Exactly! Several folks have attempted to guess but it looks like OP has not returned to clarify things.
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Is 400 amp service necessary for 3 Powerwall system?
- Thread starter Dukeybootie
- Start date
Exactly! Several folks have attempted to guess but it looks like OP has not returned to clarify things.
Sorry for the confusion -- my understanding of things was limited at the time. I am learning a lot as the responses are coming in, so thanks to all who are participating. The clarification should be whether I need a 400A MSP, now that I have a better idea of the situation.
Seems like the bottom line is this:
-there are enough homeowners out there with a large PV system and at least 3 Powerwalls running through a 200A MSP that this is clearly possible
-depending on individual setups, sometimes a 400A MSP would be required due to existing hardware limitations that could not be bypassed
Anyway, I did sign a contract a couple days ago with a vendor who said they could use the existing hardware, so no need to upgrade at this time. Will see if this remains the case after a more detailed site visit.
Seems like the bottom line is this:
-there are enough homeowners out there with a large PV system and at least 3 Powerwalls running through a 200A MSP that this is clearly possible
-depending on individual setups, sometimes a 400A MSP would be required due to existing hardware limitations that could not be bypassed
Anyway, I did sign a contract a couple days ago with a vendor who said they could use the existing hardware, so no need to upgrade at this time. Will see if this remains the case after a more detailed site visit.
According to my electrician, who I met with yesterday, a 400 amp main panel is for a major compound with multiple A/C units, a pool, and some other major major amp hog item (elevators in Beverly Hills mansions)
Three powerwalls can only output 90 amps so that’s no reason. What you ought to do as part of your diligence is to get a meter or borrow one, turn on everything in the house at once, and see what your house pulls. Did this yesterday and we were at 70 amps. By everything it was A/c, dishwasher, clothes washer and clothes dryer, every light, plus open up the refridgerated door so it turns on.
Three powerwalls can only output 90 amps so that’s no reason. What you ought to do as part of your diligence is to get a meter or borrow one, turn on everything in the house at once, and see what your house pulls. Did this yesterday and we were at 70 amps. By everything it was A/c, dishwasher, clothes washer and clothes dryer, every light, plus open up the refridgerated door so it turns on.
Also, my 16.32 system, with 35 of the 48 panels in a pure south facing roof in SoCal, only puts out 80 amps through a 125 amp sub panel.
So 400 amp panel has nothing to do with even the largest Tesla system, it would only apply if there were significant, really significant non backed up loads.
So 400 amp panel has nothing to do with even the largest Tesla system, it would only apply if there were significant, really significant non backed up loads.
With 200 amps, you're combined loads can well exceed 200 amps. I have 400 amps (800 amps of single pole breakers) coming off my 200 amp MSP. If you have a 100 amp panel, your combined loads can't exceed 100 amps, but with a 200 amp panel NEC Sec 220 has exceptions that allow the combined loads to exceed 200 amps...by a lot.
Best thing to do is if you have a 200 amp panel is do the 220 load calcs yourself if you're trying to get a handle on what's possible before an electrician shows up.
Is that what I have in their proposal? The powerwall and solar loads are clearly entering some other panel related to the GW2 BEFORE reaching my new 200amp MSP. Otherwise 200 amps wouldn't be enough to handle the existing loads plus the new power generation loads. My 200 amps is just about maxed out on loads when it comes to the 220 calcs.
The way the diagram is drawn, it looks like the new Gateway 2 with the internal sub-panel being used as the generation panel. Then, a new 200A panel being used for "relocated loads". No loads at all in the main panel.
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