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Main Panel Upgrade After Solar Panel and Powerwall Installation

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
16,805
22,231
Riverside Co. CA
IKR, most are much nicer than mine. The power prices are pretty low too, so that's really nice. Only SVP power is cheaper locally I think.

There is an edit button, you just need more posts to see it.

Yeah but it goes away after a period of time (im not sure what that is). I think the period of time allowed to edit a post depends on whether you are a supporter or not. The reason "i dont know" is because I am a volunteer mod (like most here). I know regulars are aware of that, but just throwing it out there for new people reading along wondering "wtf how come the mod doesnt know what triggers ability to edit posts?"

If you are the thread starter, the edit time is really short, like 5-10 minutes or something. If its a post in a thread, its like 30 minutes to an hour (I think).
 
Any idea how much PG&E charges to install a new distribution box? Could it be over $10K? As I mentioned, the exiting PG&E box is across the street. PG&E said that in order for my neighbor and I to share a trench, it'd only be allowed if we installed a distribution box on our side of the street. Otherwise we'd need 2 separate trenches running across the street routing to our own respective main panels.
 
Any idea how much PG&E charges to install a new distribution box? Could it be over $10K? As I mentioned, the exiting PG&E box is across the street. PG&E said that in order for my neighbor and I to share a trench, it'd only be allowed if we installed a distribution box on our side of the street. Otherwise we'd need 2 separate trenches running across the street routing to our own respective main panels.
I would be tempted to stick with two trenches...
 
I would be tempted to stick with two trenches...
Any particular reason why? Is it to avoid any issues should there be any work done that might accidentally mess with my wiring? We'd each have our own conduits.

In any case, installation of a new distribution box sounds like it can be pretty expensive to do. Plus having to wait for PG&E to complete my neighbor's design will be another ~6 months so timing might not be ideal.
 
Any particular reason why? Is it to avoid any issues should there be any work done that might accidentally mess with my wiring? We'd each have our own conduits.

In any case, installation of a new distribution box sounds like it can be pretty expensive to do. Plus having to wait for PG&E to complete my neighbor's design will be another ~6 months so timing might not be ideal.
FWIW: 1) I think that joint systems with neighbors have a way of going sideways for reasons unrelated to the joint equipment. 2) I suspect that if you coordinate the trenching, it won't be twice the cost. 3) It is one more piece of equipment to fail in your power supply, 4) Trying to put in a distribution box won't actually save you much, if any money once the dust settles.

Once you establish that your neighbor isn't on your time line, I would just go ahead and do the trenching for your needs.

All the best,

BG
 
Any idea how much PG&E charges to install a new distribution box? Could it be over $10K? As I mentioned, the exiting PG&E box is across the street. PG&E said that in order for my neighbor and I to share a trench, it'd only be allowed if we installed a distribution box on our side of the street. Otherwise we'd need 2 separate trenches running across the street routing to our own respective main panels.
I still don't understand why you need 400A.

Homes built 5 decades ago were built with 100A and they were probably 6x less efficient than even the worst stuff you can buy today. All the lightbulbs in my house being turned on today equal less power draw the lights you would have used to light up a single room back then.

You're telling me you need 200A…for an ADU that's 1/4 the size of my house built 4 decades ago? Why?
 
I still don't understand why you need 400A.

Homes built 5 decades ago were built with 100A and they were probably 6x less efficient than even the worst stuff you can buy today. All the lightbulbs in my house being turned on today equal less power draw the lights you would have used to light up a single room back then.

You're telling me you need 200A…for an ADU that's 1/4 the size of my house built 4 decades ago? Why?
I don't really need 400A but since I have to pay to trench and install conduit for my underground powerlines I figured I might as well install the 320A powerline. I'm assuming the cost to install a 320A powerline vs. a 200A powerline isn't that much more. Labor would be the same so I'm just paying for the thicker cable.

The ADU will get 100A, while the main house gets the rest. If/when I get an electric car, I'll probably install a faster charger for the main house.

I actually don't want to upgrade at all but people keep telling me 100A wouldn't be sufficient to power both the main house and ADU. I'm not sure how often both homes would be using the oven and washer/dryer at the same time or central A/C and minisplit system kicking on at the same time when there's a heat wave.
 

h2ofun

Active Member
Aug 11, 2020
4,009
1,014
auburn, ca
I still don't understand why you need 400A.

Homes built 5 decades ago were built with 100A and they were probably 6x less efficient than even the worst stuff you can buy today. All the lightbulbs in my house being turned on today equal less power draw the lights you would have used to light up a single room back then.

You're telling me you need 200A…for an ADU that's 1/4 the size of my house built 4 decades ago? Why?
My house was build 5 decades ago and it had installed a 400 amp service since it was all electric. Just the heat pump had a 100 amp breaker to it.
 
You can trench 400A service but there’s no need to take 400A into the house.

I agree completely that 100A would not be sufficient for both the house and ADU, especially if either is fully electric (no gas). Here’s how I would sequence your construction, assuming you wanted to get this done ASAP:
- upgrade house load center to 200A. Replace its main breaker with a 100A one since your current service is only rated for 100A. Run a sub panel to the ADU.
- install the solar and power wall and tell them to design and install it for 200A service. Make sure that when they do the install, they wire it for 200A service.
- whenever you finally get the new service trenched over, make sure the line from the meter to the house load center is rated for 200A. Put back the original 200A breaker into the load center.
 
Any idea how much PG&E charges to install a new distribution box? Could it be over $10K? As I mentioned, the exiting PG&E box is across the street. PG&E said that in order for my neighbor and I to share a trench, it'd only be allowed if we installed a distribution box on our side of the street. Otherwise we'd need 2 separate trenches running across the street routing to our own respective main panels.
I feel like it could be in that price range. I know that when we remodeled, we undergrounded the utilities from the pole right in front of our house, I was surprised to get a bill from PG&E for $10k just to reconnect our service. Our contractor dug and ran the lateral conduits from our new panel/meter socket across our front yard to the base of the pole, so all PG&E had to do was drop a line straight down the pole instead of diagonally down to our roof. They did cover/insulate the vertical line with a rubbery conduit strip sealed against the pole, and they did put a distribution box at the base even though we were the only one of the three houses served by our pole to have underground service.

Later when the house next door was rebuilt, they also undergrounded their service from the same distribution box. When the third house across the street remodeled, they opted to retain their service from overhead, so only us and the next door home currently use our distribution box.

We possibly did increase to 200A service (I don't recall if we were only 100A before), so part of our $10K bill may have been for upgrading our service line at the time....
 
You can trench 400A service but there’s no need to take 400A into the house.

I agree completely that 100A would not be sufficient for both the house and ADU, especially if either is fully electric (no gas). Here’s how I would sequence your construction, assuming you wanted to get this done ASAP:
- upgrade house load center to 200A. Replace its main breaker with a 100A one since your current service is only rated for 100A. Run a sub panel to the ADU.
- install the solar and power wall and tell them to design and install it for 200A service. Make sure that when they do the install, they wire it for 200A service.
- whenever you finally get the new service trenched over, make sure the line from the meter to the house load center is rated for 200A. Put back the original 200A breaker into the load center.
When I replaced my old 100A Zinsco panel a few years ago, PG&E said I had replace it with a like for like panel (so another 100A panel). So I'm not sure if I'd be able to install a larger panel when I don't have that service. In my case, I already purchased a 400A panel already but was going to install it when I upgraded my service. I also have to relocate the new panel to be 3ft from my gas. Some electricians mentioned PG&E tells me where the new trench comes in at to feed to new panel (so I can't install the new panel until they tell me)
 
PG&E said it would cost about $40k for them to do the trenching from across the street to my main panel!
Independent contractor would cost about $28k ($20k trenching + $8k PG&E fees) which is still a crazy amount to me.

I'm not sure if PG&E will need to upgrade the transformer that feeds my block. I'm assuming if they did, it'd take them a long time to do so.

Tesla said they can install the solar panels and Powerwalls from my 100A main panel. I know it's best to install solar after main panel upgrade to 400A (two 200A breakers) but that may take another year to happen. The ADU is 90% complete and the city won't sign off on final inspection until solar is installed.

If I have 100A panel, do you know if the electrical lines they install from the gateway to the solar panels and Powerwalls can handle 200A service? If I upgrade my panel later I wouldn't want to have to replace those electrical lines.

If I have 100A panel, I'm assuming they'll run a 100A electric line from the 100A main panel to the Tesla gateway. I'm hoping I'd only have to replace the electrical line from the main panel to the gateway when I upgrade to a 400A panel and not all the electrical lines after the gateway.

People must have upgraded their main panels after Tesla installed solar. How did these people handle the change? Did Tesla come back out or did they have to hire independent solar company or electrician to replace the electrical lines?
Hydraulic trenching should be much cheaper. Look into it
 

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