Large Solar system on 200 amp panel

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Benny92lx

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San Diego, ca
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Apprentice journeyman Insidewiremen
Hey guys, i know this topic has been beat to death, and ive done a search to try and understand, but am still confused.

Im a little confused on sizing solar to my house. Im an industrial/commercial electrician and try to stay away from pv as its not something I enjoy doing. But, we just got into our house and well, SDGE is a bit more than Id like to pay (especially with their recent price hike)

I guess my question is, How can i supersede the rule of 120 percent (which puts me at 70 amp breaker). Id like to scale up the solar and over produce in hopes to grow into with the future in mind (car charger, building of a shop, hot tub, etc etc.) i was looking into more along the lines of 10-14 kwh system.

My dilemma im a 200 amp service, with an older 200 amp panel with a 175 amp main breaker. Im going to upgrade the panel, and was looking into a 400 amp panel, but being that the meters, from what ive seen, are different, i cant do a 200 amp service to 400 amp panelboard.

Is there any way to get around the rule and still have it code compliant while also retaining the 200 amp service (i know, i can upgrade to a 400 amp service, but i cant at this time provide a load calc that will allow the city to release the 400 amp service). Im also not sure if a service side tap is allowed in our jursidiction. And i would like to have the larger PV system accepted on the permit. Im trying to push this through now to try and get into the current net metering before it all goes to hell in the near future.

Any advice is greatly appreciated, im a bit of a dummy on interpreting the code.
 
Benny92lx said:
I guess my question is, How can i supersede the rule of 120 percent (which puts me at 70 amp breaker). Id like to scale up the solar and over produce in hopes to grow into with the future in mind (car charger, building of a shop, hot tub, etc etc.) i was looking into more along the lines of 10-14 kwh system.
Click to expand...
70 Amps at 240 Volts is a little over 16 kVA.
 
Benny92lx said:
i cant do a 200 amp service to 400 amp panelboard.
Click to expand...
Huh?
I have done a 400A panelboard with a 200A main at the top connected to a 200A service and a 150A at the bottom for feed in.
I believe most manufacturers will build you a panel like that.
Eaton and Siemens at least.
 
petersonra said:
70 Amps at 240 Volts is a little over 16 kVA.
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Shoot you are right, for some reason i thought it was around 8.
tortuga said:
Huh?
I have done a 400A panelboard with a 200A main at the top connected to a 200A service and a 150A at the bottom for feed in.
I believe most manufacturers will build you a panel like that.
Eaton and Siemens at least.
Click to expand...
Good point, I dont do any residential so im unfamiliar with their residential catalog.
 
Benny92lx said:
Hey guys, i know this topic has been beat to death, and ive done a search to try and understand, but am still confused.

Im a little confused on sizing solar to my house. Im an industrial/commercial electrician and try to stay away from pv as its not something I enjoy doing. But, we just got into our house and well, SDGE is a bit more than Id like to pay (especially with their recent price hike)

I guess my question is, How can i supersede the rule of 120 percent (which puts me at 70 amp breaker). Id like to scale up the solar and over produce in hopes to grow into with the future in mind (car charger, building of a shop, hot tub, etc etc.) i was looking into more along the lines of 10-14 kwh system.

My dilemma im a 200 amp service, with an older 200 amp panel with a 175 amp main breaker. Im going to upgrade the panel, and was looking into a 400 amp panel, but being that the meters, from what ive seen, are different, i cant do a 200 amp service to 400 amp panelboard.

Is there any way to get around the rule and still have it code compliant while also retaining the 200 amp service (i know, i can upgrade to a 400 amp service, but i cant at this time provide a load calc that will allow the city to release the 400 amp service). Im also not sure if a service side tap is allowed in our jursidiction. And i would like to have the larger PV system accepted on the permit. Im trying to push this through now to try and get into the current net metering before it all goes to hell in the near future.

Any advice is greatly appreciated, im a bit of a dummy on interpreting the code.
Click to expand...
If you have or get a 200A Eaton CH panel, its busbar is 225A. Even with a 200A MCB you would have 70A of electrical headroom.
 
tortuga said:
I have done a 400A panelboard with a 200A main at the top connected to a 200A service
Click to expand...
PG&E at least has a weird (to me) rule that you can't do that, if the panelboard has a 400A rating you have to bring a 400A service to it. Not sure if SDG&E is the same or not.

Anyway, the simple answer to the OP's question (even though it sounds like the 120% rule will work for their situation) is to put in a 200A service disconnect (no distribution), and then a 200A feeder to a subpanel with a 200A main breaker and all the distribution breakers, and to interconnect the inverters by intercepting that feeder. That allows up to 160A of inverter maximum current on a 200A service.

Cheers, Wayne
 
wwhitney said:
PG&E at least has a weird (to me) rule that you can't do that, if the panelboard has a 400A rating you have to bring a 400A service to it.
Click to expand...
Here I call PG&E Portland Gas and Electric I suspect that is not that what you mean in CA.
The POCO (Pacific corp if I recall) never looked nor asked about the panel, all they did was show up pull the meter
Then came back looked at the green tag and put in the net meter.
 
I have wired several homes, including my own with 400 amp panel boards fed from 200 amp meter/mains. The utility only cares about the size of the meter/main not what you connect after it.

Since you say you want to have capacity to add the stuff you listed will a 200 amp service even cover the loads? Why would the city care if you want a 400 amp service? You don't need to prove the current load requires it. Most new services are sized greater than the current loads.

Also you will get push back from the utility if you try to get approval for a PV system that generates more than you are currently using. You can add some future loads to the application but they have a right to reject if you add too much.

For PV sizing look at the inverter output not the PV panel output. The inverter output will be less for a properly designed system.
 
petersonra said:
70 Amps at 240 Volts is a little over 16 kVA.
Click to expand...
A 70A breaker allows a max of 80% of its rating in inverter output, therefore 56A or 13.44kW.

But point taken. I don't know why he'd really need more, especially if his figures are DC nameplate, which can usually be 1.2 times inverter output or more without losing meaningful energy production.
 
jaggedben said:
Sure it does. It's just another service disco like electrofelon said, per 230.40 Exception 3.
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How's that? I assume that with PV, an MID and ESS, you'd want your PV to power your loads and ESS during an outage. That means they'd all need to be on the same service, no? I guess I didn't state that assumption.

Cheers, Wayne
 
curt swartz said:
I have wired several homes, including my own with 400 amp panel boards fed from 200 amp meter/mains. The utility only cares about the size of the meter/main not what you connect after it.
Click to expand...
OK, sure, but if you have a 200A meter/main (no distribution), you don't need a 400A bus to interconnect the PV, you can just interconnect in the 200A feeder.

Cheers, Wayne
 
wwhitney said:
How's that? I assume that with PV, an MID and ESS, you'd want your PV to power your loads and ESS during an outage. That means they'd all need to be on the same service, no? I guess I didn't state that assumption.

Cheers, Wayne
Click to expand...
So you move the backed up loads to the MID side.

The only case it doesn't 'work' is if you want to back up all the loads, in which case there's no point in a second service disconnect. But then you can usually stick your MID and generation in between the loads panel and the service, in which case you can almost certainly use the 'sum of all breakers' rule for the service (if you have a panelboard there at all) and you don't need to qualify the loads panel under 705.
 
Not following. My comment was that "a supply side connection doesn't work for a system with an MID and ESS (and the PV behind the MID." My understanding is that an MID has to either be behind a service disconnect, or has to contain a service disconnect. Maybe that's wrong?

If it's not wrong, then if the PV is behind the MID, it's behind a service disconnect, so it's not a supply side connection. Certainly there are other ways to do it under 705.12, but wasn't my comment.

Cheers, Wayne
 
This may just be semantic. Electrofelon spoke of a 230.40 Exception 3 connection. Colloquially, since it bypasses the existing equipment, that's just as much a supply side connection as doing it per 705. Code aside, it's the same thing practically speaking, the only important difference being the presence of loads on the connection.
 
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