Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

New Install Tomorrow (Solar + 2 Powerwalls)

This site may earn commission on affiliate links.
I have a few questions regarding an attempt at a "Whole Home Backup" install.

I live in Florida and in my area we seem to have short spurt outages from .5 - 3 hours outages during the rainy season quite often. Aside from the obvious scenario of a hurricane, the main reason I got the Powerwalls was in hopes to continue life uninterrupted by the shorter outages due to random thunderstorms.

I was wondering if it is possible to power a 3.5 ton A/C with two Powerwalls for a short period of time. It seems that the information I am getting ranges from "it will do it but just drain the batteries quicker" to "it depends on if the LRA value is less than the 60A that two powerwalls can provide". I am not sure which one of those answers is accurate. The LRA of my outdoor unit is 109.

If the LRA answer is correct, would it be smart to let them install the batteries to back up the whole home and then later install a "soft start" module. I was thinking in this scenario I'd have to avoid turning the A/C if I was in backup mode until I get the soft start module installed.

I guess ultimately, I am trying to avoid having them setup my system in a way that will add more work later if I want to backup the entire house later"


Forgive my ignorance as I am new at all of this.
 
Just saw this post from user runfarnn -

"Here is what the Tesla engineer designing our system provided as specs for a 2 PW set up (with two A/C units).

The LRA for each unit is 58 amps or less

OR

The LRA is 140A or less AND the unit has a scroll compressor."



I have confirmed that my unit does indeed have a scroll compressor. So does a combo of LRA 109A and scroll compressor sound safe for two Powerwalls ?


Thanks.
 
I recently had Solar and Powerwalls installed in FL. I am backing up two 3 ton AC units and the Tesla installers installed soft start modules on each unit to compensate for the hard starts. Your team should be doing the same if the AC unit is a part of your Powerwall backup design.
 
Just saw this post from user runfarnn -

"Here is what the Tesla engineer designing our system provided as specs for a 2 PW set up (with two A/C units).

The LRA for each unit is 58 amps or less

OR

The LRA is 140A or less AND the unit has a scroll compressor."



I have confirmed that my unit does indeed have a scroll compressor. So does a combo of LRA 109A and scroll compressor sound safe for two Powerwalls ?


Thanks.

If you have the scroll compressor, it works just like a soft start device, no need to have them install that. You should be good to go.

In my experience, Tesla engineering was very conservative, and if they have any indication you will push past peak draw, they won't let you wire up a whole house backup (this is the reason we had to go for 3 PW2s, instead of the originally planned 2).
 
I guess the only difference than my install and others is that I didn’t work with Tesla. I worked with a local company called Maximo Solar. They had several Powerwalls on hand so I jumped on it since I was doing solar anyway.

Hopefully it either works like the above poster or the installers can put a soft starter in place.