question

@mfred68 short answer is no if you are in the UK you have to notify your DNO of a generator type connection, that also covers battery storage.

There is a huge demand on the grid they have to make sure that it’s not going to overload there transformers especially if you then add EV Heatpump into the mix and to check the design of the system. The day and age we live in where you can get inverters and the like from everywhere they make sure it’s compatible.

Cant speak for all DNO’s regarding pricing of G99 but I done it on my own with the help from forum members and (UK Power Networks) me nothing for this.

If there ever is a fault that requires the grid at your address it might be hard convo if they pick it up. The only off grid is no grid connection you are charging from the grid so you are connected to the grid so it’s not going to be off grid.

You can run the MultiPlus-II in "Generator mode" and simply put a contactor with a timer on it.

Then you will NEVER feed-In and your Batteries are charged only in the specific time.

This will AFAIK not require an authorisation.

@mfred68 If you set the grid code to 'not allowed to feed DC in', then yes. Much the same as with mobile and off-grid installations. ESS cannot be used and scheduled charging won't be available. In simple terms, the inverter won't run when there is an active grid connection and only run when the grid is disconnected. Be mindful that this way you can overload the system as it won't use AC for shortfalls as with ESS, but can be configured with AC ignore to completely switch over to AC (passthru) when certain conditions occur. Could prove more problematic with some appliances e.g. ovens that switch in and out. As for demand management, it is primarily for the grid synchronised feed-in aspect given properties have a cutout rating of typically 100A in newer properties which the DNO should already be able to supply regardless of the type of load e.g. your 32A plasma cutters, hottubs etc. that the are blissfully unaware of :) First image shows AC ignore and second ESS which requires DNO applications/notifications.

AFAIK There is no requirement to tell your DNO about ANY appliances that consume electricity being installed.

They only require notification if you are feeding back into the grid.

As @sharpener i believe they should be notified and I would say prior to connection as the potential power is over 3.6kW meaning DNO notified prior to connection to the grid rather than the notification after connection that any potential power connection of 3.6kW or below allows as for shore/grid I don’t know if they have mechanisms in place as fail safes or allowances I’m only commenting on the domestic home side of it, but it doesn’t matter what I believe as it needs to be official from the horses mouth so to speak.

I have emailed my supplier UK Power Networks for a formal response around this area (No Posts have been linked just me asking questions for a formal response) yes I know there are many DNO’s in different regions but I imagine this will be all DNO’s that would adhere to this.

This is why I have asked for a formal response and imagine it would have to go through a few channels before an official response so I imagine really slow. Saying that they have been really fast every other time I had to contact them.

@ejrossouw yes OP should, but as OP requested help from a public forum which all have access to and may take comments as a definitive answer IMHO it can only definitely come from a definitive source.

“I can give examples of members in this forum with the same DNO where one is requested to limit output of a system to less than 3.68kW while another with the same DNO obtains approval for a parallel 5kVA installation and 4.4kW export”

On examples you outline the DNO was contacted to one impose a limit and second to approve without a limit. In both examples the DNO would have been notified in order that the recipients receive the above approval conditions.

Either way this lands I’ll put the full email minus my details and this will hopefully be definitive as I’ve asked for definitive answers not just what they have on there website.

I agree that you should request permission of the DNO.

there may be ways to disconnect entirely, working around the need. But easier (IMHO) just to request, and reserve that evasive action for if they (unlikely) refuse.

FWIW, I just requested to connect a MP-II GX/5k, and saw no problems nor even queries.

The 5k version is request and approve, but it is possible that the 3k version is notify-only due to being below the power below the threshold requiring it to be request.

Call up your DNO and ask for their guidance on what form to fill and so on.

[moderator note: edited slightly to differentiate user statement from quoted DNO statement]

As promised a response from a DNO ( UK Power Networks ) in short yes you have to tell them, they also go into detail of the occasions when you don’t:

"Good morning,

Thanks for your email.

Any device being installed, even if the export is set to 0kW, must be registered as compliant on the ENA database so that they automatically shut off any potential export to the grid when there is a power outage (manual shut off will not be compliant).

If you are installing a battery to the DC side of an existing system and inverter, then you do not need to notify us as there is no change to the export that is already approved by the DNO. If the existing system does not already have an approval, then you will need to make the relevant application depending on the total export.

If there is no existing system / inverter and you are only installing a battery, then you will still need to notify us even if you are setting the battery to 0kW Export as the inverter for the battery will have the capability of exporting.

If the inverter for the battery does not exceed 3.68kW (the max. export capabilities will never exceed 3.68kW even if you set it to 0kW Export) then you will need to submit a G-98 Notification along with a SLD Schematic which can be done after installation. This will need to state the Export limit; if this is set to 0kW then you will need to accompany the application with a G-100 Declaration confirming the inverter will never export to the grid.

If the inverter for the battery exceeds 3.68kW, for example a 4 or 5kW inverter etc., then you will need to submit a G-99 application and SLD Schematic prior to the installation. As above this will need to be accompanied by a G-100 declaration if the Export will be limited to 0kW.

All forms can be found on the ENA website.

Regarding what we class as import when the battery is charging and if your supply is sufficient for the additional load, this will have to be investigated by an electrician who will calculate your usage including the device to be installed; we only assess the export onto the grid (any change in import will have to be discussed with an electrician and if your supply or main cut out fuse requires upgrading then you will need to come to us before hand)."

Kind Regards

In short - yes, as soon as you've gone into ESS mode with the MP-II - I've just gome from total off grid to using ESS. The DNO (they came round last year to provide us a TNCS earthing system / fuse upgrade) have been very helpful so far, in that I've got 2-3 months to commision our system, and ourselves to provide a SLD etc. will advise as to whether we get full approval.