Powerwall 3 Roadmap - 3 Phase Coming!

[TJYokel]

Hi All,

Firstly, I apologize in advance for dragging up a thread from 6 weeks ago, but i was hoping that one of you would have a better understanding of how the PW3's inverter would work in the situation below (and yes i expect the info is probably still very unclear from Tesla at this stage).

If i had a PW3 with 20Kw of panels during the peak period of the day and the PW3 was charging @ 5Kw (which i think is the maximum charging rate?) and my house was using 3Kw, would the Export to the grid still be the maximum rate of 11.5 Kw?

Or is the 11.5KW Inverter limit the total of all 3 (Grid, House and Charging)thus meaning my Grid feed in the scenario above would only be 2.5Kw ?

Also if i add my Tesla MYLR into the mix and it is charging @11kw i'm assuming my Feed into the grid would be 0 during this time (well .5Kw but that would be negligible)

Thanks for your help and please use lots of crayons and small words for us uninformed....

 

[MP3Mike]

PW3 was charging @ 5Kw (which i think is the maximum charging rate?)

I think that charging limit is only when charging from AC, not solar.

Or is the 11.5KW Inverter limit the total of all 3

I think 11.5kW is the limit of how much AC can be generated from solar. But the charging may be on top of that being direct DC charging from solar.

 

[cafz]

If i had a PW3 with 20Kw of panels during the peak period of the day and the PW3 was charging @ 5Kw (which i think is the maximum charging rate?) and my house was using 3Kw, would the Export to the grid still be the maximum rate of 11.5 Kw?

Or is the 11.5KW Inverter limit the total of all 3 (Grid, House and Charging)thus meaning my Grid feed in the scenario above would only be 2.5Kw ?

The inverter is the part that converts DC to AC, so it would make sense for the inverter limit to apply to the total amount of AC generated, which would be house + export but not including charging (so in your example, 3kW house load + 8.5kW export).

 

[Vostok]

i was hoping that one of you would have a better understanding of how the PW3's inverter would work in the situation below

As @cafz mentioned, the inverter is the limiting factor as it converts the solar DC to AC for use everywhere else, including exporting and charging the battery. Almost all PW2 are AC coupled not DC coupled. IIRC, DC coupled PW2 were never sold in Australia but I could be wrong.

If PW3 with an integrated 11.5 kW inverter actually DC couples the battery (because it can) then that might mean you have 11.5 kW to run the house and export, and battery charging is not part of that limit.

The specs for US PW3 say it can AC discharge at 11.5 kW (i.e. the inverter’s limit) but peak charge rate is still 5 kW. That implies the maximum power flow at any instant of time is 16.5 kW, and your solar will be capped if/when it hits that number.

In most cases that shouldn’t be much of an issue since few solar arrays are so perfectly oriented / not overshadowed such that they output their peak nameplate power for any significant length of time. A rule of thumb I’ve seen is inverters are typically dimensioned to 75% the solar nameplate.

Taking out 5 kW DC charging of the battery, you’re left with 15 kW of solar, and 75% of that is 11.25 kW, i.e. just under the 11.5 kW inverter limit. So it all seems to add up.

 

[JonDarian]

I can't say what the PW2 can do, but will offer a PW2 data point. I have 20kW of panels and a 15kW inverter, along with a PW2. Because I live in the tropics, it is quite common for my system to have filled the battery and be exporting close to 15kW for a few hours in the middle of the day (the inverter limit, minus the household consumption). This is through the hotter months. Depending on where you live, it may not be reasonable to assume that you will be using 5kW of your peak production to fill your battery, as it may already be full by the time the peak arrives.

 

[MP3Mike]

but peak charge rate is still 5 kW.

Is that true even for DC charging? The specs only mention the limit for AC charging:

 

[Vostok]

Is that true even for DC charging? The specs only mention the limit for AC charging:

View attachment 1049528

If the specs don’t say, then we don’t know. I was making an assumption on the basis of the information we do have. So a clarification from Tesla would be nice…

 

[TJYokel]

Taking out 5 kW DC charging of the battery, you’re left with 15 kW of solar, and 75% of that is 11.25 kW, i.e. just under the 11.5 kW inverter limit. So it all seems to add up.

Thanks for the Clarification, and yes there is still a lot of unknowns but hopefully these will be cleared up before i'm ready to upgrade my system at home.

Right now i have 12Kw of panels into a 10Kw inverter on a Curved roof that i'm looking to expand to 20kw. Given the expansion i know i'm up for a new inverter so i either will just get a standalone inverter, extra panels and 1-2 PW2's or Panels and 1-2 PW3's (or 1 PW3 with an expansion pack)

This all really depends on PW3's ability to support 3 phase becoming a reality and not a glitch in the "Elon Reality Matrix"

We already have 1 Tesla and the wife is applying pressure to replace the 2nd car soon for another one so we will probably end up with 2 Wall chargers to accommodate.


Once thanks to everyone for chiming in and offering support