Question regarding a sub panel

[Zer0t]

I need to run a sub panel to a detached structure for my pool and for my charging station. I have a pending solar order (permits are done waiting for utility). The battery walls will go in this structure so I am assuming the inverters will go there as well. There will be a 50 trench back to my house to connect to my main panel in my basement.

My question is this: can I run a panel now so that I can get my car charger installed and will it effect my solar design? I believe I am getting Gateway 1 so I believe there is no ability to connect directly to the gateways to get power to the sub panel so it must be run from the main panel. I really need to get the sub panel soon (pool and charger) but don't want to mess up my pending solar install.

I'd appreciate one of you knowledgable folks chiming in here and I can provide whatever additional information necessary to help get to an answer. My MS chargers at at 4-5 mph but my MY charges much slower. I have an electrician to do this work that I found on Tesla's website.

Cheers and thanks in advance,

Desperate for power.

 

[BrettS]

I’m having a hard time picturing exactly how everything is set up. So right now your meter and main panel and everything are on/in your house, correct? Then you have a separate structure where you will put the batteries as well as this new subpanel? Will you want the sub panel to be backed up by the powerwalls? Do you have the electrical diagrams from Tesla that show where they will be putting everything? Assuming that your solar panels are on the house, then I would assume that the inverters would go on the house as well, but I don’t know for sure about that.

 

[BrettS]

So after I saw your comment in my other thread I think I kind of understand what you are saying. If the gateway is on the separate structure you want to know if the sub panel can connect directly to the gateway so the power doesn’t have to go from the gateway in the separate structure, through the 50 foot trench to the main panel, then back through the 50 foot trench to the subpanel in the separate structure.

I don’t believe that there are additional lugs where you could connect a second backed up loads subpanel to the gateway. Additionally there would be a concern about power draw with that. The gateway can only handle 200A, so if you had two panels connected they would have to add up to less than 200A since the gateway doesn’t have an internal circuit breaker.

One thing that might work would be to put a 200A backed up loads panel in your subpanel and have that fed by the gateway, then turn the main panel in your house into a subpanel on that new panel. However, doing that would very much affect your solar install as that would need to be included in the electrical drawings for the permits and such. Even if there was a way to connect that subpanel directly to the gateway it would affect your solar install as that would also need to be included in the drawings.

Your best bet is probably to go to Tesla and explain what you want to do and see if they can accommodate this during your solar install.

 

[Zer0t]

OK, here is the diagram. The panel and meter are in the main house. The power walls will be in the detached garage structure so I am not sure if that's where the inverters / Gateway go. I always thought that was installed near the power walls. There will be a line trenched between the main house and the detached garage. Here is the diagram from Tesla. I know the diagram says the power walls will be installed near my utility meter in this diagram but it's not the case. I spoke to them and they will be housed in the detached garage. I will call Tesla Monday as they are not in the office today.

 

[Zer0t]

Ugh, I may have a bigger problem. Tesla drew the equipment being on the outside of my house, but on the wrong side of the house with no way to get to the electrical panel from the location they chose. The basement is finished (sheetrock ceilings) and there's no way my wife is going for ripping that out and replacing it. The location on the other side doesn't have nearly the room to install of the gear thus I thought I agreed with them it would all be in the garage. If not it looks like no sun power for me just a 22kW generac and my charging station. Dang. We'll see what happens Monday.

The below doesn't even represent the configuration of where my two A/C units are and all of this is sitting on top of where my gas service is. I am assuming installing all of this electrical equipment right on top of my gas service and meter would be a no-no, but what do I know? I can't believe I didn't notice this diagram in the trenching agreement. My bad should have noticed more pages.

 

[BrettS]

That diagram is showing your powerwalls on your house (the powerwalls are labeled ESS, or Energy Storage System) , so if they agreed to put the powerwalls in the detached garage then you definitely have a redesign coming. It does seem odd that they put everything on the opposite side of the house from the panel, but they could still get from the panel to the install location with conduit going up the side of the house, into the attic, then over to the other side.

As far as the actual equipment locations, when they did my install they didn’t put things exactly where they were shown on the diagram, but they still put them on the same side of the house, maybe just 20 or 30 feet further down. So I think they do have some leeway to work around things like your AC units and the gas service and such. But I don’t think they would be able to switch the whole install to the other side of the house on install day or anything major like that.

 

[Zer0t]

Yeah @BrettS we may be going back to the drawing board. It may delay me but hopefully they can move the gear to the garage as discussed. If I have a total redesign then I’ll have them do it with the new panels.

 

[Vines]

Call a 3rd party installer before giving up and going with a dinosaur. Even better Tesla modifies the design, adds a subpanel or 2 and you are good to go. This is a totally reasonable request, but 3rd party installers are more willing to do custom than Tesla is. Tesla has to give up something with the lower prices they charge.

Looks to me like adding a subpanel and putting the car charger and powerwalls in the garage is totally reasonable, though might require an additional subpanel and second set of PVC in the trench.

 

[Zer0t]

Call a 3rd party installer before giving up and going with a dinosaur. Even better Tesla modifies the design, adds a subpanel or 2 and you are good to go. This is a totally reasonable request, but 3rd party installers are more willing to do custom than Tesla is. Tesla has to give up something with the lower prices they charge.

Looks to me like adding a subpanel and putting the car charger and powerwalls in the garage is totally reasonable, though might require an additional subpanel and second set of PVC in the trench.

I’m pretty sure I discussed it with them. Are you suggesting a third party that can install power wall or is that limited to Tesla directly? I’m really hopeful they can just modify the design. If I have to go back for permits again I’ll just start over with the newer panels.

 

[Vines]

I work for a 3rd party who does exactly that. I cannot speak to the competency of a 3rd party in your area however I am sure they exist.

Just be reasonable and ask for the modifications you need to make this work. Its a 3 Powerwall plus PV system so their costs should be covered. You may have to pay a bit extra for the additional work beyond the contract.

 

[Zer0t]

I work for a 3rd party who does exactly that. I cannot speak to the competency of a 3rd party in your area however I am sure they exist.

Just be reasonable and ask for the modifications you need to make this work. Its a 3 Powerwall plus PV system so their costs should be covered. You may have to pay a bit extra for the additional work beyond the contract.

I’m happy to pay for any additions. The biggest is trenching which is already in the contract. It’s just a matter of moving the location of the equipment and accommodating the sub panel. If I need to pay for an additional inverter or labor I would willingly do so.

 

[aesculus]

There will be a 50 trench back to my house to connect to my main panel in my basement.

My question is this: can I run a panel now so that I can get my car charger installed and will it effect my solar design?

I think what you want is OK based on what I see but you will have to run multiple conduits to/from the shed as designed. The solar (DC) will be on a separate conduit going to the inverters. The AC power for a sub panel (charger and others) in another.

So the fact that Tesla only had one conduit is wrong IMHO for what you have described you want to do. It appears to me they were only considering the DC run back to the house.

 

[miimura]

Has anybody thought about the communication lines between the Gateway and the Powerwalls? It's a wired connection that has a specific maximum length. At the very least, those lines have to go through the conduit too if the PWs are in the detached structure. Even if you put the PWs on the main house, measuring the solar production on the detached garage may be a problem too.

[Edit] The CTs can be extended to 330ft (100m) from the Gateway, so this is not a problem as long as you have a conduit path from the Gateway to the remote solar inverter.
The installation manual also discusses line impedance between the PWs and the Grid interconnection point. They recommend a maximum distance of 33ft (10m) and using oversize wiring between the Generation Panel and the Grid connection point.

 

[Zer0t]

I think what you want is OK based on what I see but you will have to run multiple conduits to/from the shed as designed. The solar (DC) will be on a separate conduit going to the inverters. The AC power for a sub panel (charger and others) in another.

So the fact that Tesla only had one conduit is wrong IMHO for what you have described you want to do. It appears to me they were only considering the DC run back to the house.

They were for certain. They won’t do the sub panel even for additional money. I was going to have someone else do that but didn’t want it to interfere with the solar install. Separately I wanted my batteries in the outer garage and not exposed on the side of the house. There will he panels on the garage, thus the need for the trench so, I though they could put all of the gear there.

 

[Vines]

Has anybody thought about the communication lines between the Gateway and the Powerwalls? It's a wired connection that has a specific maximum length. At the very least, those lines have to go through the conduit too if the PWs are in the detached structure. Even if you put the PWs on the main house, measuring the solar production on the detached garage may be a problem too.

[Edit] The CTs can be extended to 330ft (100m) from the Gateway, so this is not a problem as long as you have a conduit path from the Gateway to the remote solar inverter.
The installation manual also discusses line impedance between the PWs and the Grid interconnection point. They recommend a maximum distance of 33ft (10m) and using oversize wiring between the Generation Panel and the Grid connection point.

Line impedance is not likely to be an issue at 3 PW and assumed 200A service. Even less so a 400A service, but that's up to the installer to have checked before selling the Powerwall system.

When you do have a questionable line impedance is when you need to be very careful about long runs between the components. It seems to also affect switchover time slightly, the further the equipment is spread out. To this point we don't have any systems that are non-performing due to impedance issues, since we measure every one before hand.

Impedance is a whole topic all its own, and mostly relevant to larger systems. We have had to sell less powerwalls in several cases due to this issue. 5 PW will usually work on a 400A service but not always especially in Woodside or Portola Valley where equipment is older, and service drops to the service panel are longer. On 600A services we have installed maximum of about a dozen Powerwalls with a 2 Gateway design.

 

[wwhitney]

a dozen Powerwalls with a 2 Gateway design.

What, there's no Gateway for a Powerpack? : - )

Cheers, Wayne

 

[Vines]

What, there's no Gateway for a Powerpack? : - )

Cheers, Wayne

If it was wired with 3 phase 208v that would have been our answer I am sure.

It was quite the install in the Santa Clara Hills:

We ended up downsizing this MB from 800 to 600 due to the backfeed, it was a 60 kW system installed on 1st and 2nd story trellises and the 3rd story roof. Total actual backfeed is 260A of PV. Wish I could show off the garage 12 PW install but I don't have that permission.

 

[n8dagr8]

Glad i found this post. I'm looking to do something similar - 12.24kW system with 2-3 power walls. I don't have a ton of room by my main panel but there is plenty of space in the garage for the PWs and some perfect southern-facing, shade free real estate on our garage. If i do PV on the house and garage with the power walls in the garage, what will need to be next to the main panel (help me picture my layout, please)? We need to bury the power lines running from the house to the garage, anyway, so digging a trench is already in the plans (mentally). This all may change due to local code, etc but trying to visualize layout. Thanks!

 

[Ampster]

Do you already have a critical loads panel? Has Tesla done a plan yet?

 

[Zer0t]

If this is aimed at me I do not I wanted to back up the entirety.