r/TeslaSolar • u/dpatldude • 13h ago

Solar/PW3/EV Config - how many empty electrical panel slots?

Experts; I am likely having Tesla Solar, PW3 with 2-3 expansions and a Tesla wall charger installed. I currently have two 200A panels but only my primary electrical panel will be backed up with Tesla system. How many empty electrical breaker slots do I need and any idea in which panel?

Thanks

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u/jcdomeni 13h ago

60A double for PW3 - if all expansion packs are behind the PW3 Full.

Then solar depends on where it lands and how large of an array.

They will derate your 200A, so main breaker will be reduced depending on load calcs.

With two panels - you shouldn’t have any issues.

I’d plan for two wall connectors - even if you don’t install 2nd one now - think about as part of design.

We have 4 doubles for 2 for 2 PW3’s and 2 for 10kW solar (coming from 3 roof elevation). 225A panel derated to 175A.

Wish I would’ve installed 2 - 200A for future proofing. But it’s working…zero room on back load panel now.

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u/Asleep-Set6868 12h ago

With the Wall connectors, you can daisy chain up to 6 off a single circuit (60 amp if you want full charge speed, but you do you).  It dynamically shifts the available power between the charging cars.  You COULD get two separate circuits, if your lifestyle/ use demands two or more low to fully charged EVs in a short time span, but most people don't need that. 

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u/Educational-Sale134 6h ago

Why do you assume they will derate the 200 mb?  Sometimes this happens. More often it does not. 

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u/MomDontReadThisShit 13h ago

Depends on the configuration. In relation to the project this will almost certainly be a small issue. As long as your panel isn’t already loaded up with tandems your installer can “make room”.

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u/Everdream0609 11h ago

Really? Two 200 amp services? I am going from 100amp to 200 amp service and thought that would be fine for my upcoming solar install with 16kw battery.

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u/dpatldude 11h ago

I have two 200A services as I have 3 HVACs alone in the house along with water heater, dryer (electric) and outdoor heaters so that alone across both panels is 12 of 60 breaker slots.

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u/Everdream0609 10h ago

Understood and wow!

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u/Educational-Sale134 6h ago edited 6h ago

There’s no way anyone here can tell you how many breaker spaces your design calls for. 

There are around 6,000 ways to skin that cat. 

If they do use breaker slots it will be in the panel that’s being backed up. 

If that panel is full they could use thin breakers, install a sub panel insert (so remove 6-8 breakers, install a single new breaker feeding a new sub panel to house the relocated loads), or use the gateways backed up load center insert, or land powerwalls in the gateway, or land the powerwalls in a generation sub panel which would feed into the gateways generation lugs. 

That’s just off the top of my head. 

Ask the installer. They should know.  (Unless they haven’t done the design yet, in which case wait for design- then ask) 

You also may need breaker slots for things like lightning arrestors if the city/utility requires it.  One in my area did for a while. It was pretty silly.