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Max Charge Rate for PW2 / Excess Solar

MJ_CA_2019

Member
Aug 19, 2020
94
21
Central CA
Are PW2 limited in their charge rate to 5kW each (the same as the individual normal output maximum?).
What do you see in Storm Watch mode? (# of PW2 x 5kW)?

If so, what happens when the PV production exceeds the home load + this value?

Example:

PV producing 8 kW
Home Load: .5 kW
1 PW2 charging: 5 kW

Does the remainder export to the grid? or does the TEG try to curtail PV production?

Note: I have a 12.6 kW (DC) PV system and 3 PW2 so wont' be an issue for me, I was just curious.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
7,810
8,638
Riverside Co. CA
It exports to the grid, if you have a grid connection (as in not in a power outage). If you dont have a grid connection (as in, ARE in a power outage), it would either ramp production down (if its setup to ramp down production, which I believe is somewhat rare) or it would shut down PV production because the power had no place to go.

That would only happen in a power outage, and in the circumstance you mentioned above... PV producing more than homeload + powerwalls. A way around that would be to give the power someplace to go (plug in a car and charge it, for example).

Thats one reason why sizing number of powerwalls to fit with expected production and home consumption is important.


EDIT:
I also dont think that, charging from PV, that powerwalls accept 5 kW. I seem to remember seeing a number more like 3.3 kW per powerwall (charging) when connected to grid, but I might be mis remembering that.

I know its capable of up to 5 kW charging, and have seen that when my system is in stormwatch mode, but dont think I have ever seen that charge rate from PV.
 

darhall993

Member
Jan 24, 2019
126
109
Sandy Springs, GA
It exports to the grid, if you have a grid connection (as in not in a power outage). If you dont have a grid connection (as in, ARE in a power outage), it would either ramp production down (if its setup to ramp down production, which I believe is somewhat rare) or it would shut down PV production because the power had no place to go.

That would only happen in a power outage, and in the circumstance you mentioned above... PV producing more than homeload + powerwalls. A way around that would be to give the power someplace to go (plug in a car and charge it, for example).

Thats one reason why sizing number of powerwalls to fit with expected production and home consumption is important.


EDIT:
I also dont think that, charging from PV, that powerwalls accept 5 kW. I seem to remember seeing a number more like 3.3 kW per powerwall (charging) when connected to grid, but I might be mis remembering that.

I know its capable of up to 5 kW charging, and have seen that when my system is in stormwatch mode, but dont think I have ever seen that charge rate from PV.
I believe the 3.3 kW charge rate is during Storm Watch events, that’s what I’ve seen. From PV each Powerwall can accept up to 5kW. As the batteries approach full u will see the rate decrease
 
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wjgjr

Active Member
May 11, 2020
1,089
812
Silver Spring, MD
The Tesla Specs state that both the max charge and discharge rate is 5kW. However, there is a footnote (oddly, with nothing that references it that I see) that states "In Backup mode, grid charge power is limited to 3.3 kW." I do have my system in "Backup-only" mode, and the grid charging rate is 3.3 kW per PW for me when storm watch activates. I am, however, unclear if the "Backup mode" footnote is intended to refer to "Backup-only mode" or "Storm Watch", or both.
 
  • Informative
Reactions: jjrandorin

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
7,810
8,638
Riverside Co. CA
I could have it backwards, then.... but I thought I remembered my powerwalls showing 9.9 kW charge when being charged in stormwatch mode, but human memory is definitely fallible, lol.
 

darhall993

Member
Jan 24, 2019
126
109
Sandy Springs, GA
I could have it backwards, then.... but I thought I remembered my powerwalls showing 9.9 kW charge when being charged in stormwatch mode, but human memory is definitely fallible, lol.
Might be backup mode difference, I’m in Self Powered mode and here u can see 3 Powerwalls taking 10.6kW, my inverter is 11.4 so this is close to my max
B7DED270-609F-4528-AB83-5CB36CE3B7E6.png
 
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Reactions: jjrandorin

MorrisonHiker

S 100D 2021.4.15
Mar 8, 2015
9,447
8,607
Colorado
I've seen my 4 Powerwalls hit 13.4 kW when Storm Watch kicks in, so right around 3.3 kW each. As @wjgjr mentions, they can charge at up to 5 kW for a short time. I was able to find a video of them charging at 17.5 kW when at 88%. I might've been able to hit 20 kW if it was a little closer to solar noon and the household usage had been lower.

Screen_Recording_20200512-122357_2_1.gif
 

wjgjr

Active Member
May 11, 2020
1,089
812
Silver Spring, MD
The 3.3 kW/PW limit is specific to "grid charge power", so I would expect charging from solar to be 5.0 kW/PW continuous (with support for spikes up to 7.0 kW/PW) regardless of mode. The only thing that is unclear to me is why the 3.3 kW/PW grid charging limit would be specific to "Backup Mode" and what that means for Storm Watch if somebody was in a mode other than "Backup-only".
 

MorrisonHiker

S 100D 2021.4.15
Mar 8, 2015
9,447
8,607
Colorado
The 3.3 kW/PW limit is specific to "grid charge power", so I would expect charging from solar to be 5.0 kW/PW continuous (with support for spikes up to 7.0 kW/PW) regardless of mode. The only thing that is unclear to me is why the 3.3 kW/PW grid charging limit would be specific to "Backup Mode" and what that means for Storm Watch if somebody was in a mode other than "Backup-only".
Aha. I was confusing the grid 3.3 kW/5 kW with 5 kW/7 kW. Thanks.

Often my Powerwalls are fully charged before solar noon but if I drain them a bit more and we have a cloudless day, I bet my system could hit about 5.6 kW per Powerwall a few days this summer. Not that I'm aiming for that...but might try it once to confirm. 🤔

We use TBC, not Backup-only and still see the 3.3 kW per Powerwall limit when charging from the grid so it was probably just written wrong in the documentation.
 

h2ofun

Active Member
Aug 11, 2020
1,678
273
auburn, ca
It exports to the grid, if you have a grid connection (as in not in a power outage). If you dont have a grid connection (as in, ARE in a power outage), it would either ramp production down (if its setup to ramp down production, which I believe is somewhat rare) or it would shut down PV production because the power had no place to go.

That would only happen in a power outage, and in the circumstance you mentioned above... PV producing more than homeload + powerwalls. A way around that would be to give the power someplace to go (plug in a car and charge it, for example).

Thats one reason why sizing number of powerwalls to fit with expected production and home consumption is important.


EDIT:
I also dont think that, charging from PV, that powerwalls accept 5 kW. I seem to remember seeing a number more like 3.3 kW per powerwall (charging) when connected to grid, but I might be mis remembering that.

I know its capable of up to 5 kW charging, and have seen that when my system is in stormwatch mode, but dont think I have ever seen that charge rate from PV.
mine have charge 3.3 per PW, so with 3, 9.9
 

jhn_

Member
Jan 21, 2021
93
71
Northeast United States
Yeah I also see 5kw per PW in self-powered mode from PV.
Also have seen 5kw per PW being sent to the grid and being absorbed from the grid during “grid services” events as part of the virtual power plant our PWs are part of.
 

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