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Powerwall 2 with inverter vs external inverter

I've done quite a bit of research on this, but I've had a hard time finding reliable information. My wife and I are interested in adding solar to our home, but she is (understandably) concerned about the number of boxes that will be on our walls. I see that the Powerwall 2 comes in a model that has an inverter built in, yet all of the videos of setups I've seen online involve a separate, external inverter.

Is there an advantage to having an external inverter? We're really just looking for our solar setup to do the usual things:
  • Have the solar power the house and charge the Powerwall 2 (when it can)
  • Run the house off of the Powerwall 2 when the solar drops out
  • Use utility power as little as possible
From my understanding, if we eliminate the external inverter, we'd just four boxes:
  1. The breaker box (which we already have)
  2. Utility box (which we already have)
  3. The Powerwall 2
  4. Tesla Gateway
Any insight would be appreciated! Thanks!
 

mongo

Well-Known Member
May 3, 2017
16,112
58,129
Michigan
I've done quite a bit of research on this, but I've had a hard time finding reliable information. My wife and I are interested in adding solar to our home, but she is (understandably) concerned about the number of boxes that will be on our walls. I see that the Powerwall 2 comes in a model that has an inverter built in, yet all of the videos of setups I've seen online involve a separate, external inverter.

Is there an advantage to having an external inverter? We're really just looking for our solar setup to do the usual things:
  • Have the solar power the house and charge the Powerwall 2 (when it can)
  • Run the house off of the Powerwall 2 when the solar drops out
  • Use utility power as little as possible
From my understanding, if we eliminate the external inverter, we'd just four boxes:
  1. The breaker box (which we already have)
  2. Utility box (which we already have)
  3. The Powerwall 2
  4. Tesla Gateway
Any insight would be appreciated! Thanks!

USA version of PW2 only comes in the AC (inverter built in) version.
So your box count is correct, unless there is one more for backed-up loads.
 
USA version of PW2 only comes in the AC (inverter built in) version.
So your box count is correct, unless there is one more for backed-up loads.

Thanks! That's good to know, I'm assuming that's a recent change though right? I was just watching this video of an install that happened back in April/May of this year, and he has a separate inverter. Particularly confusing because the entire thing (panels, Powerwall, etc.) was performed from scratch by Tesla / SolarCity, he wasn't retrofitting anything.

Also pardon my ignorance, one more what for backed-up loads? Another battery?
 

mongo

Well-Known Member
May 3, 2017
16,112
58,129
Michigan
Thanks! That's good to know, I'm assuming that's a recent change though right? I was just watching this video of an install that happened back in April/May of this year, and he has a separate inverter. Particularly confusing because the entire thing (panels, Powerwall, etc.) was performed from scratch by Tesla / SolarCity, he wasn't retrofitting anything.

Also pardon my ignorance, one more what for backed-up loads? Another battery?

It's been that way for a while. PW1 had the option of being DC only.
Watched part of the video, the inverter mentioned is for the solar DC to AC conversion. If you run your solar as one string, you will have a similar box. If you use microinverters on each panel, then no inverter box. The PW2 interfaces only with the AC supply from the breaker panel, so solar setup does not directly impact it.
If you add a backed up load panel, that will increase the total box count by one. This will likely be needed based on your house loads and number of PWs.
 
We got our system installed last week and should have permission to operate from the utility company tomorrow. My wife and I didn't want the side of our house littered with equipment so we opted to have the power walls and inverters installed in the garage. All of the conduit was painted to match the brick and walls and blend into the house very well. One very important thing you don't learn until your in-home consultation is if you own and charge your Tesla at home you will need to budget for two (2) Powerwalls.
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Correct... the grid doesn't care. From what I remember... it's been almost 4 months since our consult...each Powerwall has a maximum dishcharge rate and if that rate is exceeded it will trip the system off. Charging our Tesla plus the average household usage exceeds the maximum discharge rate of one Powerwall so in order to prevent this from happening we had to add a second Powerwall.
 

Ampster

Active Member
Supporting Member
.....yet all of the videos of setups I've seen online involve a separate, external inverter.
Perhaps what you are seeing in that video is the inverter for the solar. The powerwall does not replace that, although if you go with microinverters you will not have an inverter on the wall. Some systems like the Sunpower Equinox system have the microinverters built into the panels.
 
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Perhaps what you are seeing in that video is the inverter for the solar. The powerwall does not replace that, although if you go with microinverters you will not have an inverter on the wall. Some systems like the Sunpower Equinox system have the microinverters built into the panels.
Even with Equinox, you will probably end up with an extra combiner switch-box, that also routes to the EnergyLink Monitor box (which looks like an inverter, but is not).

So technically two more boxes than a string+inverter set up, Mt combiner box has 4 breakers in it, one breaker per 12-panel micro-inverter "string": 20A +15A + 15A. Then a 15A breaker for the EnergyLink box.
 
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Reactions: Yuri_G and Ampster

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