Can two Tesla solar systems be merged to one group of PWs?

[preilly44]

I'm doing a new construction with an 18kw solar glass roof with 4 PWs and a 7kw panel system on the guest house (the roof is to steep for SGR). I had to order the two systems separately but want both solar systems to feed the 4 PWs. Is that going to be possible? Also, I have 400 amp service if that changes anything? I'd like to do whole house backup with the 4 PWs. I was told I'm getting a Gateway 2 if that helps?

Thanks in advance!

 

[jboy210]

The question in my mind is if the inverters for the installation are all controllable by the same Gateway. In my mind that would be a factor. But, obviously you need to put this question to Tesla or whomever is installing the Gateway, inverters, etc.

 

[BrettS]

Feeding the powerwalls from multiple solar systems is definitely not a problem. I just had a 15.12kW solar system installed and I have two 7600kW inverters. My powerwalls are fed by both inverters. I’ve also seen people who have an old solar system and then add a new one and feed their powerwalls from both systems.

However, you did mention a couple of other things that could be potential problems. You mentioned that you have a house and a guest house, so in order for them to be served by the ‘combined’ solar systems and share the powerwalls then they would need to be on the same electrical system with a single meter. Assuming that’s the case, then it should be no problem. The distance between the houses may be of some consideration as there will likely need to be some wires trenched between them.

The other concern is your 400A service. Unfortunately, as of right now the gateway (1 and 2) only support 200A. Typically what I see done in the case of people with 400A service is that they split it into two 200A systems. So you would have two gateways and two powerwalls each feeding 200A. There are some other threads on here about what people have done in the case of 400A service.

 

[CrazyRabbit]

Your installer who is doing the PW should do a loads calculation to see if you can run the whole main house off of one gateway. But you you will need a non backup panel with probably the guest house off it..
Another thing, when running off grid the powerwalls, powerwalls can only consume 5KW each, and if you are producing18+7=25KW at any given time you will cause the powerwalls to reset. Depending on panel orientation (East, south, or west) it might not be a problem. It might be better to put the 7kw system on the guest house so it doesn’t feed the PW in a off grid situation, or you can just add another PW.