Powerwall Wiring

[JerryK]

I have an existing 15kw Tesla solar system and I’ve ordered 2 powerwalls. I plan on locating the powerwalls (and gateway) in the garage, which is 40’ from the circuit boxes. I’d like to pre-install most of the conduit (Schedule 40 PVC) and wiring myself to save time and money.

Based on what I’ve read it looks like I’ll need a 3-wire 10 AWG for each powerwall. That would be a total of eight 10 AWG wires (3-wire plus ground). Do I have this right?

I've installed PVC conduit before for various electrical projects, so this seems pretty basic, but there may be something I'm missing.

I would appreciate any advice.

Thank you,

Jerry

 

[wwhitney]

Get a copy of the installation manual and see what it says. There is also a communications cable between the Powerwalls and the Gateway. The fine points of whether that can be run in the same conduit as the 30A circuits are not clear to me.

I see the upside of installing the conduit runs ahead of time (as long as they comply with the rules on sizing and number of bends between pull points), but I'm not sure I see the upside of pulling the wires ahead of time. The installers will expect to do that, and I doubt you'll get a discount.

If you do pull wires, there's no need to run multiple EGCs in the same conduit. And with 4-6 current carrying conductors in one conduit, you need to derate the ampacity by 80%. But the base ampacity of 90C insulated #10 is 40A, so even after derating it's still good for 30A. So just 7 #10 copper conductors with 90C insulation (THWN-2 if any of the run is outside), (2) red, (2) white, (2) black, (1) green. If your conduit is large enough, you could add an additional 240V/120V feeder in the future, as each such circuit counts as only two current carrying conductor.

Or you could put a small panel next to the Powerwalls and just run a minimum 60A feeder to it.

Cheers, Wayne

 

[aesculus]

There is also a communications cable between the Powerwalls and the Gateway. The fine points of whether that can be run in the same conduit as the 30A circuits are not clear to me.

In this thread the poster states as long as its shielded and rated at 600v its OK to run it in the same conduit.
Remote Solar to Powerwalls

 

[BrettS]

Get a copy of the installation manual and see what it says. There is also a communications cable between the Powerwalls and the Gateway. The fine points of whether that can be run in the same conduit as the 30A circuits are not clear to me.

Tesla ran the communication cable inside the same conduit as the power cables for my installation. They ran two one inch conduits for my four powerwalls, with the power cables for two powerwalls in each conduit.

I have an existing 15kw Tesla solar system and I’ve ordered 2 powerwalls. I plan on locating the powerwalls (and gateway) in the garage, which is 40’ from the circuit boxes. I’d like to pre-install most of the conduit (Schedule 40 PVC) and wiring myself to save time and money.

You should definitely talk to the installer before you put too much effort into running your own conduit to make sure they are ok with that.

If this is a Tesla install I would be a little surprised if they lower the price for you based on you running your own conduit. Tesla doesn’t really break out the time and materials at all in the price of the system and they just have a standard “Installation” charge that’s kind of a one size fits all, whether they need to run 100 feet of conduit or 5 feet.

If you’re working with a third party installer then they might be willing to work with you and lower the price if you run your own conduit. However I can also see an installer balking at that simply because there could be an issue if you do something wrong that doesn’t meet code and then the system winds up failing the inspection. At that point the installer may need to spend more time and effort to correct the issue or rerun the cable after you fix the conduit than they would have spent to just run the conduit themselves.

 

[wwhitney]

In this thread the poster states as long as its shielded and rated at 600v its OK to run it in the same conduit.
Remote Solar to Powerwalls

That's not generically true, but it is true in some cases. It seems to be common practice, so it is probably allowed. But I haven't yet seen the particular code sections spelled out that allow it, nor bothered to research it myself. So until that happens, I am inherently a little skeptical.

Cheers, Wayne

 

[JerryK]

This is all great information. I now have a better understanding of what to do. Thanks everyone.

 

[jjrandorin]

This is all great information. I now have a better understanding of what to do. Thanks everyone.

if you are purchasing from tesla itself, I will second the recommendation to see if they will be "ok" with using conduit and cabling they did not install, and whether that would actually save any money.

 

[buckweet1980]

I can't see Tesla giving you anything for your work. And honestly, in my experience most installers want it done their way. So if you went through all of that work, they might just toss it to the side because it's not up to their standards. In my recent install, they did all metal conduit which is the standard for electric in the industry.

So personally, I'd say let them do their thing.

 

[miimura]

I can't see Tesla giving you anything for your work. And honestly, in my experience most installers want it done their way. So if you went through all of that work, they might just toss it to the side because it's not up to their standards. In my recent install, they did all metal conduit which is the standard for electric in the industry.

So personally, I'd say let them do their thing.

I agree with this. They are unlikely to give you any discount in consideration for the work you put into it.

 

[SMAlset]

I also agree with above comments; and if Tesla is going to be responsible for connecting all your equipment, they will want to do the work themselves since they would be warrantying that work.

All of our equipment sans AC Disconnect next to our main service panel on the outside wall, was installed inside our garage. We have a medium 8.16W PV system installed along with 3 PWs (GW2 and SolarEdge 7600H inverter). Whole house backup. Two load centers were added to our interior garage wall opposite the exterior main panel wall. One has the wiring from our main panel along with GW2 and the other serves the Solar and 3 PWs. We requested our farside double-car garage interior wall installed with our 3 PWs, Inverter and GW2 (all of our white equipment mounted on a nice gray painted wall). Not sure what that distance was, but less than 40 feet; but I do know that running the wiring across the garage from the two interior load centers to the other side for all the equipment mounted there through 2-inch PVC Schedule 80 (not 40) and I believe 1-inch EMT was not easy for them in part because of the required gauge wire and the angles of the PVC.

 

[JerryK]

Thank you. Based on the comments provided I've decided to let Tesla install the conduits and wiring. Everyone made very good points and I really appreciate it.

 

[diyguy]

If you do your own work under permit and have it inspected and signed off, you’re much more likely to have it accepted by an installer. But you’d still want to arrange this with the installer in advance.

 

[BrettS]

If you do your own work under permit and have it inspected and signed off, you’re much more likely to have it accepted by an installer. But you’d still want to arrange this with the installer in advance.

That’s probably true, although I’m not sure that you can get a permit for running a conduit to a random spot on the other side of the garage. I feel like it probably needs to be part of the whole solar/powerwall permit.