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Powerwall 2 update

Dilly

Active Member
Feb 24, 2020
2,867
2,306
Norfolk
As an aside, those of us who have Powerwall 2’s appear to have a major update coming. I presume US first and filter through later.
both capacity and output should see an increase which will be welcome to those capped at 3.5Kwh
there is an artice on Electreck reporting it.
 
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Dilly

Active Member
Feb 24, 2020
2,867
2,306
Norfolk
Is the implication that those of us with a 3.5kW power output restrictions (due to DNO limitations) will see that raised? Additional capacity would be welcome.
I’m not wholly sure why a restriction exists. My first one was capped but when the second was installed both were uncapped with ease and I can now draw 10kwh from them plus a further potential 10.9Kwh from my panels. In theory the DNO should not be concerned by output as it’s purely internal though the ability to draw more from the grid would be of interest. The proposed change could allow peaks of 14Kwh.discharge and perhaps charge.
capacity increase seems reliant on higher air temperature.
 
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KennethS

Member
Supporting Member
May 3, 2019
662
477
Herts, UK
If I understand correctly, my DNO has put a limit on how much juice I can dump into the grid, but there is no DNO restriction on the amount that can be fed into my consumer unit for our home's need. The existing limit of 5Kw from the Powerwall has never really been an issue in our home, although it is insufficient on its own when charging the car. Any boost in the potential of the Powerwall is always welcome, and any increase in its storage capacity would be most welcome but I had not read that was changing whenever the new discharge rate limit gets rolled out.
I’m not wholly sure why a restriction exists. My first one was capped but when the second was installed both were uncapped with ease and I can now draw 10kwh from them plus a further potential 10.9Kwh from my panels. In theory the DNO should not be concerned by output as it’s purely internal though the ability to draw more from the grid would be of interest. The proposed change could allow peaks of 14Kwh.discharge and perhaps charge.
capacity increase seems reliant on higher air temperature.
 
My understanding of it from speaking with our installer is that the DNO limit (3.7kW in our case) is also applied to the powerwall, so it is artificially capped to that rate. I wonder if it is in case the powerwall pushes power to the grid occasionally? It does seem odd if it only ever supplies it to the house.
 

Dilly

Active Member
Feb 24, 2020
2,867
2,306
Norfolk
My understanding of it from speaking with our installer is that the DNO limit (3.7kW in our case) is also applied to the powerwall, so it is artificially capped to that rate. I wonder if it is in case the powerwall pushes power to the grid occasionally? It does seem odd if it only ever supplies it to the house.
That’s the odd thing. PW is designed not to export by default though it does have the capability. Mine will push a couple of hundred watts now and again, generally less, but only because it’s balancing with the grid.
 
Regarding the 3.6kW limit imposed by the DNO, it exists as a rule because when the grid connection goes down, inverters etc do not off instantaneously. To limit the extent to which power is briefly pushed in this scenario, they can impose a limit on output. In our case, we already have two times 4.0kW solar inverters, which was as much export as they would allow. We asked about a Powerwall 2, and we can have this as long as there is no export, and its output is limited to 3.6kW. We haven't gone ahead with it yet.

Edit: I don't think this update will increase output for those with a 3.6kW output limit. That's a hard limit imposed by the DNO.
 
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KennethS

Member
Supporting Member
May 3, 2019
662
477
Herts, UK
That’s the odd thing. PW is designed not to export by default though it does have the capability. Mine will push a couple of hundred watts now and again, generally less, but only because it’s balancing with the grid.
Perhaps because I’m on the Octopus Tesla Energy Plan, but my Powerwall definitely does export to the grid. My DNO has limited me to 3.7Kw on the export but the battery will push out up to 5Kw during peak times and runs the house while dumping 3.7Kw to the grid.
 

Dilly

Active Member
Feb 24, 2020
2,867
2,306
Norfolk
Regarding the 3.6kW limit imposed by the DNO, it exists as a rule because when the grid connection goes down, inverters etc do not off instantaneously. To limit the extent to which power is briefly pushed in this scenario, they can impose a limit on output. In our case, we already have two times 4.0kW solar inverters, which was as much export as they would allow. We asked about a Powerwall 2, and we can have this as long as there is no export, and its output is limited to 3.6kW. We haven't gone ahead with it yet.

Edit: I don't think this update will increase output for those with a 3.6kW output limit. That's a hard limit imposed by the DNO.
With Gateway 2, solar inverters don’t power down at all (Unless they are exporting, in which case they just reduce output) If the grid fails, it isolates and carries on virtually unnoticed.
 
With Backup gateway 2, there is a site export limit which is set to whatever the DNO has said you can have. This is separate from whatever capacity limit your powerwall(s) have.

3.6 (per phase I think) kW is the max export you can do and the only requirement is to notifying the DNO after the fact. You can ask for much larger values, the bigger the value the more extensive the paperwork is and the greater the chance the DNO might decide reinforcement works might be required (that you might have to contribute to).

I have a 6kW export allowance which didn't cost me anything - I just had to wait 7-8 weeks for the DNO to approve it. (Incidentally when I spoke to them they said they don't actually care about battery storage as long as you stuck to the limit and all the things you were connected were type approved (ie you're a consumer installing off the shelf kit from a manufacturer that has had testing performed))
 
3.6 (per phase I think) kW is the max export you can do and the only requirement is to notifying the DNO after the fact.

The conversation that I had with my DNO last year was that the limit of 16A (nominal approx 3.6kW) per phase for retrospective approval includes all micro generation sources, including solar and battery. So if you have solar and want to install another form of micro generation such as battery storage even if no plans to export from storage you still need to get approval prior to installation. If your one and only install is 16A or less and your new install is 16A or less, then you can go a fast track route, but you still need prior approval from the DNO to show that its compliant and notify them when commissioned. I got the impression that even if there was no intention to export from battery, ie battery storage prevented export, then the DNO would still grant an export limit for the storage - which may have a use if it was then decided to financially benefit from further grid export.
 

Dilly

Active Member
Feb 24, 2020
2,867
2,306
Norfolk
With Backup gateway 2, there is a site export limit which is set to whatever the DNO has said you can have. This is separate from whatever capacity limit your powerwall(s) have.

3.6 (per phase I think) kW is the max export you can do and the only requirement is to notifying the DNO after the fact. You can ask for much larger values, the bigger the value the more extensive the paperwork is and the greater the chance the DNO might decide reinforcement works might be required (that you might have to contribute to).

I have a 6kW export allowance which didn't cost me anything - I just had to wait 7-8 weeks for the DNO to approve it. (Incidentally when I spoke to them they said they don't actually care about battery storage as long as you stuck to the limit and all the things you were connected were type approved (ie you're a consumer installing off the shelf kit from a manufacturer that has had testing performed))
Yes. In essence, DNO aren’t concerned by Powerwalls because they don’t export (unless by separate agreement). My limit is 7Kw for my primary panels which were installed in 2015. My secondary panels can’t export. I have a 100amp supply. Internally, I can draw 20Kwh without using the grid, being the total available from panels and batteries.
 

Dilly

Active Member
Feb 24, 2020
2,867
2,306
Norfolk
My understanding from Elon’s tweet was that power would increase potentially by more than 50%
I don’t think he made any suggestion that capacity would be increased as well? Surely increasing capacity would mean “eating into” the buffers, and I personally would rather keep the 13.5kWh and have a Powerwall that lasts 20 years.
It was dependant upon environment temperature and I think 30°C was mentioned. If true, capacity will increase for one week a year 🤣
 

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