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Benefits of third sub panel for solar and Powerwall

Ampster

Active Member
Oct 5, 2012
1,801
485
Kenwood, California
Some time ago I saw a post in which the poster had three sub panels, one for regular loads, one for critical loads and one for solar and Powerwals. I am about to submit a permit application and was wondering what the advantage was of having solar and Powerwalls on a separate sub panel. In my case adding an additional sub panel would be easy and my inverter and future Powerwalls will all be located on the same interior wall. The main panel is on the exterior wall contiguous to this wall.

In framing this issue I can see an advantage in piping to the sub panel, especially since I plan on using wire gutters above and below the sub panels. This gutter configuration will also allow the Neurio and CTs to be placed without having to extend their leads. I may have answered my own question but if anyone wants to confirm my assumptions please chime in.
 

Jays200

Member
Apr 1, 2016
601
591
Perth, Western Australia
You don't say where you're located but here's what I've done in Western Australia.

I put in a new 600x600mm main board with I think 72 poles in three rows. I have three x 3phase circuits for the car and each one takes up 7 poles. One has a four pole energy meter. I also have two sub boards for the house and shed and each one needs three poles. My solar feeds in to this board. I have a Smappee energy meter and this needs room behind for six CT clamps. My main feed is 16mm2 four core and earth and my subs are 10mm2 four core and earths.

This all takes up space and my electrician appreciated the extra room.

If you can add an extra board then go for it. Most boards end up crammed full and look like rubbish.

I even bootlace crimped mine and it's a beautiful board. Our energy dept inspector had seen nothing like it on a residential property ;)
 

AEdennis

Active Member
Jul 23, 2013
2,719
938
Some time ago I saw a post in which the poster had three sub panels, one for regular loads, one for critical loads and one for solar and Powerwals. I am about to submit a permit application and was wondering what the advantage was of having solar and Powerwalls on a separate sub panel. In my case adding an additional sub panel would be easy and my inverter and future Powerwalls will all be located on the same interior wall. The main panel is on the exterior wall contiguous to this wall.

In framing this issue I can see an advantage in piping to the sub panel, especially since I plan on using wire gutters above and below the sub panels. This gutter configuration will also allow the Neurio and CTs to be placed without having to extend their leads. I may have answered my own question but if anyone wants to confirm my assumptions please chime in.

You don't say where you're located but here's what I've done in Western Australia.
...

Looking at @Ampster club listings, I assume he's in Southern California...

I didn't design the installation for Tesla, but have the following.

1) Main with the entire house connected to a large sub for all the circuits.
2) A Sub Panel that all the solar and PWs are on. This connects to the Tesla Gateway.
3) A Sub Panel just for Solar that Tesla had to connect a meter to because Southern California Edison wants to be able to see the solar production in order to FINALLY approve PTO (My install has been going on since the first week of August 2017... Ten months ago.)

Hope that helps
 

wwhitney

Member
Nov 2, 2017
965
1,313
Berkeley, CA
Depending on the how the feeders are run, putting all the power sources into one panel may allow for economization on the size of other panels under the NEC rules in section 705.12(B).

Cheers, Wayne
 
  • Informative
Reactions: Ampster

Ampster

Active Member
Oct 5, 2012
1,801
485
Kenwood, California
Depending on the how the feeders are run, putting all the power sources into one panel may allow for economization on the size of other panels under the NEC rules in section 705.12(B)
Thanks, that is helpful as far as my understanding of NEC rules is concerned. Also since I may add some micro inverters in the future the breaker feeding that third panel would be the single disconnect required under that section.
 

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