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Discussion: "Powerwall +"
- Thread starter willow_hiller
- Start date
SilverSp33d3r
No Longer Silver
Technically they cannot deny this. As a homeowner you are required to provide a meter socket rated for your service panel, the utilities do not dictate which are acceptable. Glad we have a live install that shows the meter socket adapter being used.
I don't believe that's true. POCOs have lots of requirements that exceed the NEC, so they disallow lots of otherwise compliant things for an electrical service. A simple example would be a minimum underground service conduit size that exceeds the minimum size the NEC would allow for the conductors that are going to be in it. They have the power to enforce these requirements, because if you don't comply, they won't hook up your power.
Unless you're aware of a PUC ruling that says the POCOs have to allow certain types of meter adapters?
Cheers, Wayne
SilverSp33d3r
No Longer Silver
Most utilities have meter socket requirements. As long as that meter socket meets those requirements the remainder is not relevant. No I do not have puc documents however I do work for a large utility company here in California whom conducts business in both gas and electricity 
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preilly44
Member
We have 800amp service going in our new construction house and I just requested our (hopefully) soon to be installed 35kw solar/4PW system be changed to PW+ so we can backup the entire house instead of just one 200amp panel. Does anyone know if PW+ will work with 800amp (or even 600amp) service for whole home backup? I don't really know how it backups up the entire house so I'm curious if anyone has any insight.
Thanks!
Thanks!
You have two issues:
- The Powerwall+ is limited to a 7.5kW solar system.
- The Powerwall+ meter adapter is limited to 200A just like the Backup Gateway 2.
It seems like it's possible to combine multiple PW+. Here's one example of a 12.24 kW system being quoted two PW+ and one PW2:
I guess that makes sense. But for his 35kW system he would need 5 Powerwall+ systems, where he was only looking for 4 Powerwalls.
Actually I think that would work pretty well. 4 PW+ should be 30.4 kW AC, which would yield an AC/DC ratio of 1.15. With a system that large, I imagine there are probably a lot of different roof surfaces covered, so the odds of any clipping would be really low.
The transfer switch (gateway) is only 200A. If your 800A service can be split into separate 200A panels, then you might be able to divide the critical and non-backed up loads and put separate PW(+) on as many panels as needed.
Is this the same / similar thing from San Diego Gas & Electric "Renewable Meter Adapter" ? Renewable Meter Adapter | San Diego Gas & Electric
That has the current flowing in/out the side cable. The speculation is the Tesla adapter does NOT carry any current out the side, instead it "simply" is a relay and likely sensors to detect the amount of current flowing. Basically a disconnect switch. The photo that has been shared that shows the cable going to the Tesla adapter seems to confirm the speculation. So in short, no.
Pages 14-15 here have some interesting details. https://tesla-cdn.thron.com/static/...name="powerwall-2-ac-owners-manual-en-na.pdf"
I think there is a third issue. Each powerwall is 30 amps. Four would be 120, obviously.
I don't know what you have going on with 800 amps, but there is no way four PWs could handle all of it. Now, if the 800 is because of something like its actually four separate structures/houses of 200 each that would be one thing, or a house of 200 and a pool with waterfall of 200.
Perhaps one of the more technically gifted posters could chime in but this is the same issue people who only want one powerwall to back up the entire house to simply make it through peak time may run into.
preilly44
Member
I spoke to a Tesla Advisor (not mine but some random guy) who said that the last he they were only doing PW+ for systems up to 12kw because they just started deploying it and are ramping up in size slowly. I don't know how accurate that is but I guess I'll find out in a week or two when they come back with the updated design (if they can).
Just more info on my setup, we have 4 200 amp panels, 3 of which are for the main house and 1 for the guest house/pool area. I'd prefer to have more than one 200 amp panel backed up but I don't only want one PW+ per panel...that doesn't seem like it would be enough power. I'm willing to go up to 5 PW+ if that helps things but I doubt it will matter based on what you guys are saying.
Thanks for all the info you all have provided!
Just more info on my setup, we have 4 200 amp panels, 3 of which are for the main house and 1 for the guest house/pool area. I'd prefer to have more than one 200 amp panel backed up but I don't only want one PW+ per panel...that doesn't seem like it would be enough power. I'm willing to go up to 5 PW+ if that helps things but I doubt it will matter based on what you guys are saying.
Thanks for all the info you all have provided!
Looks like the California PUC had a presentation (pptx) last year about Tesla's Backup Switch:
And comparison with Backup Switch for whole house backup vs without and partial backup:
And comparison with Backup Switch for whole house backup vs without and partial backup:
Interesting - so they are only using the meter socket adapter to act as the disconnect when the grid goes away.
Initially I proposed that they would use a meter socket adapter to provide both a disconnect and perform the equivalent of a line-side-tap as is done with other "Renewable Meter Adapters". Existing Powerwall 2s to get 50% power capacity increase with SW update...
This is simpler - and there must be a reason why they explicitly state that this is not a line side tap. Harder to get approval?
The main downside of this not being a line-side tap is that on 100-125A panels which are pretty common, this will not let you backfeed more than 20% of the main panel's busbar rating, unless it also has some secret-sauce that monitors current on both the main feed and the solar/battery feed at the same time to avoid overloading the main panel.
Initially I proposed that they would use a meter socket adapter to provide both a disconnect and perform the equivalent of a line-side-tap as is done with other "Renewable Meter Adapters". Existing Powerwall 2s to get 50% power capacity increase with SW update...
This is simpler - and there must be a reason why they explicitly state that this is not a line side tap. Harder to get approval?
The main downside of this not being a line-side tap is that on 100-125A panels which are pretty common, this will not let you backfeed more than 20% of the main panel's busbar rating, unless it also has some secret-sauce that monitors current on both the main feed and the solar/battery feed at the same time to avoid overloading the main panel.
The way it was explained to me.
First, it doesn't take an electrician to realize that a standard panel for a home contains more amps "in breakers" than the actual amps feeding the panel. That's because, I guess, no one figures all the breakers will be at max.
Anyway, since I got 3 PWs I really wanted to know if the three (90 amps) would work, or whether I should get 4.
My electrician, who is a nice guy but definitely on the spectrum, said, "OK, lets test it."
He came out with some sort of guage and we turned on every electrical load in the house, AC, every light, every flat panel, every computer, left all the doors open on two refridgerators and two wine coolers, ---- you get the picture.
He said "you're going to draw about 70 amps."
I said, how do you know that? He said, "unless you have a pool pump, three koi ponds, an elevator, or a bowling alley, its always about 60-70 amps for a 2500-3000 square foot house."
He was right. I did not, by the way, have the 60 amp Tesla wall charger at full blast for the test because I view that as an optional load.
So I have one 200 amp panel. As I said, 800 amps sure sounds like a lot unless its oversized for some reason.
I would suggest you do the same test, because that is the real data you need to know to get enough powerwalls.
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