DebenhamComment left on: 31 March 2011 at 8:58 am


This is interesting ... it obviously varies from supplier to supplier. I feel a little survey coming on! It would be good to find out how it varies between suppliers. 

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mcfi5dhcComment left on: 29 March 2011 at 10:58 pm


 I am a little confused about the cost of an export meter being £70 a year. I have one with SSE, and I pay nothing for it (to my knowledge). SSE installed it on my request over a year ago. Did I fall in a grey area then, and now they charge?

 I get simply the 9p a unit generated (from one meter) and 3p a unit exported (from my MPAN), and thats it. Considering I only get £105ish a year, I would certainly notice.

Thanks, DHC

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Cathy Debenham

Cathy DebenhamComment left on: 29 March 2011 at 8:49 pm

Hi Grasmere

While a future government could move the goal posts for people already signed up to 25 year feed-in tariff arrangements it is pretty unlikely to make a retrospective move as it undermines trust in all future Government promises. In all the recent changes to the feed-in tariff ministers and officials have been careful to emphasise that they will only affect new recipients of the incentive and won't be applied retrospectively.

So, it's never definite, but it is pretty likely to be fine.

I hope that helps.


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GrasmereComment left on: 29 March 2011 at 8:26 pm

I agree with Cathy, I'm considering a 4KW aray and work away from home during the week day light hours, my expected export is very high, EDF say that there is no option unless you wish to pay yearly for a meter maintenance arrangement.Does any one know of a supplier that will pay on a un licenced export meter ??.

Has any one considered the legal standing regarding the 25 year agreement should any future goverment change the rules. Would existing customers be protected but new applications accepted under any new rules. Or does one invest in green technology and risk loosing it all as per any stock market investments.

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Cathy Debenham

Cathy DebenhamComment left on: 29 March 2011 at 11:40 am

Hi Colin

It's not a choice for the energy companies. It's the rules. If there's a proper export meter in place, it must be used. Otherwise export is deemed at 50%. There's not any room for negotiation!

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Energy Friend

Energy FriendComment left on: 29 March 2011 at 11:30 am

Hi There

New member... 

In my experience, energy companies deem the export tariff as being so low that they are happy to estimate it without an actual export meter, as long as you agree a set amount up front (normally 50%).

I would guess putting the export meter in would then confuse matters.

Any other experiences?

Colin Robinson

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