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Can I have 1 powerwall with a 11.4kW PV system?

s.kuo

Member
Aug 28, 2016
20
4
California
I'm getting different information from different Tesla certified installers. Hoping somebody on here can help.

I have existing solar with a Solar Edge 11.4 kW inverter. I have a Powerwall that I received from the referral rewards that I am trying to get installed. I've gotten installation quotes from two certified installers already but they are telling me different things.

One installer is saying that he will put in a sub panel for my backup loads as well as the Powerwall. He will also move the solar from the main panel to the new sub panel so that I can charge the Powerwall using solar during power outages.

The second installer will also put in a new sub panel for the backup loads and Powerwall. But, he cannot move the solar from the main panel to the sub panel. He is saying my inverter is too large and may possibly fry the Powerwall during a power outage.

Which installer is correct here? The first one seems ideal, since it makes the most sense to be able to charge the Powerwall using solar during outages. Thanks in advance for any insight you can offer.
 

h2ofun

Active Member
Aug 11, 2020
2,679
492
auburn, ca
I'm getting different information from different Tesla certified installers. Hoping somebody on here can help.

I have existing solar with a Solar Edge 11.4 kW inverter. I have a Powerwall that I received from the referral rewards that I am trying to get installed. I've gotten installation quotes from two certified installers already but they are telling me different things.

One installer is saying that he will put in a sub panel for my backup loads as well as the Powerwall. He will also move the solar from the main panel to the new sub panel so that I can charge the Powerwall using solar during power outages.

The second installer will also put in a new sub panel for the backup loads and Powerwall. But, he cannot move the solar from the main panel to the sub panel. He is saying my inverter is too large and may possibly fry the Powerwall during a power outage.

Which installer is correct here? The first one seems ideal, since it makes the most sense to be able to charge the Powerwall using solar during outages. Thanks in advance for any insight you can offer.
I have 2 11.4 SE inverters connected to my 2 banks of PW's I have heard of no reasons to be concerned but why is this guy saying that?
 
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s.kuo

Member
Aug 28, 2016
20
4
California
I have 2 11.4 SE inverters connected to my 2 banks of PW's I have heard of no reasons to be concerned but why is this guy saying that?
He is saying the 11.4 kW is too much for the Powerwall to handle and could fry. He is saying the Powerwall can only handle 5 kW and that I would need to swap out my inverter for two smaller inverters so that one of them could charge my Powerwall.
 

wjgjr

Active Member
May 11, 2020
1,257
999
Silver Spring, MD
I have 2 11.4 SE inverters connected to my 2 banks of PW's I have heard of no reasons to be concerned but why is this guy saying that?
I certainly am not an expert on all of this, but I think the reason is OP has only a single PW, which can only handle 5 kW continuous and 7 kW surge (and I am assuming this PW does not have any of the newer, higher limits.) A 11.4 kW inverter would likely put out more than that during the middle of the day and would, at the least, cause the system to repeatedly go offline if the system is off-grid (though I would hope breakers would trip rather than frying anything.) On-grid should work since power can be sent to the grid (presumably.)
 

s.kuo

Member
Aug 28, 2016
20
4
California
I certainly am not an expert on all of this, but I think the reason is OP has only a single PW, which can only handle 5 kW continuous and 7 kW surge (and I am assuming this PW does not have any of the newer, higher limits.) A 11.4 kW inverter would likely put out more than that during the middle of the day and would, at the least, cause the system to repeatedly go offline if the system is off-grid (though I would hope breakers would trip rather than frying anything.) On-grid should work since power can be sent to the grid (presumably.)
Not sure if it has the newer higher limits you are speaking of. It is a red Powerwall 2.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,623
10,856
Riverside Co. CA
Basically, you are supposed to have 1 powerwall per, at maximum, 7.6 kW of PV. You have an 11.4 kW inverter, so you almost assuredly are generating more power than one powerwall can take. During an outage, your PV would generate too much power for the powerwall, so the powerwall would shut down, thus shutting down your solar.


I am fairly sure that "installer 2" who says you cant hook your 1 powerwall up to that size PV system and expect it to operate in an outage, is correct from what we understand about the current product.

The "new" powerwall is a powerwall+ (stickied thread up top) which we dont have tons of info on, but the red referral powerwall is almost assuredly the same powerwall 2 we all know now.

If you go with installer 1 and they hook it up that way, then you test it right now (during the day, during spring / summer), you will likely find out that installer 2 was correct, and it wont work during an outage (your home electrical will shut down anytime your PV is generating more than 5kW continuous power, which for a 11.4 sized PV will be quite a long time during the day).

Your only "good" option is to buy another powerwall and install 2. otherwise, you would be installing a powerwall, but not have use of power in a power outage, negating one of the main reasons for having a powerwall. Let me rephrase that.... you would have use of 1 powerwall during the outage, until it ran out of power because it could not be re charged from your solar.

Depending on how your PV (solar) is setup it "could" be possible to have only some of the panels active during a power outage, reducing the amount of solar that could be generated during an outage to an amount that 1 powerwall could theoretically take, but those considerations normally would be done on install of the PV, and since the PV is installed already, thats unlikely to be possible without considerable expense.

If you dont want to buy another powerwall and install 2, you likely should just sell that one, or at least I would. I cant see paying to install a powerwall and not having backup during a power outage.

This thread has a TMC members experience with this. It was not 1 powerwall, but the situation was the exact same ("not enough powerwalls for amount of PV").



==============================

(moderator note: changed thread title to one that better describes what you are asking)
 
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s.kuo

Member
Aug 28, 2016
20
4
California
Basically, you are supposed to have 1 powerwall per, at maximum, 7.6 kW of PV. You have an 11.4 kW inverter, so you almost assuredly are generating more power than one powerwall can take. During an outage, your PV would generate too much power for the powerwall, so the powerwall would shut down, thus shutting down your solar.


I am fairly sure that "installer 2" who says you cant hook your 1 powerwall up to that size PV system and expect it to operate in an outage, is correct from what we understand about the current product.

The "new" powerwall is a powerwall+ (stickied thread up top) which we dont have tons of info on, but the red referral powerwall is almost assuredly the same powerwall 2 we all know now.

If you go with installer 1 and they hook it up that way, then you test it right now (during the day, during spring / summer), you will likely find out that installer 2 was correct, and it wont work during an outage (your home electrical will shut down anytime your PV is generating more than 5kW continuous power, which for a 11.4 sized PV will be quite a long time during the day).

Your only "good" option is to buy another powerwall and install 2. otherwise, you would be installing a powerwall, but not have use of power in a power outage, negating one of the main reasons for having a powerwall. Let me rephrase that.... you would have use of 1 powerwall during the outage, until it ran out of power because it could not be re charged from your solar.

Depending on how your PV (solar) is setup it "could" be possible to have only some of the panels active during a power outage, reducing the amount of solar that could be generated during an outage to an amount that 1 powerwall could theoretically take, but those considerations normally would be done on install of the PV, and since the PV is installed already, thats unlikely to be possible without considerable expense.

If you dont want to buy another powerwall and install 2, you likely should just sell that one, or at least I would. I cant see paying to install a powerwall and not having backup during a power outage.

This thread has a TMC members experience with this. It was not 1 powerwall, but the situation was the exact same ("not enough powerwalls for amount of PV").



==============================

(moderator note: changed thread title to one that better describes what you are asking)
Thank you for this info.
 

charlesj

Active Member
Oct 22, 2019
1,197
254
Monterey, CA
Yes, in that grid down condition the inverter would be shut down on a high producing day, perhaps in the spring, summer, fall cycle but may not in winter.
However, this would also happen with 2 PW that are full and house cannot use the all the solar. The battery would supply power until it is drained to some level then recharge and supply house by solar. The cycle would repeat.
However, if PV inverter is producing more than house and battery limit of 5kW can use, perhaps that is where the issue really comes up?
Turn on the whole house? :D
 

h2ofun

Active Member
Aug 11, 2020
2,679
492
auburn, ca
I have 11.2 kW of solar and three powerwalls. Wish I had three more with PG&E turning off the power for days at a time around here.
IMO, I have 5 PW's and even though it would be "cool" to have more, unless one really has money to burn. I could care less how long PGE turns off
the power. The limiter is recharging them! This is why I have just put another 15KW of solar on my house. I just need enough batteries to run the house while the sun is down. THEN I need as much solar as I can to get batteries recharged, and run the house. I feel I now have this best balance vs cost.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,623
10,856
Riverside Co. CA
Yes, in that grid down condition the inverter would be shut down on a high producing day, perhaps in the spring, summer, fall cycle but may not in winter.
However, this would also happen with 2 PW that are full and house cannot use the all the solar. The battery would supply power until it is drained to some level then recharge and supply house by solar. The cycle would repeat.
However, if PV inverter is producing more than house and battery limit of 5kW can use, perhaps that is where the issue really comes up?
Turn on the whole house? :D

The difference in this situation between the 1 powerwall situation and 2 powerwall situation is this, in a GRID DOWN situation

With 2 powerwalls, the PV would provide solar to the powerwalls until they are full, then the PV would cycle off and on, while the powerwalls carry the home load... Provided this OPs PV install does not generate more than 10kW continuous solar power during the day).

With 1 powerwall (with that size PV) when the grid went down on a bright sunny day that isnt the middle of winter, the system would be producing enough PV to overload the powerwall and it would instantly shut off (and not be able to be re started until either the grid came up, or the PV was turned off, if even then). This PV definitely generates more than 5kW continuous, if the inverter is 11.4kW.

With a PV that large (if the inverter is 11.4,. the PV system is likely larger than even that) it will generate more PV than the powerwall can intake. In a "grid up" situation its not an issue, because the excess will always go to the grid. In a grid down situation it wont work unless the system is configured to only power "some" of the panels during a grid down situation. Whether that is possible (without high costs) on an existing PV setup I have no idea.

If installing new, it could theoretically be configured that way (although it would still be better to just get another powerwall).
 
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jazzkat

New Member
Jun 17, 2021
1
2
Adelaide, SA Australia
I have 21kW PV with one Tesla PowerWall 2. It's not a problem, because PowerWall is installed along with the Tesla Gateway 2 which is the gatekeeper. The inbound inverter on the PowerWall will only ever receive its 5kW inbound capacity. And for backup protection, only a few key circuits are connected for backup power via the Gateway. I'm about to add a 2nd battery, but just to store extra, not because there's any problem with current system.
 
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Zinc_Saucier

Member
Jul 30, 2020
46
27
Massachusetts
I have 21kW PV with one Tesla PowerWall 2. It's not a problem, because PowerWall is installed along with the Tesla Gateway 2 which is the gatekeeper. The inbound inverter on the PowerWall will only ever receive its 5kW inbound capacity. And for backup protection, only a few key circuits are connected for backup power via the Gateway. I'm about to add a 2nd battery, but just to store extra, not because there's any problem with current system.
Have you tried disconnecting from the grid when your PV is generating >house load + 5kW? In that example, where does the excess solar go if the PW maxes out at 5kW and your house isn’t drawing the balance? Or do you have multiple inverters with only one tied into the backup side?
 

charlesj

Active Member
Oct 22, 2019
1,197
254
Monterey, CA
I have 21kW PV with one Tesla PowerWall 2. It's not a problem, because PowerWall is installed along with the Tesla Gateway 2 which is the gatekeeper. The inbound inverter on the PowerWall will only ever receive its 5kW inbound capacity. And for backup protection, only a few key circuits are connected for backup power via the Gateway. I'm about to add a 2nd battery, but just to store extra, not because there's any problem with current system.
If you are willing to test as @Zinc_Saucier suggested, turning off the grid breaker, see if battery is powering the house when battery is fully charged or close to it while PV inverter/s turned off. Some suggest whole system will be off under such conditions with 1 PW and such a large PV system. Or at least that was my understanding from reading the post.
 

arnolddeleon

Supporting Member
Jul 21, 2012
842
910
SF Bay Area
I'm getting different information from different Tesla certified installers. Hoping somebody on here can help.

I have existing solar with a Solar Edge 11.4 kW inverter. I have a Powerwall that I received from the referral rewards that I am trying to get installed. I've gotten installation quotes from two certified installers already but they are telling me different things.

One installer is saying that he will put in a sub panel for my backup loads as well as the Powerwall. He will also move the solar from the main panel to the new sub panel so that I can charge the Powerwall using solar during power outages.

The second installer will also put in a new sub panel for the backup loads and Powerwall. But, he cannot move the solar from the main panel to the sub panel. He is saying my inverter is too large and may possibly fry the Powerwall during a power outage.

Which installer is correct here? The first one seems ideal, since it makes the most sense to be able to charge the Powerwall using solar during outages. Thanks in advance for any insight you can offer.
Find out if your Solar Edge inverter has the feature described on page 6 of this document:

Application Note - Power Control Options (solaredge.com)

If it does then you should have minimal issues.

Beyond that, @jjrandorin already explained what happens when you have two much solar generation and not enough load and battery to sink it.
 

KJD

Supporting Member
Dec 14, 2013
1,352
1,009
SLC, UT
He is saying the 11.4 kW is too much for the Powerwall to handle and could fry. He is saying the Powerwall can only handle 5 kW and that I would need to swap out my inverter for two smaller inverters so that one of them could charge my Powerwall.
That seems like a waste of money to me. What is the cost of 2 new inverters compared to buying a 2nd Powerwall ?

Might be worth while with all the grid problems as of late.
 

Zinc_Saucier

Member
Jul 30, 2020
46
27
Massachusetts
If you are willing to test as @Zinc_Saucier suggested, turning off the grid breaker, see if battery is powering the house when battery is fully charged or close to it while PV inverter/s turned off. Some suggest whole system will be off under such conditions with 1 PW and such a large PV system. Or at least that was my understanding from reading the post.

If the PW is full, no matter if there’s too much solar or not, it should raise the frequency to turn off the PV. The real test is what happens when the PV should be charging the PW but the PV is producing >5kW + house load.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,623
10,856
Riverside Co. CA
If the PW is full, no matter if there’s too much solar or not, it should raise the frequency to turn off the PV. The real test is what happens when the PV should be charging the PW but the PV is producing >5kW + house load.

Read through the thread I linked in post #6, for someone who had more PV than their powerwalls could take in.
 
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Zinc_Saucier

Member
Jul 30, 2020
46
27
Massachusetts
Read through the thread I linked in post #6, for someone who had more PV than their powerwalls could take in.
Probably should have read that before, but in that case it’s interesting that their system wouldn’t work even with only one of the inverters running. Just skimmed the whole thread but didn’t see any specific resolution to that (other than just adding a 3rd PW to soak up the PV capacity)
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,623
10,856
Riverside Co. CA
Probably should have read that before, but in that case it’s interesting that their system wouldn’t work even with only one of the inverters running. Just skimmed the whole thread but didn’t see any specific resolution to that (other than just adding a 3rd PW to soak up the PV capacity)

That was the resolution (adding the additional powerwall).
 

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