Existing FIT System Metering

Hi, I have an existing FIT system with it's own metering that's been installed and working fine for 5+ years.
I've now installed a new Hybrid inverter and a 9.5kw battery that's all working as it should with an EM115 CT clamp. My problem is that the FIT meter is now recording the solar and the battery energy usage! When the batteries are in use in the evening, the FIT meter is still recording.
I'm assuming I need to change the meter over, but with what?

My current setup has one EM115 installed with it's clamp around the live incoming mains tail.

But I've seen an example that uses 2 x EM418, as shown here

I've also see information about using a Bi-directional meter, but i'm not sure what one to use.

Can anyone help?

Thanks
Martin

Surely you should have used an AC inverter rather than a hybrid inverter with a retrofit. Or did you replace the original inverter with the hybrid?

Either way the installation is wrong if the FIT meter is recording Battery discharge as well as PV generation.

Furthermore, if you a getting FIT payments based on that meter it will probably trigger an investigation and visit by your FIT organisation as your generation numbers will be well out of range for your registered installation. I suppose you could even be accused of fraud so I would document everything and get the installers back to sort it out.

I've posed the wrong image above, please see the 2 x EM418 meters here

2 x EM418, as shown here on the second page (Schematic-01
Hybrid with 2 x EM418) [https://zerohomebills.com/wp-content/uploads/GivEnergy-Solar-Battery-Technical-Data-Schematics.pdf](https://)

cluelesscris Thanks for the reply, the batteries were only installed a week ago, so the meter's not over clocked too much, and i've kept photos all the way.
Yes the original inverter has been changed for the new Hybrid one.

Have you replaced your original fit inverter when you installed the battery? Or have you installed additional PV and a hybrid inverter? Have a look at your fit contract wrt changes.

Yes, the original FIT inverter has been replaced for the Givenergy Hybrid one

I can't see how the hybrid can work correctly with a FIT meter as it only has one AC outlet - there is no way for external, physical verification of PV generation alone. Here I'm assuming your FIT is also a deemed export tariff and not actually a SEG tariff which can be run through a smart meter.

I'm ready to stand corrected but if you have a decent deemed FIT (my system is 11 years old so I currently get 64p per KwH generated) then you should have had an AC3 alongside your existing inverter to keep things in line. For your sake I hope I'm wrong...

mwoodage Well done for identifying that there is an issue. It looks like your installer missed the fact that you are on an existing FIT tariff and AFAIK any changes to the installation needs to be notified to your FIT supplier. Because you have added a battery, your "deemed export" could be significantly higher than without a battery.

I've not had any experience of this before but FWIW, if it was me, I'd contact the FIT supplier and explain what has happened. If the PV hasn't been changed, just the inverter and the additional of a battery, they might agree to pay FIT based on historical readings (ie an average of what you have been receiving each year to date) or another formula. Worst case scenario is that they refuse to honour the agreement because the installation has been modified other than replacing like with like, but personally, I'd rather accept the loss of FIT payments than end up getting into trouble further down the line. A real pity your installer didn't advise you to discuss this with the FIT supplier beforehand.

I think to keep your FIT you need to put the battery on an AC3 and get the original inverter put back.

If the inverter had gone pop then you can get a similar inverter to replace it with approval of FIT.

Agree with what has been said above. By changing your inverter (to a hybrid) your installer would have invalidated your FIT contract. When we had our second PV system & battery installed, we ensured that they were completely separate from the original FIT PV system to ensure we did not loose the FIT payments.
Best advice is to get your installer back to re-install the original inverter (or an equivalent) and feed the battery through an AC3.

Did the installer ask about FIT, or did you tell them?

Not sure whose mistake it is! E.g. would they replace the hybrid inverter for no extra cost?

It does seem like uninstall or give up FIT are the only options. Doubt an estimated generation would be acceptable. You'll also need to contact ofgem I think, as well as your FIT supplier/provider.

Wonder what the loss in earnings would be for the FIT contract?

If you do end up giving up FIT you can at least register for SEG payments for anything you export.

It’s cheaper to buy two new inverters than loose FIT payments

kram guess it depends on the size of the system and the number of years left.

TX200

Well the FIT didn’t come in that long ago and if the system is that old you should toss the 200w (degraded output) panels and replace them with modern shade efficient 400kWp ones.

Why would you get rid of an income stream when you can buy and AC coupled battery and not lose it?

I guess it could be borderline but most people I know with FIT either get high payments for old kit or have a long time left to run.

cluelesscris
I don't think that you are right here. My understanding is that a bidirectional meter solves the problem :

GENERATION = PV Generation
IMPORT = Grid energy imported to Battery via Inverter from consumer unit
EXPORT = Total energy from Inverter to consumer unit (PV + discharging battery)

EXPORT - IMPORT = GENERATION

If you can measure the total energy that comes from the inverter and the total that goes to the inverter, using a bidirectional meter, you can calculate your PV generation. (I believe you would also be subtracting the power used to run the inverter here, but that would be a small loss, a rounding error in the grand scheme of things, so have not checked)

The stipulation by OFGEM is that the meter fitted must be able to display this net number ie. you can't do the calculation manually, you must be able to press a button on the meter to display the correct generation value.
As far as I can tell, the EM115 does not meet these criterion.
Also you must notify your FIT licensee of the changes, take a picture of the old meter and the new meter, and provide them with a schematic of the new set-up for them to approve (your installer ought to do this part)

Although it is too late in this instance, I believe it is also possible to get pre-approval of your proposed installation.
Clearly, you must stick with to an inverter the same size as your original one in all instances

Re GivEnergy specifically, I've seen that 2xEM418 schematic too @mwoodage , but have been told by a couple of installers that they are not sure why 2 meters are needed, and that a single bidirectional one ought to suffice. I'm yet to get a clear answer here.

I don't believe this affects any deemed usage payment, but I have not dug too deep here as I'm not concerned about losing the export payment in a worst case scenario ( it's peanuts compared to the generation on older installs obviously)

The details of how the EPS interacts with this set-up, if at all, are also unclear to me at this stage.

Please correct me if I have taken a wrong turn at some point - I went deep into it, and this is the conclusion I reached, confirmed by two installers, but we are all fallible, sometimes when we are at our most confident 😉

phoenix The hybred takes DC from the panels and pushes out AC to the meter through the same cable as the AC inverted from the batteries. In this case the issue is that you cannot differentiate PV generation from Battery dump. Everything is in one direction. Furthermore, the true PV generation is 'lost' into the battery when it charges.

cluelesscris

cluelesscris The hybred takes DC from the panels and pushes out AC to the meter through the same cable as the AC inverted from the batteries. In this case the issue is that you cannot differentiate PV generation from Battery dump. Everything is in one direction. Furthermore, the true PV generation is 'lost' into the battery when it charges.

This is all correct, but also I believe, not relevant:

1) If you didn't have a battery, all the inverter output would correctly show up as PV Generation

2) If you only charged the battery from the inverter, you would be holding back a maximum of the battery capacity until you discharged it, so all you are doing is delaying the time that is shows up on the generation meter, not changing the total once the battery is empty. Yes, any conversion losses from charging/discharging the battery will also be missing from the generation total, so you would 'lose' that from your FIT payment
So, in this scenario, the generation meter would show an (almost) accurate reflection of your PV generation

3) The complication is introduced when you add grid charging, as that will show up on the generation meter upon discharge, and be indistinguishable from the PV generation as you say. As such you need to have an accurate measure of this to subtract from the total output from inverter to consumer unit, leaving you with the (almost) accurate PV generation total again.

Battery dump is indistinguishable from PV generation at the meter, but this is not the real issue - the issue is charging from the grid, and that energy incorrectly showing up generation if not accounted for.

What am I missing?

phoenix Nothing - but with the last two paragraphs you hit the nail on the head. I wasn't aware the meter can calculate the net generation as required. If it does then all it would need is approval from FIT operator. Any readings now sent for FIT would be out of sequence with previous readings which would probably trigger a hard reading (man with a van) anyway.

cluelesscris

cluelesscris I wasn't aware the meter can calculate the net generation as required

Not all meters can. E110 can't (simple unidirectional), EM115 can't (bidirectional but doesn't give a net reading), EM418 appears to, and is what GE specifically instruct for this scenario in their installation guides. I don't understand the need for 2 of them though.

cluelesscris If it does then all it would need is approval from FIT operator

Correct. FIT operator needs to approve the new schematic and the functionality of the new meter

cluelesscris Any readings now sent for FIT would be out of sequence with previous readings which would probably trigger a hard reading (man with a van) anyway

In the first answer I laid out what need to be done to avoid this. When the new meter is installed a final meter reading must be given to yout FIT operator, then you start from zero with on the new one. A registered installer providing this information I believe negates the need for an inspection and there should be nothing unusual about the ongoing generations totals that would trigger one.

FWIW I also spoke to my FIT operator about it. They told me their general requirements, but obviously were not able to comment on specific systems. They also suggested getting the schematic approved by them beforehand if I was in any doubt.

phoenix Thanks for your input. I learned a few things from it. Always a good thing.

cluelesscris

You're welcome, I hope I can save a few people the headaches I endured to get to what I think is the answer!

phoenix Well done looking into this. Your analysis of using a meter with both import and export registers to calculate PV generation is a fix that anyone with FIT can use to update their installation to one with a hybrid inverter with attached battery. Another post elsewhere also suggested that an existing FIT installation can have PV added as long as the FIT operator agrees to it (FIT payments continuing pro-rata). Good news all round. @mwoodage just needs to get his installer to backfit this solution after getting FIT operator agreement.

This suggests that as long as you get agreement in principle from your FIT operator, you can modify your existing FIT installation to increase PV and change your AC-connected inverter with a hybrid and battery without losing FIT payments.

BTW @mwoodage if you do fit a dual-register meter, it might be worthwhile looking for one that can provide remote meter readings (similar to a smart meter with IHD) which you could include in any home automation. Our MCS meter is in a very inaccessible place but is there only for compliance purposes as FIT isn't an issue for us.

Tim
Thanks! Yes it does.
That is interesting re extra panels as the battery would potentially be zero vat rated if installed with extra PV fitted at the same time. Another rabbit hole to dive down ...

I hope @mwoodage pops back in and see all this

For anyone that is interested, most of the required information is required in the Ofgem Colocation Guidance document linked below
P35, Scenario 4.2, seems to be the simplest version of what we are looking at - one bidirectional meter to calculate generation, for use with deemed export payments.
Glancing at it again today, I think the 2 meter set-up recommended by GE is one that allows for Export metering instead of deemed export. If anyone digs deeper into this and can confirm/correct this, please report back.

[https://www.ofgem.gov.uk/publications/guidance-generators-co-location-electricity-storage-facilities-renewable-generation-supported-under-renewables-obligation-or-feed-tariff-schemes-0]

EDIT: Right, I think I've got it. In order to qualify for export metering, you need a second meter that can isolate the amount of electricity that is exported solely by the FIT installation. In theory without this you could charge the battery from the grid, discharge it back to the grid and incorrectly claim payments for export that was not generated by the PV.
Whether the 2xEM418 meets this requirement, I do not know.
See P39 Scenario 4.6 for more on this.

Hi I typed this up a while ago to explain some of the issues and you have seemed to got to the point where you know you have a problem and will have to do some leg work to solve it.

https://www.speakev.com/threads/solar-fit-payments-and-batteries.164161/#post-3125292

This thread is perhaps too late for you but if anyone else is looking at a Hybrid and Fit payments it might help?

Good luck on your journey in solving it.

M_J t=you cant read that without creating an account.

Well I think it might be worth creating an account as lots of useful comments from other posters about the whole process. BTW a very good community to so you might find it useful as lots of EV owners have batteries too...

When batteries are installed you are required to inform your FiT provider. Mine wanted a wiring diagram of the battery installation and I had a to sign to say the FiT PV configuration and meter hadn't been touched - we have a completely separate AC inverter for the battery.

The key thing is that it must still be possible to measure the PV generation in isolation of anything else. I think I've seen others get this approved by using a two way generation meter - but can't see how that can differentiate between Solar vs Batter export?

GrahamRead can't see how that can differentiate between Solar vs Batter export

The "import" all goes to the battery and the "export" comes from the inverter. If you subtract import (battery charge) from export (battery discharge + PV), you nett off the solar for which you can get FIT payments.

Tim ok, but how do you know the solar without a meter ?

GrahamRead The whole premise of this is that the original MCS meter be replaced with a meter that has separate import and export registers. The existing energy supplier meter wouldn't be touched, just the MCS meter between the PV and home consumer unit. Old style induction disk meters used to go backwards when exporting but modern digital meters have separate registers for energy flow in each direction. Therefore the energy import (to charge the Givenergy battery from grid) would register on the new digital MCS import reading and the energy flow from the Givenergy hybrid (energy generated by PV and energy discharged from battery whether charged from grid or PV) would register on the export reading. Subtracting import from export on the new digital MCS meter provides a figure for PV generation, albeit slightly lower than actual due to inverter losses to charge and discharge the battery.

mwoodage
Hi Martin, I think I have the same problem,
During April 2022 I had a new 3.5 hybrid Inverter with an 8.2k/w battery to my existing array from 2012 and the original generation meter was left in
I'm currently on a Feed In Tariff which I have to submit quarterly readings. The last quarter readings were contested by my FIT Provider as having doubled compared with previous years and on checking they're correct. They asked if I had a Bi-directional meter fitted (which I didn't know) as the readings from the original meter could become distorted when I download from the grid.
I contacted the installers who kept me waiting for over 3 months before they sent someone around to assess the problem. Apparantly an EM115 was fitted within the original PV's system fuse box which was never explained to me and they said this was the 'Bi-Directional Meter'.
I've looked at the different screens from the EM115 but am confused as to which reading i need to submit. However on reading your account of things did you resolve the problem and can I ask which method you used as this is all too far above me. I'm currently trying again to get the installer back to fix this but probably a successful solution would be a way forward and greatly appreciated
Kind regards
Steve

STEVEPERRY If the EM115 is different from the EM115 fitted between the house consumer unit and the DNO fuse, then it should be suitable. The "PV" EM115 probably isn't integrated to your web portal but you can manually read import and export from the meter and net the two to provide your "export" figure. The registers loop round on the LCD and are Total Active Energy, Import Active Energy and Export Active Energy. Total Active Energy is the sum of the other two registers. As long as it's connected the right way round, Export Active Energy should be greater than Import Active Energy; subtract the smaller from the larger and that's your export figure (even though it may have been consumed in-house, hence 50% deemed export for FIT).

Hi Tim, thanks for your reply, after months of badgering the installers they finally fitted the 'Bi-Directional Meter' yesterday which is an Emlite EM23 ECA2.nv. this apparantly (as I'm told) will do the the job for the necessary FIT readings which is all I want to do.
Thanks again to you and for everyone else who contributed their advice regarding my situation, I hope this meter wont cause me any problems.

Cheers
Steve

STEVEPERRY
Worth checking the installer wired it the right way round. The instructions with the meter have an addendum which states a small wiring change. The small wiring change is to wire it the other way round !!!!. My installer didn't read the small print, so mine is import export swapped, "luckily" have no fit payments ....

STEVEPERRY We have the same meter albeit a slightly different model. Ours has no buttons on the front, so although it registers import and export, you can't tell which is being displayed and you can't change the display. As @justpassing says, if it's not wired the right way round, you'll be providing figures for AC battery charge. If it is wired the right way round, you will be providing figures for solar to the home plus battery discharge, which isn't right either. If you can't toggle between registers, this meter (IMO) won't do what you want. In order to supply FIT readings to your supplier, you will need to deduct the import (battery charge) from your export (solar + battery to the house). If you can't toggle to read registers, you're actually worse off than the EM115 you had. I'm afraid deducting one register value from the other is the only way to get to your actual solar generation for FIT payments.

Tim might be different versions, but mine cycles between import export and net, with a small dash indicating which reading.