DIY battery storage commissioning

[nowty]

Forgot to mention, that I have already got an approval for the fast track battery storage which I believe is G99. As I have an existing PV, they gave me an extra 3kw export limit for the battery. So I can now export 6.68kw max. Not that I will be exporting from the battery anyway as I am on the 50% FIT pv export scheme, and taking a smart export tariff means I have to forfeit it.

Yes, by the time you have jumped through the SEG hoops (which require an MCS certificate - which by definition I have not got) it is not worth it if you are on the 50% deemed export already.

Lucky you for the extra allowance and the fast track, which DNO is that, would love to know?

WPD were very risk averse and insisted on a full long-form G99 application, with my 5 kVA Victron turned down to 3.68 kW max inverter power and G100 export limitation to a total of 3.68 kW for everything - including the 3.68kW of my original PV. Depends on the locality I suppose but I am only 100m from the s/station, what do they use, wet string?

Your post about this on another thread really threw me.

The bit about the DNO insisting on a max PV of 3.68kW attached to the Victron (as well as a 3.68kW output limit). But I later read that Victron has something called the "The Factor 1.0 rule" which may explain it but it's the first practical intervention on the DC side by a DNO I have heard about.
https://www.victronenergy.com/live/ac_coupling:start

[Kenny000666]

Forgot to mention, that I have already got an approval for the fast track battery storage which I believe is G99. As I have an existing PV, they gave me an extra 3kw export limit for the battery. So I can now export 6.68kw max. Not that I will be exporting from the battery anyway as I am on the 50% FIT pv export scheme, and taking a smart export tariff means I have to forfeit it.

Yes, by the time you have jumped through the SEG hoops (which require an MCS certificate - which by definition I have not got) it is not worth it if you are on the 50% deemed export already.

Lucky you for the extra allowance and the fast track, which DNO is that, would love to know?

WPD were very risk averse and insisted on a full long-form G99 application, with my 5 kVA Victron turned down to 3.68 kW max inverter power and G100 export limitation to a total of 3.68 kW for everything - including the 3.68kW of my original PV. Depends on the locality I suppose but I am only 100m from the s/station, what do they use, wet string?

It is UKPN

Loads of houses in my area have installed EV chargers, and as I understand it they run at 7kw for hours. Not sure why DNOs make a big fuss over a possible export of 6.68kw.

[Andy]

The bit about the DNO insisting on a max PV of 3.68kW attached to the Victron (as well as a 3.68kW output limit). But I later read that Victron has something called the "The Factor 1.0 rule" which may explain it but it's the first practical intervention on the DC side by a DNO I have heard about.
https://www.victronenergy.com/live/ac_coupling:start

The factor 1.0 does not apply to the dc side. It is for inverters installed alongside the victron. It is also the size of the inverter output and not the oversized panels connected to said inverter. They updated the documentation after I queried it.

“There is no Factor 1.0 limit that applies for DC coupled PV through a Victron MPPT. ” from further down the document. The mppt trackers respond fast enough it is not a problem. The factor 1.0 rule is to protect household equipment/ the inverter when the grid fails. The Quattro raises the frequency to cause the other inverter to shutdown. This takes time.

[nowty]

The bit about the DNO insisting on a max PV of 3.68kW attached to the Victron (as well as a 3.68kW output limit). But I later read that Victron has something called the "The Factor 1.0 rule" which may explain it but it's the first practical intervention on the DC side by a DNO I have heard about.
https://www.victronenergy.com/live/ac_coupling:start

The factor 1.0 does not apply to the dc side. It is for inverters installed alongside the victron. It is also the size of the inverter output and not the oversized panels connected to said inverter. They updated the documentation after I queried it.

“There is no Factor 1.0 limit that applies for DC coupled PV through a Victron MPPT. ” from further down the document. The mppt trackers respond fast enough it is not a problem. The factor 1.0 rule is to protect household equipment/ the inverter when the grid fails. The Quattro raises the frequency to cause the other inverter to shutdown. This takes time.

Thanks for the clarification about it does not affect DC coupling with charge controllers (Victron MPPT in your words), but it's still an interference from the DNO about the DC side of a grid tie inverter (AC coupled) which I have never before heard of.

[sharpener]

WPD were very risk averse and insisted on a full long-form G99 application, with my 5 kVA Victron turned down to 3.68 kW max inverter power and G100 export limitation to a total of 3.68 kW for everything - including the 3.68kW of my original PV. Depends on the locality I suppose but I am only 100m from the s/station, what do they use, wet string?

Your post about this on another thread really threw me.

The bit about the DNO insisting on a max PV of 3.68kW attached to the Victron (as well as a 3.68kW output limit). But I later read that Victron has something called the "The Factor 1.0 rule" which may explain it but it's the first practical intervention on the DC side by a DNO I have heard about.
https://www.victronenergy.com/live/ac_coupling:start

It's more complicated than that. The "1:1 rule" is a red herring, it is there to ensure that PV connected on the AC-Out side of a Victron has somewhere to go in the first 20ms in the event of a power cut (over a few seconds the Victron will then increase the system frequency to shut the PV inverter down). Control of the DC side is different, I don't have any at present* but it is where the new panels will go, they will have an MPPT charge controller which the inverter can shut down over the LAN.

* Edit: emphasis added, I think this may be where the original misunderstanding is. I see Andy has posted along similar lines while I was writing this.

In my case the DNO should not care what I have attached to the back of the Victron because everything it does or does not export comes out of the front. This lack of understanding is not helped by the fact that none of the installation examples in the IET Code of Practice shows the type of inverter that has separate input and output ports (even though there was a Victron rep on the list of consultees).

They have got confused between 3 different 3.68 kW limits:

#1 The existing PV - which is attached to the back of the Victron so they cannot see it at all.

#2 The power rating of the Victron in inverter mode - which is 5kVA, but only 4kW real power anyway. This is the power that comes from the battery and goes out the back into my consumer unit, it is only additive with #1 in the sense they are both available to power my loads. They want me to turn it down to 3.68 which is not much of a sacrifice but if I had wanted the 8kVA model it would have been a problem.

#3 What the Victron can actually export out of the front to the grid, which is the only thing IMO which they have a legitimate concern about, this is subject to the G100 Export Limiting Scheme which is configured quite separately from #2.

It is UKPN

Loads of houses in my area have installed EV chargers, and as I understand it they run at 7kw for hours. Not sure why DNOs make a big fuss over a possible export of 6.68kw.

Yes, it is of course complete and utter nonsense. If I have the cooker turned nearly full on, and then I put another ring on and the 40A mcb trips, the resulting load step is exactly the same as if I decide to export 9.6kW all of a sudden.

How can the DNO distinguish between these two scenarios? For a given supply source impedance they will both result in identical steps in the line voltage which is the thing they say they are most concerned about.

[nowty]

I agree the factor one rule is probably a red herring, I think its more appropriate to countries insisting on Zero export and the time response of the inverter control which are not applicable here. But it may be something the DNO has misinterpreted in this case.

The point I'm trying to raise is that I have never heard before of the DNO limiting the number of panels of PV we have connected via a grid tie inverter. And for me this is a big deal, the repercussions are enormous if this became standard practice.

@sharpener has had such a limit imposed, so either, they don't understand how his system operates which I think and hope is the more likely reason.

[Andy]

Have you spoken to them directly. The teams are usually very helpful if you manage to engage them directly.

[sharpener]

I agree the factor one rule is probably a red herring, I think its more appropriate to countries insisting on Zero export and the time response of the inverter control which are not applicable here. But it may be something the DNO has misinterpreted in this case.

The point I'm trying to raise is that I have never heard before of the DNO limiting the number of panels of PV we have connected via a grid tie inverter. And for me this is a big deal, the repercussions are enormous if this became standard practice.

@sharpener has had such a limit imposed, so either, they don't understand how his system operates which I think and hope is the more likely reason.

Don't want to prolong this un-necessarily @nowty but which original post is the source of your concern?

They haven't restricted my AC-coupled PV, it was a pre-existing installation dating from 2011. They haven't restricted my DC-coupled PV because there isn't any as yet and I haven't raised the question yet (deliberately so).

I can live with the small limitation on inverter power, so at that point in the discussions (which were quite good-natured and in a problem-solving spirit) I considered the "best" might be the enemy of the "good" and decided to make an application that the DNO had indicated they would accept.

AIUI the primary purpose of the 1:1 rule is to prevent electrical damage caused by the PV power having nowhere to go esp. in a loss-of-grid situation. "At that moment the PV inverter will continue operating at full power until the AC frequency has been increased. Increasing this frequency will take a very short time, but during that time all power will be directed into the batteries as there is no other place for it to go."

[nowty]

Don't want to prolong this un-necessarily @nowty but which original post is the source of your concern?

They haven't restricted my AC-coupled PV, it was a pre-existing installation dating from 2011. They haven't restricted my DC-coupled PV because there isn't any as yet and I haven't raised the question yet (deliberately so).

Sorry I apologise, I must have mis-read a previous thread. I was under the impression in a previous thread that someone was restricted by a DNO about how many panels of PV they had on a grid tie inverter connected to some Victron system.

This I could not believe, so my sanity has been preserved by the fact you have not been PV panel restricted.

[sharpener]

No probs, you had me worried for a bit but I am glad we got it sorted!