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V2G costs from the DNO when fitting the charger - what and why?

  • 15 December 2019
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HI @Tim_OVO @Transparent

From the Social media page this seems to be worryingly cropping up multiple times on my page, is this an administration error from OVO? why should customers pay to become part of a trial, at a cost that looks like it could spiral to more than they would even achieve by join the trial ?> please see below I have removed the names, I have seen this multiple times from different interested parties. 

I hope you are well.

We have received an update from your Distribution Network Operator (DNO) with regards to applying to connect V2G units in your region. Unfortunately your DNO (Northern Powergrid) would charge you a design fee to further investigate the feasibility of your V2G connection. Typical design fees range from £260 + VAT for cases where the network supports full exports from the V2G unit with no additional works required to £350 + VAT for a connection solution where additional works are required. If additional works are required, it is likely that further fees will be charged by the DNO for a further technical study and the actual cost to carry out the enabling works. These further fees could range from a few hundred to a few thousand pounds. 

If you choose to proceed with the next stage of your application, we will pass your details to Northern Powergrid who will carry out this work and invoice you for these design fees directly. Please note, the design fees are payable even if the connection is not technically possible, or if you decide you do not wish to proceed further based on the cost of additional works required.

We have worked with DNOs around the UK to remove fees where possible to try and ensure our V2G trial has as low a cost of participation as possible. In this instance these costs are unfortunately outside of our control.

Please could you confirm if you wish to proceed with your application on the above basis by response to this email.

Kind regards,

OVO V2G Team
OVO Energy

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Best answer by Transparent 16 December 2019, 10:53

Hmmm… and a happy Monday morning to you too, @D10hul !

Before I get into the technical explanation of what’s going on, the way this issue gets resolved will depend on our attitude to the Kaluza V2G Trial.

The positive way forward is to regard “us” as part of a team which is developing and testing technology required for the future UK electricity grid. Thus we (us customers) and OVO/Kaluza are working together to address issues such as climate change.

As a commercial organisation, Kaluza must operate within the normal constraints of the energy sector, regulated by Ofgem.

As private citizens we have access to other routes, including writing to our MPs, the press and social media. We are just 11 months away from hosting the world’s next Climate Change conference, and these issues have cross-party support. So swift action is very much required and will be widely supported.

The alternative/negative view is that we get very annoyed with Kaluza, make wildly inaccurate statements to the press and stir up a backlash from DNOs such as Northern Powergrid. I don’t favour that strategy.

 

So let’s next explain the technical background:

Any power source which gets connected to the public electricity grid must have the appropriate certification. This confirms that it operates safely and within the supply limitations. For example if the grid fails, all power sources must detach themselves  in order avoid electrocuting engineers who need to work on the remedy!

There are three main levels of certification which affect us:

 

G98 (was G83) is applied to equipment which is pre-tested by the manufacturer and may not supply more than 16A /phase to the grid. In this category would be all those off-the-shelf solar PV inverters such as the Sunny Boy, Xantrex Solar etc.

G100 is a varient of G98 in that it has more than 4kW of connected generation, but will only provide 16A of that to the grid. This allows connection of east-west roofs with solar panels.

G99 (was G59) is for anything else. So you can design and build any type of electrical generator, but the testing and on-site commissioning must be done by an authorised company, which in almost all cases is the local DNO.

 

So I deduce that Indra/Kaluza have created the V2G charger and provided test results declaring it to be G98 compliant.

However, Northern Powergrid have looked into the matter and disagreed. Thus they now want the end-users to have on-site testing and commissioning of every unit as if it requires G99 certification.

That is their right, and they are obliged by Ofgem to ensure that they correctly assess all such scenarios, most especially as regards safety.

 

At this stage we don’t know why Northern Powergrid have reached such a conclusion so the next step must be to find out that reason. It could be:

  • the V2G charger is not self-contained and relies on external devices such as an rcd and current-detector to operate within the relevant G-standard.
  • they disagree with the test data supplied by Indra, and believe that the charger could place more than 16A onto the supply
  • they are not happy with the software control system of the Kaluza Platform, possibly because they’re not confident that it “fails safe” or that it couldn’t be hacked into by a 3rd party.
  • they are unhappy with the control system making charge/discharge decisions based on National Grid data rather than local factors within their own Distribution Grid

So the next step is for Triallists in Northern Powergrid’s territory to write to them and find out what their reasons are.

Please do this by email so that there is a written record with a time/date stamp to verify when it was sent. Such evidence may be needed later.

 

I actually believe that there should be a new G-standard for V2G and Storage batteries which permits them to supply far more than 16A /phase if the control software detects that this would be beneficial to local circumstances.

If my local sub-station was suffering losses due to phase-imbalances, a mere 16A is inadequate to redress the issue.

At the moment this is academic because the Kaluza-platform doesn’t receive data input from local substations at the moment. But it should do so at some future point.

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Hmmm… and a happy Monday morning to you too, @D10hul !

Before I get into the technical explanation of what’s going on, the way this issue gets resolved will depend on our attitude to the Kaluza V2G Trial.

The positive way forward is to regard “us” as part of a team which is developing and testing technology required for the future UK electricity grid. Thus we (us customers) and OVO/Kaluza are working together to address issues such as climate change.

As a commercial organisation, Kaluza must operate within the normal constraints of the energy sector, regulated by Ofgem.

As private citizens we have access to other routes, including writing to our MPs, the press and social media. We are just 11 months away from hosting the world’s next Climate Change conference, and these issues have cross-party support. So swift action is very much required and will be widely supported.

The alternative/negative view is that we get very annoyed with Kaluza, make wildly inaccurate statements to the press and stir up a backlash from DNOs such as Northern Powergrid. I don’t favour that strategy.

 

So let’s next explain the technical background:

Any power source which gets connected to the public electricity grid must have the appropriate certification. This confirms that it operates safely and within the supply limitations. For example if the grid fails, all power sources must detach themselves  in order avoid electrocuting engineers who need to work on the remedy!

There are three main levels of certification which affect us:

 

G98 (was G83) is applied to equipment which is pre-tested by the manufacturer and may not supply more than 16A /phase to the grid. In this category would be all those off-the-shelf solar PV inverters such as the Sunny Boy, Xantrex Solar etc.

G100 is a varient of G98 in that it has more than 4kW of connected generation, but will only provide 16A of that to the grid. This allows connection of east-west roofs with solar panels.

G99 (was G59) is for anything else. So you can design and build any type of electrical generator, but the testing and on-site commissioning must be done by an authorised company, which in almost all cases is the local DNO.

 

So I deduce that Indra/Kaluza have created the V2G charger and provided test results declaring it to be G98 compliant.

However, Northern Powergrid have looked into the matter and disagreed. Thus they now want the end-users to have on-site testing and commissioning of every unit as if it requires G99 certification.

That is their right, and they are obliged by Ofgem to ensure that they correctly assess all such scenarios, most especially as regards safety.

 

At this stage we don’t know why Northern Powergrid have reached such a conclusion so the next step must be to find out that reason. It could be:

  • the V2G charger is not self-contained and relies on external devices such as an rcd and current-detector to operate within the relevant G-standard.
  • they disagree with the test data supplied by Indra, and believe that the charger could place more than 16A onto the supply
  • they are not happy with the software control system of the Kaluza Platform, possibly because they’re not confident that it “fails safe” or that it couldn’t be hacked into by a 3rd party.
  • they are unhappy with the control system making charge/discharge decisions based on National Grid data rather than local factors within their own Distribution Grid

So the next step is for Triallists in Northern Powergrid’s territory to write to them and find out what their reasons are.

Please do this by email so that there is a written record with a time/date stamp to verify when it was sent. Such evidence may be needed later.

 

I actually believe that there should be a new G-standard for V2G and Storage batteries which permits them to supply far more than 16A /phase if the control software detects that this would be beneficial to local circumstances.

If my local sub-station was suffering losses due to phase-imbalances, a mere 16A is inadequate to redress the issue.

At the moment this is academic because the Kaluza-platform doesn’t receive data input from local substations at the moment. But it should do so at some future point.

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Thanks for posting, @D10hul - I’ll mark Transparent’s reply as the ‘best answer’ here - lots of context! From our point of view: 

 

These fees from the DNO are not ideal for those effected - which in itself is dependent on individual circumstances on site. It’s also not something we can promise to cover

 

There’s an ongoing effort from the industry to align the process with all DNOs, but in the meantime we can only be transparent, and give our members a chance to understand the fees in question and who is charging them, rather then automatically cancel the application. 

 

Is it realistic to hope for all DNOs to be aligned on this @vespalads @Kat Leaf @Leo Moran - ?

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@D10hul @Tim_OVO @Transparent …..

 

I suspect that the reason is probably more basic. I wasn’t charged by Northern Powergrid, at least I haven’t had the bill yet after 6 months. I had a site visit and then a couple of visits to install new equipment with nothing to pay….but mine was the first the engineer had done and I dare say that once they got quite a number of requests coming in then they want a slice of the Government Grant being supplied to OVO/ Kaluza and Nissan, can’t blame them really, after all without there help the whole trial  is a none starter…..just a thought.

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Interesting information @Leo Moran

I wasn’t aware that DNO Engineers had attended any V2G Charger installations. You wouldn’t expect a DNO to be present for domestic-level connections of products certified under G98.

Moreover, OVO/Kaluza also have a higher level of Approval to work on grid-connected equipment than most other Renewable Energy Installers. This comes about because they have engineers certificated to remove and re-seal Service Fuses as part of their Smart Meter work.

 

I sincerely hope that Northern Powergrid’s stance is not based on financial gain. If this transpires to be the case, then they’ll incur a slapped wrist from the Regulator, BEIS and MPs. That’s just the sort of issue which would hold up the Government’s strategy in the run-up to the Climate Change Conference in Nov’20.

Let’s wait and see what they say.

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@Transparent , The initial visit was from a site engineer from Northern Powergrid to check the site. The next was an engineer from Northern Powergrid to change the main fuse from 80 Amp to 100 Amp. An engineer from OVO Energy came to do the alterations to meter and replace the legs with higher rated cable and the two electricians from Kaluza came to do the V2G charger. One of them was qualified to work on the main fuse but the other wasn’t and only one was present the day it needed changing, hence the engineer from OVO…..I was surprised at just how much work was involved, certainly a lot of moving around. I wouldn’t care but I’d just had the cupboard cleaned up with all the wiring more neatly redone and put in a single box….and they came along and put more wires and more fuses/ switches in. Fortunately, just as neatly.

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hi I am looking at signing on to OVO v2g trial.  I am also in the Northern Powergrids region, so being asked to pay their design fees for participation, as outlined above  .  My local MP is Rishi Sunak MP, chief secretary to the treasury.  So I will ask both him and Northern Powergrids why consumers in the NE are being asked to fund these trials, 

 

Ofcourse government focus and Innovate UK funds are on the SE only as always!!!

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Hi @Dambrogio; Thanks for joining in with the debate.

Yes, I agree - Rishi Sunak MP looks like the best option. He’s got an MBA and has served on Environment Committee, so he has appropriate background.

Constituent’s letters to MPs are “privileged communication”. To retain this and allow him to investigate what’s going wrong and who’s responsible, I recommend that you do not post here any quotation from that correspondence (or release it to the press either). That doesn’t prevent you writing a separate letter to your local paper of course.

In this situation it is usual for the local MP to pass your correspondence on to the relevant Government Dept., requiring an answer from them. In this case it will be BEIS (Andrea Leadsom MP). So I usually try to write my letter/email in such a way that my MP can simply add a couple of comments before bouncing it on. Typically this might be something like

 - V2G is an important component part of HMG’s Climate Change initiatives; why are hurdles being placed in the way of some early adopters?

Remember also that you, OVO and Kaluza are on the same side here. It needs to be clear that you are questioning the decision of just one Distributed Network Operator (DNO) to treat its customers differently. If there really are safety concerns about this (type of) equipment, then you could suggest that BEIS release funds for an independent assessment of this and similar grid-connected storage technology.

Please refer to this Topic here on the OVO Forum. That allows a BEIS Civil Servant to follow what we’re discussing.

 

I have already spoken face-to-face with another Cabinet MP on this issue and the use of Smart Meters to provide grid balancing. If you need further background info to better inform Rishi Sunak MP, then please send me a Private Message.

 

Can I also point out that most Innovation Funding from Ofgem is being taken by Western Power Distribution, who have four Electricity Distribution Regions (but not the S.E.).

This is because WPD quickly agreed with Ofgem’s strategy for revenue-based efficiencies (known as RIIO), whereas others dug their heels in and two took legal action against Ofgem! That didn’t help their cause.

This is why Kaluza’s sub-station monitoring input was taken from a commercial trial-site at Crantock (North Cornwall) and their Home Storage Battery Trial is commencing in Lincoln. WPD is the DNO in each case.

 

@Tim_OVOcan you please message the relevant Kaluza Manager and let them follow what we’re discussing here? Thanks.

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Hello @D10hul @Transparent  @Leo Moran @Dambrogio 

 

I can confirm that we are working with all DNO’s to try and prevent charges where possible, currently we are aware of two DNOs which enforce connection and design fees. The two are NPG and SPEN. We are still in talks around removing fees for a fairer policy across the board and will keep our customers up to date with any progress. Essentially, each DNO is an independent company and they all operate within OFGEM regulation. However, they can have differing policies, and as such, the final decision is down to the DNO as to whether or not they charge.


As part of the V2G trial, we attempt to cover as much of the cost as realistically possible, but unfortunately DNO costs are considered out of scope.

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Hi Ash, thanks for the update.  I can confirm I have written to NPG and raised a complaint against their charges which act as a barrier to the V2G trial and take up of EVs in their region.  They rang me today and are investigating the issue.  So I should be able to provide their response at the end of the week.  It is good to know they are 1 of 2 DNOs that are blocking this trial, through the introduction of charges.

 

 

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Thanks @Ash_OVO. Clarifications appreciated.

There is an alternative approach which could be implemented in NPG and SPEN Distribution Regions.

As I understand it, Kaluza/Indra believe that the V2G Charger is tested and certified to G98 and can therefore be connected to the Grid without extra testing by the DNO.

However G98 (and G100) products limit grid export to 16A (per phase).

If we’re attempting to overcome supply problems in the Distribution Grid, then a mere 16A will make very little difference.

Below is a graph showing the current being drawn from a relatively lightly-loaded substation transformer over a period of five days:

 

On sunny days, such as Wednesday, there is significantly less current drawn from Phase-L2 than the other two phases. This imbalance causes losses in the substation and a corresponding rise in the core temperature.

Such substation losses have doubled since the Government introduced financial incentives to install solar arrays on domestic roofs. This is a serious problem and is unsustainable.

Either the excess generation on L2 needs directing to “loads” in houses connected to the same substation, or stored electricity needs to be released onto Phases L1 and L3.

A V2G charger left connected to an EV could fulfil either requirement. However, even on this substation, it will need to be able to deliver more than 16A unless there were several V2G chargers connected to the same substation.

 

If there are two DNOs who are in any case going to levy test and connection charges for certification under G99, then Kaluza might as well use this to their advantage to test the effects of delivering more than 16A per phase (as is permitted under G99).

I’m not suggesting that this is a long-term viable solution to nullify the losses caused by phase imbalance. But it does offer opportunities to glean data on whether such an approach is feasible. That, after all, is one of the aims of field-testing isn’t it?

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One other point I’d like to pickup from your response @Ash_OVO :

Whilst I agree that each DNO is a separate company, they are now required by Ofgem to change their modus operandi such that they become Distribution Service Organisations (DSOs) rather than the controlling body for Network Operations.

This is a significant change, such that they are now to be working in partnership with other companies and the community.

NPG will need to take care in their response to @Dambrogio lest they imply that they are not making this transition.

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Please find attached response from NPG .

Thank you for contacting Phil Jones, our Chief Executive, about the OVO Energy Vehicle-to-Grid trial and letting us know about your concerns, regarding our connection costs.

I am grateful for your patience while I have looked into this for you and I hope you find the following information useful.

I understand that you feel our design fees and potential follow-ups costs, are deterring customers from participating in this trial.

We are supportive of Vehicle-to-Grid as a concept and wish to see both this and other trials succeed. The battery capacity inherent in stationary electric vehicles will reach around a day and a half of GB electrical energy use by 2050. This represents a superb resource for the country, vastly reducing the need for fixed, grid connected energy storage. However, trials undertaken must follow legislation and regulatory guidance presently in place. 

It is possible that at some point in the future, perhaps as part of the electricity distribution price control review starting shortly, connection costs for low carbon technologies may be socialised. Ofgem, on our persuasion, moved towards this with Photovoltaic (PV) generation at RIIO-ED1, the network price control, but are yet to commit fully to this view.

Ofgem require us to be fair, to properly reflect costs and not to discriminate. The fees applicable for assessment and design arose from a change recently made to the legislation, by the Government with Ofgem’s support and guidance. The change in legislation was introduced in April 2018. We accept that it is possible that some DNO’s may not yet be following the spirit or letter of this legislation, though we have no further comment to make on this; however we have chosen to. The legislation is in customer’s interests, particularly those either connected to the system now or who are in the process of making a connection. This is because it protects them from the costs of speculative connection applications that never proceed, which was a significant problem prior to the legislation change.

There is also no generic safety issue with domestic generation or Vehicle-to-Grid installations; however, there is also a need to check that the local network is sufficient to support their use. A general dispensation for connections with a combined generation potential less than 16A per phase (3.68kW for most domestic premises), exists but otherwise all other connections are subject to a design and assessment check. This is to make sure that the system is not being overloaded or pushed outside voltage limits. Given that we understand there to be both PV generation and Vehicle-to-Grid at this property we understand the combined output to be 16A or more, hence the need to carry out the assessment and design. If we are wrong then that may change our requirements.

I realise that the information in this letter may not meet all of your expectations, however, I hope that I have helped you to understand our position. I am happy to send a hard copy in letter form if you require this.

I would like to thank you again for taking the time to contact us about this. If you do need any further help with this matter, please do not hesitate to contact me and I will be happy to assist.

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This response confuses me...All my three chargers are 32 Amp( I think, 6.6 kWh) and when the first two were fitted no checks were needed. However when the V2G was fitted they inspected the system and upped the main fuse from 80 Amps to 100 Amps. I can only suspect that the previous 2 installs weren’t referred to NPG. 

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Hi Leo,  are you in NPG region?  Did they charge you for the privilege of inspecting the fitting and upgrading the fuse to 100amps? 

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Hello @Dambrogio, Yes at Hartlepool and no they didn’t charge me. It was back in June or July when the charger was first installed (trial started 21st July). They did the inspection and then an engineer came out and replaced the main fuse….or rather he brought out the 100 Amp main fuse and left it for the OVE Engineer to fit it.

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@Leo Moran as you can see from my previous post, i have complained to NPG about them placing barriers to this V2G trial.  
 

looks like from your response they are in consistent in their response to V2G trial.  

anyone else had V2G installed in NPG area?

 

 

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looks like from your response they are in consistent in their response to V2G trial.  

anyone else had V2G installed in NPG area?

 

I’m bumping this to see if we can get a hit on other trialists in NPG areas ^

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Sorry for the delay @Dambrogio, but I really would like to feed back to the Forum regarding some of the statements in the letter you received from NPG on behalf of Phil Jones their CEO.

Firstly, NPG are to be commended for such a response. They have clearly listened to your complaint, are in no way dismissive, and have provided details of a number of background factors. All this bodes well.

Secondly, the letter states:

A general dispensation for connections with a combined generation potential less than 16A per phase (3.68kW for most domestic premises), exists but otherwise all other connections are subject to a design and assessment check.
and then

we understand there to be both PV generation and Vehicle-to-Grid at this property we understand the combined output to be 16A or more

and there’s the knub of the problem. G98 certification only holds good if you have one such installation at your house. According to NPG, you will have two ~ PV and V2G, each with separate inverters sensing the mains, and no software interlocks between them.

 

From a technical standpoint NPG are correct that this needs assessing. Apart from the obvious checks they can do to ensure that your substation has sufficient reverse capacity to receive such power, there are safety matters for them to consider.

All Grid-connected power sources must detect the incoming mains power to the house, and remove themselves from the Grid if the mains fails. If this were not so, then it has the potential to kill an engineer sent to service a substation, believing that the transformer is no longer “live”.

On re-establishment of mains power, domestic power-sources may still not revert to feed current back to the Grid. They must wait a randomised period of time (several minutes) before reconnection. If this were not so, then all such G98 devices in an area would reconnect simultaneously, causing a surge!

In your case you will have two such devices. So what happens if the PV Inverter first detects the drop in supply voltage?

The V2G Charger would now have a greater potential difference between its output stage (230v) and the mains (now falling below 230v) , so it could supply more current.

The PV Inverter then sees that the mains does not appear to have failed after all, so it too remains connected.

This should not happen, of course. But there exists the possibility that your two generation sources in close proximity would “tell” each other that the mains supply was healthy, and thus both remain connected. Independently they may be G98 certified, but together they could still fail to meet the criteria for that certification.

 

Now I do have some solutions to discuss!

But let me first give you and other V2G Trialists a chance to comment.

@D10hul@Leo Moran ?

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Dear All - escalated my complaint and today received a response from the head of policy development at NPGs.  A few things to note from his response.

  1. Comprehensive and NPG linked my complaint to my G99 application (which OVO appear to have wrongly submitted)
  2. Offering a solution of limiting exports to less than 16amps, which would require no assessment from their part
  3. Offered his mobile number and to talk to me directly ( i have removed his mobile number and name fro m my response below).

spoke to OVO today and at present they are unable to accept the limitation of exports to 16amps ( not sure why?)

 

And what would be the impact of this limitation on the payback for me on the V2G trail ?  (how often will exports exceed 16 amps?).  

 

 

 

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Here is  NPG response to me:

Thank you for contacting us about your intention to fit a vehicle to grid (V2G) charging unit, in addition to the solar panels you already have installed at your home.

Although I was disappointed to hear that you feel we have not provided you with a satisfactory outcome at level 1 of our complaints procedure, I have personally reviewed your complaint and I would like to thank you for your continued patience whilst this has taken place.

I write with my consideration of the responses we have already provided. I am also setting out the status of your application to date and the potential ways forward that are available for you.

I have checked the advice you have already been given by us, relating to the connection of your V2G charger. This includes the substantive response provided to you on 24 January 2020. The way that we have applied our policy for connection offer expenses is reasonable. Our policy for these essential design and assessment checks is based on a fair application of relevant legislation and it ensures that it is the customer requesting the service, that pays for the service. The charges reflect the cost of providing the design and assessment checks to accommodate a customer’s needs. To avoid subjective judgements, we base our charges on the type of connection that is being considered – in your case, the installation of export capability that exceeds the legally defined micro-generation limit of approximately 3.68kW.

As our previous response highlighted, we see V2G as a potential game changer that could unlock a significant volume of electrical energy storage. We expect this to benefit all customers by contributing to a smarter and more flexible energy system. The opportunities presented by electric vehicles, for users and our wider customer base, are a key component of our innovation programme. Accordingly, we are pre-disposed to support the Ovo Energy trial.

With the Ovo Energy trial, we have already responded to reduce barriers to participation for customers who are willing to accept a curtailment on their export capability. We were active in a recent industry technical standard group, to implement an interpretation of the standard that would allow customers with V2G (and no solar) to connect their units at no cost, if they use the charger set points to limit their export capability. 

Returning to your case of V2G in combination with solar, we note that Ovo Energy has triggered a connection request on your behalf. Ovo applied to us on 22 January 2020 and we provided a quote on 27 January 2020. This request indicated that a standard (uni-directional) 7kW charger was to be fitted. In line with our policies and standard practices, this type of connection only requires summary level assessment and therefore there are no associated costs in providing this quotation service. In our response to Ovo Energy we indicated that the existing connection is suitable for the charging unit to be fitted by a competent electrician, with no further reference to ourselves.

From our direct correspondence with you, we understand that a bi-directional V2G unit is the desired installation. As such, we are flagging to Ovo Energy that there is a need to confirm the requirement, so that we ensure we deliver for you what is needed.

If it is a V2G unit that is required, then there are two ways in which we could support your need. The first option is to provide you with an unconstrained generation or export capability, which exceeds the micro-generation limit. This means that you would need to pay for the assessment and design check to provide you with your quotation. Also, following that check, should any network upgrade be required then, dependent on the content of that work, you may need to pay for it. I realise this may be unacceptable to you, as it is the basis of your dissatisfaction.

An alternative second option is that you limit the generation export from your house (solar panels and V2G combined) to the approximate 3.68kW limit (specifically 16A per phase). In line with our policy, this would cause us to effectively consider your application as micro-generation, the costs of our design and quotation service would be socialised around all connections customers and if any work was required on the network then this would also be socialised and not paid for by you. Practically, you could achieve this by asking your V2G provider Ovo Energy to limit the export from your unit to 3.68kW using the settings in the unit. Further, you could also fit an export limiting device at the connection of your house to our network that would curtail your total solar generation and V2G output to stay within this limit.

In summary, I hope you will understand that the current technical thresholds for assessment of connections with generation export are in place for an important reason - i.e. to ensure the safe and secure operation of the local grid for all our customers. Likewise, our economic charging policies are set to deliver a fair and efficient development of the low carbon system. However, as demonstrated in the case of the Ovo Energy trial, we are always open to looking at how that policy is interpreted, as new technologies and solution become available. We seek to run an objective policy that is transparent and not open to subjective judgements on waivers. I consider that the options set out here for all trial participants to avoid any network costs by limiting their impact on the network, is an appropriate solution that both supports the trial and is fair for all our customers.

Please let us know how you wish to proceed and we can discuss what further details are required, depending on your chosen option.

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Wow… there’s a lot there to pour over.

May I first address the issue of the 16A export.

I think you imagine that the export current from your charger varies between 0-16A (max) according to demand. I don’t think that’s the case. It is more likely to be a digital on/off delivery back to the grid.

Compare the following, where the digital export is the blue graph on the right:

 

The way in which the Kaluza platform is presently making its decisions as to export is the national price per unit (kWh), rather than the amount of energy which is required in your local area.

The Kaluza software switches the export on/off with a granularity of 1 minute.

Although this isn’t explained or displayed in any great technical detail, you can see the import/export graphs on a slide in the Webinar referred to here on this V2G Discussion Topic. The slide I’m referring to appears at 12m 32s.

If this is so, then there is no mechanism by which the V2G Charger can be controlled such that the sum of your PV export and V2G export is no greater than 16A.

To do that you would require two inputs to a single grid-connected inverter designed to operate under the G100 standard.

Both your PV inverter and the V2G charger are designed as independent G98 devices.

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OK @Dambrogio may I now put forward a solution which would probably satisfy the concerns raised by NPG. However there a number of reasons why Indra/Kaluza may not favour it.

I’m still picking up the same point made in the reply you received from their Head of Development Policy:

An… option is that you limit the generation export from your house (solar panels and V2G combined) to the approximate 3.68kW limit.

This diagram shows a basic method of achieving that:

 

 

The V2G charger has a control line added which switches a relay. Only one of your sources is therefore connected to the mains electricity at a time.

So what are the limitations of this approach?

  • You are unable to export any solar PV output whilst the EV is charging or discharging. This may not be a problem in the early evening (export) or middle of the night (charging).
  • You cannot use any of your own solar to charge the EV.
  • The V2G charger needs modifying to have an extra control line. Both it and the accompanying relay will need re-certifying to G98.
  • When your PV Inverter loses its mains connection, it immediately shuts down. When it “sees” the mains 50Hz again, it waits a random period of time (typically several minutes)  before it starts exporting.

NB I have deliberately over-simplified the above diagram, omitting safety isolator switches and connectors.

 

@Transparent thanks. I did ask about the possibility of getting a switch installed like the ones used to switch between 7kW charger and V2G, but they weren’t keen and thought it would be better to wait for the G100. 

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Is that an “announcement”, @Brie ?

Has Indra decided to change the design to a G100 certification, whereby the V2G charger also controls the PV-panel export?

That may resolve the present problem that Kaluza is presently facing with a couple of DNOs.

However, there is actually a need to have some controllable grid-export rated higher than 16A/phase. This is needed to help resolve a different issue where there is significant imbalance between the current being drawn from a sub-station transformer across the 3-phases.

Here’s a typical graph from a substation in West Devon at the end of March 2019. The current being drawn from the grid by houses on the yellow phase is less than the other two. The difference is greatest in daytime, suggesting that this is exacerbated by those houses also having a higher %age of PV solar generation.

Phase imbalances like this have increased losses on the distribution-grid from around 5% to 10% over the past 20 years. That is unsustainable.

To redress the phase-imbalance will require grid-controlled devices capable of import and export at currents greater than 16A. I think we need a new G-standard, capable of achieving higher-current export where sub-station monitoring is deployed.

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