jonstret avatar image
jonstret asked

UK G100 Issue 2 amendment 2 compliance for ESS

We have undertaken a number of Victron ESS installations in the UK. Each going through the fun of a G99 approval and often with G100 export controls.

For our systems installed up until May this year the G100 declaration was enough to satisfy the DNO. Since then we have been subject to witness testing - charged at up to £1100 per installation by the DNO.

Whilst the compliance officers from the DNO have been approving I am not sure that by the letter of the tests we should be passing. We have therefore taken the tough decision to not install any more victron systems until we can have an approved solution. (Which is a real shame as the ESS system is brilliant and our customers really really love the installs we have done)

I am keen to understand what other people are doing to satisfy the G100 requirements and how they are demonstrating compliance to the latest amendments.

I am also keen to understand Victrons plans to comply to the requirements that have been out since 2022.

I assume non-compliance is because it may be impossible to pass the tests or too expensive to rework the products.

Here are the standards and the test requirements - Its a long read but essential to comply to install the equipment legally in the UK (where there is an export limit which in our experience is nearly 100% of the time for a larger quattro system)

Thank you

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7 Answers
benlongcross avatar image
benlongcross answered ·

I have a similar issue - whilst it can be demonstrated that unit can manage an export limit i.e. setting the grid set point - the unit does not seem to go to a fail safe mode within 5 seconds if the CT plug is pulled or the meter USB pulled, which the DNO have asked to see.

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jonstret avatar image
jonstret answered ·

I agree that is a problem ( and which can be somewhat worked around with a justification that the Quattro has internal energy meter that takes over ). Also if you have a fronius solar inverter on ac out it will stop generating within 5 seconds of the energy meter being disconnected

There are other requirements that are more difficult to show such as cyber security or how the unit behaves after multiple resets.

It would be helpful for Victron to make some comment on their plans to comply or their recommendations to work around or acknowledge their system cannot be installed in the uk when there is an export limit demanded by the dno

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jonstret avatar image
jonstret answered ·

@mvader (Victron Energy)


It would be very helpful to know Victron plans in the uk

We love your products and so do our customers You clearly worked hard to get the g99 approvals through last year ( thank you ) but the 2022 g100 requirements are now making it nearly impossible to build a compliant solution with Victron ess

We would love to work with your team if that would be helpful.


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farmeroz avatar image
farmeroz answered ·

Just out of interest does this apply to multiplus 3000's.

These are incapable of exceeding the 3.68kW limit by design so as far as I can see do not need to meet G100.

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benlongcross avatar image benlongcross commented ·
If it is part of a wider system that has an export limit stipulated then could be an issue - for example, if it sits alongside say another 6kW AC coupled PV inverter - your system then has potential to generate 9kW and G100 may be applied to your system.
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jonstret avatar image
jonstret answered ·

You should double check ena regiater for your specific multiplus but most of the 3000 multiplus ii have g98 approval which is all you need. G100 Export limit May start from the 5000 unit and upwards pending your local grid infrastructure

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farmeroz avatar image farmeroz commented ·
As I read it g98 should be sufficient if the only grid-tied component is a single G98 approved device. Where are the regulations the G98 regulations are based on? Is it an act of parliament or just an arbitrary allowance with no legal standing other than contractual? Without sight of the legal position we are all (including the DNO's) just voicing some sort of opinion that is effectively unchallengeable.
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jonstret avatar image
jonstret answered ·

After a lot of research and calling to Victron installers I finally found one that understood the g100 problem and most importantly had a solution. Not only did have a solution for my Victron setup but when they went through the details with the dno they no longer needed witness testing. I am now all approved with 48/15000 quattro 8kw fronius inverter 2x1.8kw sunny boy inverters and a 450/100 mppt Total Generator for g99 is 23kw and g100 export limit of 8kw. All signed and sorted. Cost a few £k but worth it for the paperwork and comfort of a safe and compliant setup

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stefmari avatar image stefmari commented ·
Hi @jonstret

From you answer it looks like you have proven Victron's G100 to your DNO. Would be possible to detail the approach please? Entire community of Victron users can benefit. Looking forward.

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jonstret avatar image jonstret stefmari commented ·
Hi. I am not sure if the exact technical details but the team from off grid pro added another box before my meter. I believe this manages import and export and is the final line of defence should the grid set point fail and the inverter just dump all its power to the grid ( which we know it is never going to do )

They also had another option for me if I wanted to connect a backup generator and still maintain g99. ( which I may add later )

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Jason - UK avatar image Jason - UK stefmari commented ·

@stefmari most of the Victron products are now listed on the Type Test Register inc the MP II 5kva units. Because they are type test approved, its a basic witness of the commissining and all is good. Cost me a coupe hundred pounds to get my DNO application submitted and witnessed.


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stefmari avatar image
stefmari answered ·

Hi @Jason - UK Multiplus II were among the first ones certified against new revised G99 as you are showing. I am asking like many others about G100 Customer Limitation Scheme... for which I plan to put together 2 pag document where I plan to describe 'Grid Setpoint' feature of ESS. DNO is asking for details on Export Limitation ...


Anything to help answer to DNO's question on G100 would be appreciated.

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Jason - UK avatar image Jason - UK commented ·

@stefmari What they look for is a fail to safe interlock that actually prevent export over the allowed amount on top of a control that limits export in general. For example, a digital control that provides the general grid feed in limit like what is found within the Multiplus controls, plus another device that, if the export exceeds a set value, activates a relay, contractor or some other fail to safe interlock with in a set time period (I think its 0.8 of a second of exceeding the limit, or something like that).

A good example of a safety interlock on top of the Victron control is a CT sensor with built in relay set to your export limit, and that relay then interlocks with the Multiplus to stop the inverter. I had to supply a controls schematic with description as an addendum with my DNO application, plus a schematic of my mains distribution within my house and how the Multiplus and all other inverters are placed within my system, hence the reason it took me 9 months to retrospectively apply for my DNO application. I had to keep submitting additional info. My witness commissioning, I had to simulate the export exceeding the limit to provide the interlock. The CT sensor with built in relay would be located on the incoming tails, and they may also ask for a temper-proof tag on the CT sensor, photographed for their records so if they have to attend site, the can see of the interlock has been interfered with.

It sounds like a lot of work but actually its just a case of understanding what they want without them really giving you the detail of what they want. My temper tag just happened to be the same type of tags they used on the main fuses to indicated its been interfered with, the steel wire with lead seal type.
The schematic on my VRM portal in the photos section is a variation (some of the detail removed for security reasons) of what I issued them which they accepted.

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t-m avatar image t-m Jason - UK commented ·

Hi, Like @jonstret, I'm also very interested in how you have satisfied your DNO regarding G100 Issue 2 Amendment 2 compliance with a Multiplus II.

I'm investigating how to create a GivEnergy All-In-One clone (ac coupled ESS) using commodity components such as a Multiplus II and Fogstar/Seplos/Pylontech batteries. I eventually want this to work in conjunction with approx 6kW of Enphase Micro Inverters, so at this stage I also have to give serious consideration to what response I might get from my DNO when I apply to connect the ESS, and then later (next year) when I want to add the Solar PV and Enphase MI's.

So after looking at your photos, I have a couple of questions/observations which I hope you might answer.

1. Does the ET112 meter operate the 50A contactor alongside it in the same CU, and if so, which circuit does this operate, as it looks to be the circuit to the EV charger and not anything to do with preventing grid export for G100 purposes?

2. How does the "Grid Failure Interlock" work.

3. The schematic suggests there are two CT inputs to the MPII but the photo of the connections doesn't seem to show them both.

4. The CT clamp in the trunking does not contain an internal relay, but does have DIP switches to set its power level for visualising PV generation

5. The photo of the CT clamp shows the Blue/White&Blue going to one terminal, and the Orange/White&Orange going to the other terminal. To maintain the effectiveness of the twisted pairs you should really have put Blue/Orange together in one terminal, and White&Blue/Orange&Blue into the other terminal.


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jonstret avatar image jonstret Jason - UK commented ·
Jason. The solution I had supplied does exactly as you describe. The box I have watches the grid and acts as a second line of defence and triggers a contractor if the export goes over a set amount. My G100 limit was 17kw and I have a 48/15000 so there is no way I can export more than 12kw but they wanted it all the same. I also had to have witness testing and this was all fine and the SSE engineer was happy with the solution. We had to reduce the trigger point for the tests to prove it would work.

Energy saving days like today are great. I dump as fast as I can for 60 mins only on energy savings day

We love the whole Victron system

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t-m avatar image t-m jonstret commented ·

I know we've discussed this previously in a FB group, but does the contactor simply disconnect the MPII from the grid, or does it disconnect the loads from the MPII?

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stefmari avatar image stefmari t-m commented ·
This 'mystery' box can only connect a load to reduce the export (grid feed-in) and not disconnect loads.

Once energy is generated by PV cannot be destroyed but 'dumped' so...

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t-m avatar image t-m stefmari commented ·

If such a relay operates, it will surely be up to the designer of the system to ensure it fails safe. If the PV inverter is powered off, how is this any different to a grid failure during daytime?

This is from ENA EREC G100 Issue 2 Amendment 2, effective 01 May 2023


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