Not allowed a second home battery

Home Retrofit
21

@paul_chandler - where did you get to with this please?

I’m having a very similar issue - York/Selby area, also NPG, trying to get Solar + battery (1 or 2 PW) installed.

My G99 application was for 8kW Solar Edge inverter + 1x Powerwall at 5kW. After about 9weeks of waiting they’ve come back basically prohibiting any viable form of AC battery by saying it takes too long to fail safe.

I have now had chance to carry out a voltage assessment. The connection of 13kW generation cannot be connected on the current arrangement and would require physical works to allow the connection.

I appreciate the Tesla Gateway can be export limited however this can take up to 5 seconds to operate, as such we will only allow a maximum voltage rise 1% above statutory limits (10%/253V) in this time period, which is 11% in total (255.3V). We can only allow a maximum amount of installed generation (solar and battery combined) of 9kW, with export limitation set to export no more than 6kW to the grid.

I have placed your application on stop as you may wish to change your requirements to within the maximums stated. There are cost implications to proceeding with the amount of generation previously requested. You will need to pay the connection offer expense of £660 plus VAT and also for any works required to bring the voltage rise on the network down to within statutory limits prior to being able to connect.

If you wish to change your requirements, please let me know and submit new documentation for the new equipment and a new single line diagram of the installation.

They are allowing a system of up to 9kW install, but only 6kW export. If you take the PW as the initial 5kW, even when limited to zero export, that leaves 1kW of solar headroom! Or I go 9kW solar with DC battery, but then I lose my whole house back-up…

they claim:

I appreciate the Tesla Gateway can be export limited however this can take up to 5 seconds to operate, as such we will only allow a maximum voltage rise 1% above statutory limits (10%/253V) in this time period, which is 11% in total (255.3V). We can only allow a maximum amount of installed generation (solar and battery combined) of 9kW, with export limitation set to export no more than 6kW to the grid.

To improve this they’ve kindly offered:
We would need to extend a main from the end of the street to within a 20m service length to the property. This is approximately 100m of mains cable in footpath and 20m of service cable, 12m in footpath the rest within the property boundary. We would also need to transfer the property on to phase L1 as there is already numerous houses connected on L2 with generation (this is the phase in which the property is currently connected to).
You would be looking at a cost of around £16,500 plus VAT for this work. This would allow for the connection at 13kW, however you would need to limit your export to 10kW.

They’ve got me over a barrel!

22

@Oscar_Scott - how about you, did you get anywhere?

23

Unfortunately no, I ended up moving (for other reasons).
Incidentally, at my new property, also under Northern Powergrid, there is no issue at all, but it is on a new build site, with a brand new (tier 2) transformer in the substation.

I think the main issue here is my old property, and probably yours is connected to an older transformer that cannot handle the changes in power as well.
Coupled to the fact that the tesla powerwall can now output to the grid on command, I imagine this is going to be even more difficult to put past NPG.

Old infrastructure needs to be upgraded, and in your case it seems that they want to put you on a separate phase. Something that will need doing at one point, but they are trying to get you to pay for the privilege of doing it right now

1 Like
24

Thank you for replying 2 yrs later!

Yes, it seems our initiative is being penalised and it’s really their problem at a fundamental infrastructure level.

I don’t think this will go in my favour, so I need to find an alternative ‘whole-house’ back-up option as that’s something I’m not willing to compromise on.

There’s no point moving right now, just for this, what with mortgage rates up and house prices a bit volatile.

25

Not having a choice of phases at your nearest access point (under the pavement outside your house or nearest pole in rural areas) tells you that the local grid is not fit for purpose. Properties on a new development alternate the phases to spread the load between them.

If you wait there is a chance that you and your neighbours can first request a grid upgrade for your street. The DNO will refuse without serious consideration and then it need to be taken up with Ofgem.

26

Sadly we’re not keen on new housing developments, they’ve boring and the gardens are often tiny! But I appreciate the underlying infrastructure is better…

I’m pursuing the G99 SGI-3 process at present - basically trying to say that a PowerWall, set to zero export, is G100 compliant. I’m not sure how it can affect the voltage if we had a grid outage, as there’s no grid (so no voltage).

27

I didn’t intend to suggest that you move to a new development. I was simply comparing the electricity supply situation with yours. I too would steer clear of a new development, unless perhaps it was one of the very few Passivhaus ones.