Need an additional panel for adding PW

[ARG-EV]

I am considering adding 1 PowerWall to pair with my existing 3.36 kW solar system in Oakland, CA (PG&E territory). The solar panels each have their own enphase microinverter.

The two contractors we have received quotes from have said that even though I have a 200 A main panel with in-built service disconnect which my PV feeds into, along with several open breaker slots, I will still need an additional, new 200 A panel when installing the PW. They confirmed that this second panel would be additional to the Gateway.

This seems like an awfully wasteful use of space that I don't necessarily have in my small 1941 home. Can someone help me by explaining why I need a new additional panel?

 

[h2ofun]

I am considering adding 1 PowerWall to pair with my existing 3.36 kW solar system in Oakland, CA (PG&E territory). The solar panels each have their own enphase microinverter.

The two contractors we have received quotes from have said that even though I have a 200 A main panel with in-built service disconnect which my PV feeds into, along with several open breaker slots, I will still need an additional, new 200 A panel when installing the PW. They confirmed that this second panel would be additional to the Gateway.

This seems like an awfully wasteful use of space that I don't necessarily have in my small 1941 home. Can someone help me by explaining why I need a new additional panel?

Seems that is a lot of powerwalls for so little solar?

 

[CrazyRabbit]

Why can’t they land the powerwall on the optional Panel board in the gateway.

 

[dhrivnak]

I am considering adding 1 PowerWall to pair with my existing 3.36 kW solar system in Oakland, CA (PG&E territory). The solar panels each have their own enphase microinverter.

The two contractors we have received quotes from have said that even though I have a 200 A main panel with in-built service disconnect which my PV feeds into, along with several open breaker slots, I will still need an additional, new 200 A panel when installing the PW. They confirmed that this second panel would be additional to the Gateway.

This seems like an awfully wasteful use of space that I don't necessarily have in my small 1941 home. Can someone help me by explaining why I need a new additional panel?

Strange, I know this is not the case with the similar FranlkinWH. But I do not know the details of a PowerWall.

 

[jgleigh]

A single Powerwall only needs a 30A breaker. Something isn't right here.

 

[arnolddeleon]

My guess is that Powerwall breaker (30A) and your existing solar (20A) would exceed the allowed backfeed to your existing main panel. But as I understand it the Powerwall has PCS (Power Control System) capabilities so it can manage the the backfeed so it never exceeds the bus bar ratings.

The other possibility is they can't use the "backup switch" and your combo panel doesn't have a "legal" way for the gateway to get between the grid and your loads so they will essentially be transferring all your loads to the new panel. As I think about it this is the most likely scenario.

 

[CrazyRabbit]

MY guess is need new panel for non backed up loads. They don’t want to l overload the powerwalls.

 

[SoundDaTrumpet]

I suggest asking about putting the PW Gateway on the largest branch circuit you can muster. I have mine on a 125A branch circuit. I put nearly everything behind the gateway minus my A/C and Tesla Wall Connector. Keep in mind that my system is a partial home backup (almost whole!) and not a whole home backup. I did this to avoid the whole new service panel. It was a price conscious decision to do a $800 labor install back when Tesla Energy was bleeding red on their PW-only installations.

Caveat: Knowingly, this does limit my system ability for additional solar and Powerwalls in the future. I have an order to add 20A of more solar, which will put me at the limit of a 125A branch breaker.

 

[ARG-EV]

My guess is that Powerwall breaker (30A) and your existing solar (20A) would exceed the allowed backfeed to your existing main panel. But as I understand it the Powerwall has PCS (Power Control System) capabilities so it can manage the the backfeed so it never exceeds the bus bar ratings.

The other possibility is they can't use the "backup switch" and your combo panel doesn't have a "legal" way for the gateway to get between the grid and your loads so they will essentially be transferring all your loads to the new panel. As I think about it this is the most likely scenario.

I think you maybe right. I currently have enphase microinverters in all my solar panels and those feed into a 15A breaker on my meter + 200 A combo panel. My understanding is that because the gateway needs to be right downstream of the meter before power flows to the house, the combo panel somehow does not permit them to place it in between the meter and the breakers.

Ugh, it's gonna look really ugly unfortunately. I wonder if they can take out my existing combo panel and replace it with just a meter if such a move is allowed

 

[CrazyRabbit]

If your willing to pay the premium, then I would ask Tesla to design the system with expansion in mind so you can add more PW and solar without starting over.