Not allowed a second home battery

So Northern Powergrid have denied my application to install a second powerwall, because they are worried about the potential export into the grid, and that it would raise the local voltage too much.

Any else had/heard of this and know if anything can be done about it?

However many power walls you have, the gateway limits battery discharge rates to 5.5kW. Add your PV kWp and that is your maximum possible export rate.

How does that compare with the rate quoted by the DNO? If it’s way out you could appeal.

I had not realised that, I had thought each Poawerwall2 could discharge 5kW, so 2 could discharge a maximum of 10kW. However, happy to stand corrected. Having said that, I did not think the Powerwall discharges to the grid. I’ve never seen mine do that in 2.5 years of operation.

I’ve currently put in application (G99 I think from memory) to replace a gateway 1 with a backup gateway and the DNO has rejected it as their policy does not allow island mode operation. Still in discussions so that may change.

Bad luck. My DNO is far more cooperative.

Hi Tim, each powerwall (2) had its own inverter and is capable of pushing 5kw out. The gateway just manages where the power is going. For some reason the DNO has decided that even though the powerwall does not output to the grid, this is software controlled so in the unlikely event that both powerwalls’ software malfunctions, and the gateway malfunctions AND the solar is generating at full capacity, then the substation could be at risk. (Or some nonsense). To me it just doesn’t add up and I’m looking for something to push back with really

Hi Oscar - out of interest where abouts are you? Thinking of doing something similar in Co Durham (also Northern Powergrid)…

North Yorkshire - Tadcaster Area. I think it is all down to what local system is in place

A single tesla powerwall is definitely certified G100 compliant. Are northern powergrid saying the chained system with 2 is not for g99 fast track or are they saying it is not compliant at all?

And do you have the new backup gateway 2?

Hi Ben, I have the gateway 2, and Northern Powergrid are saying that the G100 spec is not enough… even though there isn’t another spec as far as I know.
They say that with the extra inverter (in the powerwall) this is now too much potential output to the grid - even though the powerwalls don’t output.

I didn’t make the application myself, The phoenix works did this for me, so not sure on the specifics, however I believe the application was G99.

When I had the original solar+powerwall installed, this was done by Joju Solar. This was a G99, and included the 6kW inverter and the 5kW powerwall.
Surely an extra 5kW can’t make that much difference.

This does sound like rubbish. The backup gateway 2 is G100 compliant for controlling up to 10 powerwall 2. I have not heard any differently. It should be able to limit the export to the 16A required under G99 fast track (or whatever higher maximum export capacity you are allowed). If phoenix works did it Im sure they did it properly , the problem here is mis-application by northern power grid of the rules. What is the point of having equipment G100 certified if the DNO then just move the goal posts later? It might be worth getting in touch with Tesla UK directly to let them know about this. I will make separate enquiries about this. We went through all this stuff when batteries first came out so its annoying its all happening over again with the next generation of equipment.

Glad to hear that Ben, Phoenix works are still in talks with Northern Powergrid on this. I will keep chasing them up and see if they will let me talk to the engineer on Northern Powergrid’s side if they keep pushing it back.

I will contact Tesla in the meantime, let me know if you find anything. Very frustrating. I wonder if there is an ombudsman for DNOs…

You do have some recourse but like everything in this country it means opening your wallet. But I will speak to one of our grid connection partners about it who helped us with the batteries under the old regime.

thanks! in the meantime maybe i will start looking at heat batteries

Oscar - I suspect this is down to the actual connection in your area. Are you rural or urban. Any export will push up the voltage of the local line and as we only have single phase connections in the UK will cause a small imbalance between the phases.

NPG have to keep voltage within a specified range for all customers and this is much more difficult on rural networks which tend to be radial.

Not very rural, I live in a town. The issue I have is that the Gateway is supposed to deal with these issues, but Northern Powergrid aren’t accepting that and want me to install 3 phase… possible agenda here

Oscar - Yes they would be able to charge for this. There has been a recent change to connection charges in that DNOs now have to stand the cost of connections to support decarbonisation to domestic customers but I suspect this does not extend to multiphase connections. If they are willing to do it for free go for it - it will give you lots more options for the future. Ian

Wouldn’t be free, and also wouldn’t help me in this case either, as they would require the solar and batteries to be on different phases, therefore the batteries wouldn’t be charged from the solar, so rather pointless

I have had this issue with Western Power Distribution (who are normally a lot more helpful than Northern Power Grid in my experience). They said the issue is is that the system could export for a short period of time and push up local voltage. Powerwall systems are G100 approved, however, the G100 standard means that the unit will reduce export to zero in 5 seconds, not that it never exports. There concern was that 5.5kW export would increase voltage for up to 5 seconds.

1 Like

Sounds like they need a better spec then