DNO Refused Tesla Powerwall - any advice ?

Screwdriva

https://forums.moneysavingexpert.com/discussion/comment/81961362#Comment_81961362

Sadly, this may just be somewhat accurate. And yes, Tesla did provide training which did lead to early wins but things are different in a world where solar adoption is becoming widespread. Without large scale grid modernization, we will soon live in a world where 5-6kWh export allowances will be the best case outcome.

To highlight this, UK Power Networks recently suspended the automatic 5kWh export allowance for several cities they service. It's now back to 3.68kWh :(

In my experience, current DNO export outcomes can vary by installer. Those willing to invest the time to fight can get better results 25-50% of the time (I track these in a spreadsheet for everyone I help). They do profit slightly (~£25 per panel) from increased panel count but this does not come close to the investment needed to successfully increase export kWh amounts, per property.

tiya1990

OP here - sorry for the delay in replying .

The DNO has clarified that the maximum we can install is 12KW and we are limited to G100 export of 5KW.

I am not hugely bothered about the export cap currently given our consumption but have a few queries :

1. @MattMattMattUK Does our installer now have to apply for G100 so that we can use the whole battery capacity for storage but export is capped at 5KW ?

Reparation work is 8K + another 17K for 'potential third party disputes' - as per their estimate - so we will not be going there .

2. @Martyn1981 suggested replacing the current 6KW inverter with the PW3 which sounds sensible . So we only have to deal with one App etc. Is this technically possible ?

3. @NedS - The 5+5 scheme has not been suggested to me . Maybe I will ask our DNO .

4. @Screwdriva - I will speak to our installers so that export is limited to 5KW but we can use the full 11.5KW battery for our own usage.

I would like to ask a very basic question - say if we decide in a few years time to upgrade to more storage - and NG permits it - is it a simple upgrade to say the full 18KW potential or will that be very complicated even if the Grid can take it ?

Thank You for your time and the helpful suggestions so far

Screwdriva

https://forums.moneysavingexpert.com/discussion/comment/81963776#Comment_81963776

I have never heard of a DNO limiting battery storage. On rare occasions they try to limit generation but this is easily appealed and overturned as long as export is limited as per G99 process. As expected, they have limited only export to 5kWh in your case.

You can add as many expansion packs as you would like - the DNO has no way of restricting this. That said, I would monitor your usage patterns first and take a call in a couple months before the rebate expires.

I always encourage all export restricted(<6 kWh) PW3 owners to reapply for higher G99 every 2-3 years. If successful, the Powerwall 3 is one of the only battery inverters that can have its inverter reprogrammed to support 6 -11kWh export allowances with zero hardware changes. This is yet another advantage of this system's future proof design.

tiya1990

@Screwdriva - that's a very helpful suggestion regarding the PW3 . I was wondering if it is worth spending that much more on the PW3 if we are so limited by the DNO but your logic is sound and has convinced me that the extra cost is worth it.

tiya1990

I have just had a look at the DNO's email and she has capped the install at 12KW .

So does that mean that we can't have the PW3 at all ? as our current inverter is 6KW …..

QrizB

Unless there's something really special about your current inverter, I wouldn't bother keeping it. Replace it with the Powerwall and you'll avoid a set of DC-to-AC-to-DC conversion losses when charging the PW3 from solar.