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Can I run a A/C on my system

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
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17,964
Riverside Co. CA
I have one Powerwall in the garage and 40 panels on the roof.
The installer told me my A/C could not be connected to the Powerwall.
So when we do not have power - we also have no A/C.

Is that a true statement.?

Thanks
With one Powerwall, that is almost assuredly a true statement.
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
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Nov 28, 2018
14,222
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Riverside Co. CA
He could get a few hours. :)

No, he could not, you are confusing the OP. Its not connected, so he cant get "any" hours, and it was not connected because the start up was not supported by 1 powerwall, meaning trying to start the AC would shut down the powerwall.

So, no, in his situation with 1 powerwall, he could not have had it connected, nor get "any" hours.
 

h2ofun

Active Member
Aug 11, 2020
3,613
867
auburn, ca
No, he could not, you are confusing the OP. Its not connected, so he cant get "any" hours, and it was not connected because the start up was not supported by 1 powerwall, meaning trying to start the AC would shut down the powerwall.

So, no, in his situation with 1 powerwall, he could not have had it connected, nor get "any" hours.
Yep, but I was responding to the post that said but if you could get it started, how ever that happened,.... But with the new 2.1 PW with 50% more output to 7.5hw, maybe he might have a little better chance. :)
 
In general no- you probably need 2 PWs or more to have AC. That being said I have 3 CAC units- a 4 ton, 3 ton and a cassette style/inverter mini split. Last summer (pre solar/PWs) we lost power for 2 days. It's actually the reason we signed up for our system. Anyways, I hooked up my 6k gen to the house and ran the whole house off it. I decided to try running the mini split and to my surprise it didn't even load the generator. For reference when my coffee pot or microwave turn on you can hear the gen working harder. Not a peep with the split. And I was able to pull a ton of moisture out of the air during august. Just saying that if you have the right unit it might work...
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
14,222
17,964
Riverside Co. CA
I do not have it, and it was explained to me, but my friend has the same installer and system with less panels. He says his A/C runs on the PW. I don't believe him

IF your friend has one powerwall (thats not clear), then its possible that there is some miscommuniation going on here. It IS possible that your friends system is wired in such a way that the powerwall can see the AC unit "upstream" from it, and provide power to the AC unit WHEN THE GRID IS UP / CONNECTED.

In caps, just to call it out, not to yell. Its possible for systems to be wired in such a way to see the AC and provide power to it when the grid is up. That does not mean that the AC would operate when the grid is down.

So, "My AC runs off the powerwall" could be a true statement when the grid is up. It also sounds like you have a pretty large PV system, but since you only have 1 powerwall, they definitely would have had to do some connection gymnastics to move loads to a critical loads panel. For all I know, your system might also be configured so the powerwall can provide power to the AC when the grid is up, but thats not what you asked. You wanted to know about grid down.

Your friend either has 2 powerwalls, is talking about a portable AC unit that plugs into a wall socket, or talking about running the AC when the grid is up.
 
The main hurdle with running A/C from a Powerwall is the start current requirement. Some newer high efficiency A/C units use inverter technology so the start current isn't significantly higher than the running current. So if you have one of the newer A/C units and it is small enough to only need about 20 amps to run then yes you should be able to run A/C. Or there are soft start devices that can lower the starting current requirement of more conventional A/C units. But it is unlikely to work with just one Powerwall.
The other main problem A/C would drain the Powerwall really quickly unless you are also have solar generating at the same time.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
14,222
17,964
Riverside Co. CA
ok all good info, I am calling my friends bluff, and saying he is wrong. he has one PW, and a small house. he is very challenged when it comes to technology. thanks team for the replies.

If this is a friend such that you visit their home (for some, the modern definition of "friend" has changed, lol), just tell them to show you, by turning off the main breaker and letting the powerwall power the home, then turning on the AC.
 
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We have a small cluster of homes in the neighborhood with solar and powerwalls.
Site with 1 powerwall (8kW solar) cannot run any 220 devices during a failure.
Site with 3 powerwalls (12 kW solar) can run the whole house including AC during an outage.
Site with 2 powerwalls (10kW solar) can run the whole house including AC during an outage - however - my 3 ton AC has a really serious startup compressor kick that will trip the powerwalls at night. I can run during the day because the solar provides the additional support. I have to shut down my AC at night. It is a known and acknowledged issue that I was initially not going to be allowed to do a whole house backup - serious technical discussion with my engineer and it was allowed when I clearly accepted the operational limitation. My compressor will not accept the the usual soft start electrical modification. I should have thought to simply increase my PW install to 3 instead of 2. Brain fart on my part.
 
Site with 2 powerwalls (10kW solar) can run the whole house including AC during an outage - however - my 3 ton AC has a really serious startup compressor kick that will trip the powerwalls at night. I can run during the day because the solar provides the additional support. I have to shut down my AC at night. It is a known and acknowledged issue that I was initially not going to be allowed to do a whole house backup - serious technical discussion with my engineer and it was allowed when I clearly accepted the operational limitation. My compressor will not accept the the usual soft start electrical modification. I should have thought to simply increase my PW install to 3 instead of 2. Brain fart on my part.
I'm in a similar situation. My 2 Powerwall whole house backup was supposed to be able to run my Carrier heat pump but Tesla didn't catch that their soft start device isn't compatible with the reverse run compressor. My compressor will only start if the solar is producing. Since the batteries quickly recharge without the AC running and the Gateway then commands the solar panels off there is only a small window to start the compressor. It is a PITA.
I've been waiting since June for Tesla to come up with a solution but they keep putting me off. I'm hoping the potential for increased output of the Powerwalls per Elon's tweet will help my situation.
 
Yeah - I have the same hopes about Elon's recent tweet. My one issue with my install is that startup draw. Otherwise, I have been thru more than 20 significant outages (longest 31 hours) with no issues. Have even tossed an extension cord over to a neighbor so he could keep his fridge, freezer and critical medical equipment running during a local firestorm induced outage.
 

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