1. Batteries 2. PV comparison

[Dillsue]

Had a quick look at FIT guidance for eleccy suppliers which contains the following-

 

"6.72. Where it is not possible or practical to measure export by export meter readings, export 
should be deemed for accredited FIT installations with a total installed capacity of up to 30kW. 
For the accredited FIT installations where export is permitted to be deemed, the Secretary of 
State determines the percentage of electricity deemed to be exported. Such a determination is 
published at least 1 month before the beginning of each FIT Year."

 

I read that as its obligatory to make deemed payments if an export meter can't accurately measure FIT export. So if you've been on deemed then moved to metered export, all you need to do to move back to deemed is add some none FIT Generation which renders your FIT export meter reading inaccurate. At that point your leccy supplier is obliged to move you back to deemed???

[sharpener]

 

14 minutes ago, Dillsue said:

I read that as its obligatory to make deemed payments if an export meter can't accurately measure FIT export. So if you've been on deemed then moved to metered export, all you need to do to move back to deemed is add some none FIT Generation which renders your FIT export meter reading inaccurate. At that point your leccy supplier is obliged to move you back to deemed???

 

No, the FIT meter is not an export meter at all. It is a Total Generation Meter connected in series with the PV system and nothing else. Deemed exports are simply 50% of this reading. Actual exports are of necessity measured at the grid connection point with a different meter. Not surprisingly you cannot claim both. The irreversibility of giving up deemed exports is I think a regulatory decision not a technical one, it is IMO to encourage people to move away from the FIT thinking now it is a legacy technology.

 

There are several different scenarios. Can you post a link to the schematics you mention below?

 

7 hours ago, Dillsue said:

look up the OFGEM guidance for FIT generators and either the guidance for generators(you or me) or FIT payers(electric Co.)  includes schematics on allowable configurations for battery hook up.

 

My situation is I have an old radio teleswitch two-rate E7 meter, and AC-coupled PV installed in 2011, which earn the FIT payments as measured by a separate Total Generation Meter.

 

I also have DC-coupled PV installed later which goes straight into the 48V battery and can in theory be exported via the DC-AC bidirectional inverter. However my DNO does not allow more than 16A total export hence my system is set up so this comes preferentially from the AC-coupled PV to make sure it clocks up on the TGM, from which I get paid for the amount generated plus deemed export.

 

If you give up the deemed export tariff you are then allowed to earn express export payments, so if Octopus can fit me a working smart meter (doubtful) then the export component (15p/unit under Octopus Outgoing) will be measured by its export register but the generation component (68.3p/unit) will still be measured as before by the TGM and paid to me by Good Energy under a quite separate contract.

 

IIRC @JamesPa is in a different position, he also has similar AC-coupled PV and is looking to add more, somehow, and export it via his SMETS2 meter. [It is important in this situation not to do anything which adds to, tees into or alters the wiring between the PV inverter and the TGM as this is understandably reckoned to be a no-no and may disqualify you.]

 

 

 

[SteamyTea]

2 minutes ago, sharpener said:

It is a Total Generation Meter connected in series

Or in parallel  but with polarity reversed.

[Dillsue]

9 minutes ago, sharpener said:

 

 

No, the FIT meter is not an export meter at all. It is a Total Generation Meter connected in series with the PV system and nothing else. Deemed exports are simply 50% of this reading. Actual exports are of necessity measured at the grid connection point with a different meter. Not surprisingly you cannot claim both. The irreversibility of giving up deemed exports is I think a regulatory decision not a technical one, it is IMO to encourage people to move away from the FIT thinking now it is a legacy technology.

Your correct, the FIT Generation Meter measures generation only. It's used for generation and deemed export payments.

 

If you're on metered FIT export, then that's done by the premises smart meter. If you've got FIT and non FIT generation going through the export meter then it's not possible to measure the FIT element so you go onto deemed payments. No mention of how you've been previously paid in the Ofgem guidance.

[Dillsue]

21 minutes ago, sharpener said:

IIRC @JamesPa is in a different position, he also has similar AC-coupled PV and is looking to add more, somehow, and export it via his SMETS2 meter.

All he needs to do is add panels to the FIT system and change the inverter if it can't handle the new DC input. Declare the additional generation capacity and get paid pro rata for the existing generation meter. Simples!

[JamesPa]

9 minutes ago, Dillsue said:

All he needs to do is add panels to the FIT system and change the inverter if it can't handle the new DC input. Declare the additional generation capacity and get paid pro rata for the existing generation meter. Simples!

In principle yes.  Actually it's not in principle even necessary to change the inverter, because it can handle the new DC input.  A bit of clipping at peak hours in peak

months but nothing worth worrying about until the inverter needs renewing anyway.

 

Now try finding anyone to quote for that in the south east of England!  The issue again is not the technology, it's the marketplace.

Edited May 10 by JamesPa

[sharpener]

31 minutes ago, Dillsue said:

If you're on metered FIT export, then that's done by the premises smart meter. If you've got FIT and non FIT generation going through the export meter then it's not possible to measure the FIT element so you go onto deemed payments.

 

You don't need to measure the FIT and non-FIT exports separately. They both earn the same so no need to distinguish between them. Or revert to deemed exports. If deemed exports paid more you would not have given them up in the first place but at the current rates above they don't.

 

You need to keep the TGM to measure the generation component, that can't be done at the normal metering position.

 

You could in theory deduct the TGM readings from the smart meter exports so the original FIT contract (Good Energy) pays for the FIT exports, and the export contract (Octopus) pays for the non-FIT exports, but that is not what they do.

 

14 minutes ago, JamesPa said:

Now try finding anyone to quote for that in the south east of England!

 

Yes, I contacted ?20 companies before I found one that would install more panels on an existing inverter. Eventually there was one that sent ppl down from Grimsby to do it but dealing with their office was a nightmare so I would not recommend them.

 

 

Edited May 10 by sharpener

[Dillsue]

48 minutes ago, sharpener said:

There are several different scenarios. Can you post a link to the schematics you mention below?

 

 

 

Try this https://www.ofgem.gov.uk/publications/guidance-generators-co-location-electricity-storage-and-hydrogen-production-under-ro-fit-rego-and-seg

[Dillsue]

8 minutes ago, sharpener said:

 

You don't need to measure the FIT and non-FIT exports separately. 

I think you do!!

 

Non FiT generated eleccy isn't eligible for FIT export payments so you have to be able to identify the FIT element and the non FIT element which you can't do if they are running through a single meter. They definitely dont earn the same payments.

Edited May 10 by Dillsue

[Dillsue]

27 minutes ago, JamesPa said:

Now try finding anyone to quote for that in the south east of England!  The issue again is not the technology, it's the marketplace.

Get a roofer to fit the rails and panels and plug them into the existing system yourself. No spark needed as they are all factory assembled and tested- same as an IKEA table lamp which you don't need a spark to plug in.

Edited May 10 by Dillsue

[sharpener]

6 minutes ago, Dillsue said:

Non FiT generated eleccy isn't eligible for FIT export payments

 

They are both eligible for export payments and at the same (generic) rate, that is why they can go through the same (smart) meter.

 

Non-FIT PV is not eligible for FIT generation payments which is why it can't go through the TGM.

[Dillsue]

48 minutes ago, sharpener said:

 

They are both eligible for export payments and at the same (generic) rate, that is why they can go through the same (smart) meter.

 

Non-FIT PV is not eligible for FIT generation payments which is why it can't go through the TGM.

So who's paying for the eleccy from my self installed array....legitimately??

 

FIT?- not MCS= no payment

SEG?- not MCS= no payment

Octopus outgoing?- not jumped through their hoops= no payment

 

So who's paying?

[SteamyTea]

1 minute ago, Dillsue said:

So who's paying

You are.

[sharpener]

50 minutes ago, Dillsue said:

Try this https://www.ofgem.gov.uk/publications/guidance-generators-co-location-electricity-storage-and-hydrogen-production-under-ro-fit-rego-and-seg

 

Thanks. I think the confusion is cleared up by these paras

 

4.5. Alternatively, FIT installation owners can decide to opt out of receiving FIT export
payments and may seek to sell their exported electricity through a power purchase
agreement (PPA) or similar commercial arrangements.

 

4.19. Where storage is co-located and it is not possible to identify whether the export meter
measures export from the accredited FIT installation or another ineligible source, such
as stored electricity imported from the grid or another generation source, the generator
will not be entitled to export payments. However, generators of such installations may
secure other revenue streams, such as a power purchase agreement (PPA) or similar
commercial arrangements to continue receiving revenue from the electricity they are
able to export.

4.20. Please note that most smart meters are not “bi-directional meters” under the definition
we use here. This is because even though they are capable of measuring both import
and export, they do not generate a net value.

 

So if you opt out of deemed exports in favour of a PPA then technically they are no longer FIT export payments at all which is why they earn at the same rate as your non-FIT generation. And under a PPA e.g. Octopus Outgoing you are also allowed to arbitrage by selling them back power you have bought at a cheaper rate.

[JamesPa]

1 hour ago, Dillsue said:

Get a roofer to fit the rails and panels and plug them into the existing system yourself. No spark needed as they are all factory assembled and tested- same as an IKEA table lamp which you don't need a spark to plug in.

I have been wondering about that.  Will roofers do this sort of thing as a standalone job.  Strictly also it needs MCS to retain the fit payment (about 45p per generated unit). The generation will go up quite a bit so the fact it's been done is detectable

[Dillsue]

1 minute ago, JamesPa said:

I have been wondering about that.  Will roofers do this sort of thing as a standalone job.  Strictly also it needs MCS to retain the fit payment (about 45p per generated unit). The generation will go up quite a bit so the fact it's been done is detectable

No MCS needed for the extension unless you want to claim SEG on the additional generation. Once you've added capacity notify your FIT payer and they'll be expecting a jump in generation and pay you pro rata for the proportion generated by the registered FIT capacity

[sharpener]

35 minutes ago, JamesPa said:

I have been wondering about that.  Will roofers do this sort of thing as a standalone job.  Strictly also it needs MCS to retain the fit payment (about 45p per generated unit). The generation will go up quite a bit so the fact it's been done is detectable

 

The new generation will be excluded by the "apportionment" process so you will not get FIT payments on it anyway. So if the original (MCS) installation is unchanged it is not clear why you would need MCS on the new one as it is not eligible for FITs.

 

Perhaps you mean about registering with Octopus for their Outgoing tariff? I don't know if they would accept the certificate you already have, it would be some time before they worked out you are exporting more than its rated capacity if indeed you ever do. [For comparison my original installation could theoretically export about 4MWhr/yr but my actual export from both is in fact only 2.8 because of the self-consumption (which they cannot check) so the additional capacity would be undetectable.] The longstop position is their self-certification scheme which will cost you £250 plus the cost of a structural engineer's report on the roof.

 

Edit: the above is a good reason to have different cos for your FIT payments and the export tariff. There is a central database though so get the export tariff set up before you add the capacity.

 

BTW have you got your mind round my schematic yet <g>?

 

 

Edited May 10 by sharpener

[JamesPa]

10 minutes ago, Dillsue said:

No MCS needed for the extension unless you want to claim SEG on the additional generation. Once you've added capacity notify your FIT payer and they'll be expecting a jump in generation and pay you pro rata for the proportion generated by the registered FIT capacity

I think MCS is needed unfortunately because output goes through existing inverter and thus existing generation meter.  Afaik this needs MCS to certify the capacity change on change of system.

 

This itself is interesting, the capacity is defined as the peak and since it is now and will be inverter limited, apparently the capacity as defined is unchanged, even though the total generated amount will.  However because the system has changed MCS still needs to certify it.  At least that's how I read the regs on modifying s fit eligible system (unless they have changed in the last 12 mo).

 

Also the panels are daisy chained into the inverter so are plugged together on the roof.  I'm surprised a roofer would touch 400V DC.

Edited May 10 by JamesPa

[Dillsue]

1 minute ago, sharpener said:

 

The new generation will be excluded by the "apportionment" process so you will not get FIT payments on it anyway. So if the original (MCS) installation is unchanged it is not clear why you would need MCS on the new one as it is not eligible for FITs.

With MCS the extension is eligible for SEG or a direct route to Octopus Outgoing. Without MCS youre not eligible for anything. The original capacity remains eligible for FIT regardless of who installed the extension. 

[Dillsue]

4 minutes ago, JamesPa said:

I think MCS is needed unfortunately because output goes through existing inverter and thus existing generation meter.  Afaik this needs MCS to certify the capacity change on change of system.

All generation goes through the generation meter and you get paid a proportion related to the proportion of existing FIT capacity and new extension. No MCS needed to retain your FIT payments on the original capacity. Only need MCS if you want SEG or Outgoing on the extension capacity. Read the section on extensions in the guidance I linked to earlier.

[JamesPa]

8 minutes ago, Dillsue said:

With MCS the extension is eligible for SEG or a direct route to Octopus Outgoing. Without MCS youre not eligible for anything. The original capacity remains eligible for FIT regardless of who installed the extension

My reading of the rules is that, because the existing system is being modified (and the new generation goes through the same generation meter), I need MCS certification of the system as modified.  The fit payments are then made based on the generation meter reading adjusted by the ratio of (MCS certified) generation capacity.  If this isn't the case are you saying the rules allow me to self certify the new generation capacity for the fit calculation.  That seems improbable.

Edited May 10 by JamesPa

[Dillsue]

10 minutes ago, JamesPa said:

Also the panels are daisy chained into the inverter so are plugged together on the roof.  I'm surprised a roofer would touch 400V DC.

I'd be surprised if anyone would touch 400vdc as all plugs are IP2x rated. Anyone would have to try hard to touch the live bits of an MC4 connector.

 

You'd have to ask your roofer, or you plug em in

 

[Dillsue]

16 minutes ago, JamesPa said:

My reading of the rules is that, because the existing system is being modified (and the new generation goes through the same generation meter), I need MCS certification of the system as modified.  The fit payments are then made based on the generation meter reading adjusted by the ratio of (MCS certified) generation capacity.  If this isn't the case are you saying the rules allow me to self certify the new generation capacity for the fit calculation.  That seems improbable.

See section 6.8 of this https://www.ofgem.gov.uk/publications/feed-tariffs-guidance-renewable-installations

 

Accreditted = MCS

Non accreditted= non MCS

[Dillsue]

50 minutes ago, sharpener said:

So if you opt out of deemed exports in favour of a PPA then technically they are no longer FIT export payments at all which is why they earn at the same rate as your non-FIT generation. And under a PPA e.g. Octopus Outgoing you are also allowed to arbitrage by selling them back power you have bought at a cheaper rate.

Again your correct that if you opt out of FIT deemed payments for PPA(Octopus Outgoing) then yes you have forgone your right to FIT payments both deemed and metered. But what is being said is about opting out of FIT deemed payments for FIT metered payments, not PPA.

[sharpener]

1 hour ago, JamesPa said:

This itself is interesting, the capacity is defined as the peak and since it is now and will be inverter limited

 

If the capacity is already limited by the inverter rating what do you gain by adding more panels?

 

Yes there is some advantage by over-panelling a bit wrt the inverter (20% is often suggested as optimal and my second set is a bit under 10%) bc you get more at the shoulder periods of the day and in winter.

 

However I thought you were talking in terms of a lot more and if you are already over-panelled as you imply I don't quite see the benefit, can you share the numbers?