Would you mind providing the contact information for your electrician?
Where are you located exactly? I think my electrician would work on projects in Santa Clara County and maybe southern San Mateo and Alameda Counties. Marin, Napa, Sonoma, etc., you might need to find another electrician.
Did they install the 400A service line cable in the conduit or did PG&E do that?
I believe PG&E installed the cable.
Did your trenching contractor install the conduit?
Yes.
Here's what PG&E said:
-Who do you want to trench on your private property and install the conduit? Your contractor OR PG&E
-Who do you want to trench in franchise (public street) and install the conduit? Your contractor OR PG&E
-Who you would like to install the service wire? Your contractor OR PG&E
Sounds like I need to decide if I want to upgrade to 320A line (which uses a 3" conduit same as a 200A line) or 400A line (which uses a 4" conduit).
You know how there's an 80% rule for continuous loads? The same applies to main breakers and entire panels. So there are actually two types of "400A" service.
The type I have has a CL320 meter (I'm not 100% sure what that stands for but if I had to guess, it would be
Continuous
Load
320 (Amps). This service can provide up to 400A as long as the last 80A is non continuous. This single CL320 meter feeds two separate 200A subpanel, one for the house and one for the cars.
The other type is 400A continuous service. It can provide a constant > 320A of current for more than 3 hours. So you'd be able to charge 5 cars at the maximum J1772 specification of 80A simultaneously instead of just 4 on CL320 service (note that 320A @ 240V is about 77 kW and assuming you are paying 30¢/kWh, you're consuming about $23 worth of electricity per hour at this point!) My understanding is that 400A continuous service requires a different type of meter socket; instead of the push-in meters where all of the current runs through the meter itself, it requires a CT (current transformer) meter. The current you are using actually induces a (smaller) current through the meter, which measures it and calculates how much electricity you are actually using. I didn't really inquire about 400A continuous service so I am not sure what the difference in cost would be. If you can find out, I'd still be curious though.
PG&E mentioned people who usually get 400A service get 2 meters. If I have 400A line, can I have a 200A panel or do I have to have a 400A panel split into (2) 200A parts?
Yeah, it seems like for some reason, a lot of people are doing upgrades to 200A. I understand this if your PG&E lines are overhead and there's almost no overhead to upgrade them, but I totally don't understand why people do this if it requires trenching. I'd rather do overkill (and honestly I'd probably be just fine with 200A service at the moment, possibly still fine with it even if I had two 80A EVSEs) and not have to worry about having to ever dig a trench again. I'm sure that when the house was built, people thought it wouldn't ever need a bigger service line...
I've seen a website (can't find it anymore though) where someone added a meter by de-rating the main breaker on their existing panel, adding a second main panel, and tying both into the service line at a junction box located before both meters. That's apparently how you'd add a second meter after the fact and without doing a service line upgrade (my electrician called the photo I sent him of that setup "ugly"). The other way to do it, and what my electrician was going to do if I selected the two meter option, was to simply buy a single panel that has two separate physical meter slots. If you do a service upgrade and only want one meter, then you can get a single panel with one meter slot that feeds two main breakers of 200A each.
If Powerwall Gateway is rated at 200A then I would need 2 gateways right? Does that mean I would have 2 separate independent solar panel systems each with own battery backups? I planned on purchasing 3 Powerwalls so in this situation maybe I can install 2 Powerwalls on the main house and 1 Powerwall on the ADU. I don't know if Tesla will split the Powerwalls into 2 different systems. Let's say if I ended up splitting the meters (200A each) and If I had to install 3 Powerwall on the ADU, are there independent contractors that can relocate a Powerwall from the ADU to the main house?
Sounds like a question for Tesla. But I'd assume that you would put your Powerwalls on the main panel(s) you want to back up. So if you get 3, you can go 3/0 or 0/3 with one gateway or 2/1 or 1/2 with 2 gateways. If I were to add Powerwalls to my house, I'd probably get just one gateway for the house subpanel. I don't think charging the cars from a Powerwall is very important.