Service Panel Size for 19kW system

[bryankloos]

Hello All,

Trying to plan a bit here...
I'm interested in installing a 19kW grid tied system.
I have currently a 200A main service panel. I'm assuming I would need to upgrade as to not exceed the buss bar ratings in the 200A panel.
What size panel would I need to move up into for the 19kW array?
All help is appreciated.
Thanks,
Bryan

[ButchDeal]

don't need any upgrade, just need to do a line side tap.

[DanS26]

or derate the main disconnect breaker from 200A to 150A (or smaller) if a load analysis would permit.

[foo1bar]

or derate the main disconnect breaker from 200A to 150A (or smaller) if a load analysis would permit.

Can potentially go down to 150A *IF*
* It is an end-fed breaker panel and can put the solar at the opposite end.
* And the load analysis allows 150A main disconnect

Otherwise there are other options.
* the already mentioned line side tap
* replace the breaker panel with something else
* make the existing breaker panel be a sub-panel of a new main panel where the new main has a 200A for all the existing circults and a separate breaker (up to 200A) for a separate panel for the solar.

Depending on the meter location, main breaker location, solar location, POCO attitude toward line-side-taps - I think any of those could be the "best" choice for a given situation.
And all of them I'd have a qualified electrician do (and beforehand of course I'd talk to him/her about which is best for my house.)

[bryankloos]

How many amps would I need to allow room for from a 20kW or a 16kW system?
I can't derate to 150, too many circuits and load. I may be okay at 175 and with an upgraded 225 watt panel that buys me 95 amps of solar capacity. I'll call the poco today regarding line side taps.

I'd rather not go up to a 400amp panel as then I'm changing out the drop, meter socket etc.

[sensij]

It depends on the rating of the inverter(s) used, but roughly,
20000/240 = 83 * 1.25 = 104 A.
16000/240 = 67 * 1.25 = 83 A.

[bryankloos]

Interesting...
So even at 16kW, I'm going to need to use 2 50A breakers to tie into my main panel, off two inverters...
With to 20kW I'm looking at 2 60A breakers. Either way, I'm exceeding the spare 95A if I upgrade to a 225 service panel and derate to 175A.
I guess I'll call to POCO and see how they feel about line side taps.
That, or upgrade to 400A service and split to 2 200A panels keeping my current panel as is, swap out my 100A for the second 200A and have the tie in on that panel....
Seems the line side tap would be cheaper.

[foo1bar]

I'd rather not go up to a 400amp panel as then I'm changing out the drop, meter socket etc.

Your service size is separate from your main panel. (except if your POCO has more restrictive rules than NEC)

So it is quite possible to have a 200A meter and 200A service that is connected to a 200A breaker for consumption and 200A breaker for production which are in a 400A panel.

So even at 16kW, I'm going to need to use 2 50A breakers to tie into my main panel, off two inverters...

I don't think so. I don't think you can have 2 separate breakers for solar on one panel and use the 120% rule. But you could have a 100A breaker to a 100A subpanel which then is split to two 50A solar inverter circuits

[bryankloos]

OK, help me understand this...

20kW system, using 2 7600W inverters.

7600/240=31.66W*1.25=39.58A so I would then use 2 40A breakers in a 100A subpanel as an AC combiner...

Now, the combined feeds from the 100A sub would feed into the main panel through a single 80A breaker?

I'm a bit confused regarding combining the 2 inverters into one AC line to the main panel.

[foo1bar]

OK, help me understand this...

20kW system, using 2 7600W inverters.

7600/240=31.66W*1.25=39.58A so I would then use 2 40A breakers in a 100A subpanel as an AC combiner...

Now, the combined feeds from the 100A sub would feed into the main panel through a single 80A breaker?

I'm a bit confused regarding combining the 2 inverters into one AC line to the main panel.

Given 2 inverters, that's probably the way I think it'd be done.
This is something the plan creator and electrician should be looking at and helping advise you on.

[sensij]

OK, help me understand this...

20kW system, using 2 7600W inverters.

7600/240=31.66W*1.25=39.58A so I would then use 2 40A breakers in a 100A subpanel as an AC combiner...

Now, the combined feeds from the 100A sub would feed into the main panel through a single 80A breaker?

I'm a bit confused regarding combining the 2 inverters into one AC line to the main panel.

This is roughly correct. There are some details to make sure it complies, but if you talk it through with the AHJ and make sure it is designed to their liking, it should be possible. You might not actually need the AC combiner/subpanel, but it does simplify the installation (and gives you independent control of each inverter) in some ways.

[FNG AZ]

OK, help me understand this...

20kW system, using 2 7600W inverters.

7600/240=31.66W*1.25=39.58A so I would then use 2 40A breakers in a 100A subpanel as an AC combiner...

Now, the combined feeds from the 100A sub would feed into the main panel through a single 80A breaker?

I'm a bit confused regarding combining the 2 inverters into one AC line to the main panel.

You got it right. 7600 watt inverters at 240vac are rated at 32 amp continuous output. X1.25=40 amps for your breakers. Slap those in a 4 space 100 amp MLO sub panel and label it..."Notice PV combiner panel. Do not attach loads." Your POCO or AHJ will have examples for label requirements in your area. Also what material the labels need to be made out of.

[bryankloos]

Great.
This said, I'm assuming a 20kW system with 2 10,000 watt inverters needs 2 60A breakers in a sub. These then use a 125A breaker in the main service panel.
If this is correct, who has 125A of reserve buss capacity in their panel? Whats then the best way (outside of line tap) to tie in a 20kW system?

[foo1bar]

Great.
This said, I'm assuming a 20kW system with 2 10,000 watt inverters needs 2 60A breakers in a sub. These then use a 125A breaker in the main service panel.
If this is correct, who has 125A of reserve buss capacity in their panel?

Who has 20kW systems?
Most people are 3-4kW.

BTW - there are people do have that much bus capacity - a 100A of load with a 200A main panel would mean 140A available. And assuming it was a 200A service that'd be OK.
(I wouldn't expect anyone to use so much PV for that amount of load - but they'd have the capacity available)

Whats then the best way (outside of line tap) to tie in a 20kW system?

Probably a new main panel with a 400A bus with a 200A main breaker feeding the existing panel and a 125A breaker connecting the "PV Combiner panel. Do not attach loads"
This is something the plan creator and electrician should be looking at and helping advise you on.

They will be able to see your entire system (what kind of meter do you currently have? what kind of main panel do you currently have? What would it take to insert a new main panel and make the existing panel a subpanel?)


A 20kW system is a *BIG* system - you should expect fairly significant changes to be needed like a panel replacement/upgrade or line-side tap.

[DaveDE2]

OK, help me understand this...

20kW system, using 2 7600W inverters.

7600/240=31.66W*1.25=39.58A so I would then use 2 40A breakers in a 100A subpanel as an AC combiner...

Now, the combined feeds from the 100A sub would feed into the main panel through a single 80A breaker?

I'm a bit confused regarding combining the 2 inverters into one AC line to the main panel.

That's what I would do except forget the 80a breaker and tie the 100a panel output into line side taps in the main panel if you have room for them. Cheaper, eliminates redundant breakers, doesn't use your main bus bar, no main panel upgrade needed and doesn't limit you to 80 amps.