200 amp meter main with a location for a pv breaker as a main disocnnect

[Zee]

Hello Gents,
I need to feed 9 KW of PV into a 200A service. Currently 200 main brkr/200 rated. With distribution.
I need at least 2p50A for PV. As we all know, 40A max allowed.

No, i cannot use a single, 32A AC rated output inverter (eg SMA SB8000US, Fronius 7500). This is due to split orientations and string sizes. Panels: 30 South and 6 East.

Service upgrade to 400A? Expensive.

Any knowledge of a 200 A meter/main panel I could have the electricain (I am just doing the pv) replace the current one with? Point would be to have a spot for the (N) pv brkr as a main disconnect brkr.

Your knowledge appreciated!

btw- this bugs me so much: if panels simply had a spot for an add'l main....the whole 120% rule would be a non-issue. And it is a big issue.

 

[GoldDigger]

Hello Gents,
I need to feed 9 KW of PV into a 200A service. Currently 200 main brkr/200 rated. With distribution.
I need at least 2p50A for PV. As we all know, 40A max allowed.

No, i cannot use a single, 32A AC rated output inverter (eg SMA SB8000US, Fronius 7500). This is due to split orientations and string sizes. Panels: 30 South and 6 East.

Service upgrade to 400A? Expensive.

Any knowledge of a 200 A meter/main panel I could have the electricain (I am just doing the pv) replace the current one with? Point would be to have a spot for the (N) pv brkr as a main disconnect brkr.

Your knowledge appreciated!

btw- this bugs me so much: if panels simply had a spot for an add'l main....the whole 120% rule would be a non-issue. And it is a big issue.

Before you go to the extreme of replacing the panel or adding another panel for a supply-side tap, take a close look at the specs for the existing panel. Many 200A panels contain a 225A bus. If that is the case for your panel, and you can document that to the AHJ, you can backfeed up to 225 x 1.20 -200 = 70A. When you say "200 rated" are you saying that you have checked and the panel does have only a 200A bus?

Or if the existing calculated load allows it, you could simply reduce the size of the main breaker.

Finally, if the two inverters you need are provided with separate breakers in a combiner panel, and those two breakers add up to less than or equal to 40A, you are allowed to use that number in the main panel calculation instead of the size of the 2p50A breaker which is now a feeder breaker rather than a branch circuit breaker.

The panel configuration you are asking about is essentially an easy way of using a supply-side tap for the PV, but I would not expect a lot of demand for that kind of configuration in combination with a load center.

 

[jaggedben]

No, i cannot use a single, 32A AC rated output inverter (eg SMA SB8000US, Fronius 7500). This is due to split orientations and string sizes. Panels: 30 South and 6 East.

How about a Power-One Uno 2.0 or 2.5, in combination with an inverter with a 22A or 20A output? That might solve your problem. I think you're going to need something like that for your string of 6, anyway.

 

[Zee]

Before you go to the extreme of replacing the panel
..............

Many 200A panels contain a 225A bus.

Finally, if the two inverters .... add up to less than or equal to 40A, you are allowed to use that number in the main panel calculation

Thanks, Golddigger.
It's a Murray. I don't think those are the "secretly" 225A rated busbar panels....But truth is: i don't know. Do you happen to know?

Yeah the two brkr.s for the two inverters don't help! Not in this case, altho i appreciate the idea, it has saved me in the past.

 

[GoldDigger]

Thanks, Golddigger.
It's a Murray. I don't think those are the "secretly" 225A rated busbar panels....But truth is: i don't know. Do you happen to know?

Yeah the two brkr.s for the two inverters don't help! Not in this case, altho i appreciate the idea, it has saved me in the past.

No, I do not happen to know, but a Google search in the forum for 225A bus may come up with some.specific references from earlier threads. Also same search in Solar forums....

 

[Zee]

How about a Power-One Uno 2.0 or 2.5, in combination with an inverter with a 22A or 20A output? That might solve your problem. I think you're going to need something like that for your string of 6, anyway.

Thanks!
The 22 or 20 A inverter you recommend would be about a 5 KW inverter. I need at least a 6.5 KW inverter for the 30 panels . (30 panels at 250 W each = 7.5 KW STC.)

 

[Zee]

In case anyone thinks of it: I do not want to downsize the 200A main brkr.
The customer uses 19,000 kwh a year.....before he got his TESLA last week, which will be charged by a (N) 2p40A brkr.

Oh, and lookee what i found on the internets:
http://w3.usa.siemens.com/us/internet-dms/btlv/residential/residential/docs_Home/SIE_FL_4SOLAR.pdf
I think i have a new favorite electrical equipment mnfctr.

 

[BillK-AZ]

Look into Eaton?s Cutler Hammer Retrofit Interior Kits to upgrade the existing panelboard/loadcenter using existing box.

There are standard and custom versions. UL Listed.

http://www.eaton.com/Eaton/Products...cuitBreakers/CHRetrofitInteriorKits/index.htm

 

[Zee]

Thanks BillK-AZ,
Could i use that in a Murray panel?

 

[GoldDigger]

Jh

In case anyone thinks of it: I do not want to downsize the 200A main brkr.
The customer uses 19,000 kwh a year.....before he got his TESLA last week, which will be charged by a (N) 2p40A brkr.

Oh, and lookee what i found on the internets:
http://w3.usa.siemens.com/us/internet-dms/btlv/residential/residential/docs_Home/SIE_FL_4SOLAR.pdf
I think i have a new favorite electrical equipment mnfctr.

Have you seen the prices yet?

Sure looks ideal for new installation or service upgrade for anyone who is planning to go RE in the future.

 

[Zee]

no idea on price. As long as I don't have to do a line side tie....i can handle some cost .
This basically has a built in "supply side busbar" for a pv breaker.
The solar circuit is limited to 60 Amps - from what i could tell.
So, not quite as great as having the full 200A available for PV.

"Sure looks ideal for new installation or service upgrade for anyone who is planning to go RE in the future."

Yes i think it is a great panel upgrade for anyone with a full panel who wants PV.

 

[jaggedben]

Thanks!
The 22 or 20 A inverter you recommend would be about a 5 KW inverter. I need at least a 6.5 KW inverter for the 30 panels . (30 panels at 250 W each = 7.5 KW STC.)

I was thinking you could put some of the 30 on the smaller inverter; Power One lets you do that. Thus maybe two strings of 6 on the smaller one, two strings of 12 on the bigger one, now you only have 6kW of panels for the bigger one.

 

[don_resqcapt19]

What about a line side connection to the service? That would permit you to connect up to 200 amps of PV power to the existing service.

 

[Zee]

Don:
Line side tie difficult/impossible Code-wise with (E) equipment.

And i hate doing that in any case.

Jben:
problem is either way i combine inverters the amps exceed 40 A.
(UNO 2.0 too small for 3 KW (2 @ 6 panels) , UNO 2.5 exceeds amps i am allowed)

PRoblem solved: i just need to get electrician to upgrade panel.

 

[tallgirl]

Have you considered either ACPV or detached microinverters, rather that futzing with which size string inverters to use?

 

[Zee]

Thansk TALLGIRL, i appreciate the tip.
I considered micros/acpv panels, but no good in this situation. Two reasons:
1. I am not mounting any sensitive electronics, 25 yr wrrty or not, on this 45 degree roof, two floors up. Once i take scaffolding down, i want a rock solid reliable system up there, where the air is thin..... I am not a mountain climber.
:jawdrop:
2. The amps would still exceed the limit of 32A.

 

[c_picard]

If a supply side tap is not possible in the (E) equipment, perhaps the utility will allow a 2-barrel lug in their meter enclosure. This is being allowed in some jurisdictions. The Siemens "solar ready" meter main is essentially the same 4 space main they have always offered. There are others out there, I'm a fan of the meter main tie-in, very neat and professional. Makes sense if an upgrade is required anyhow.

The less sexy, but still code compliant method is to tap in a new j-box between the meter and equipment. Plan D is to see if the existing equipment has a feed through lug kit available.

I guess it all depends on the $ amount scribbled on the front of the napkin.

 

[agentmoller001]

Use (2) Sunny Boy SB4000TL US with a Sub-panel

Use (2) Sunny Boy SB4000TL US with a Sub-panel

If you have 36 250 W panels at 30 V ea, use two Sunny Boy SB4000TL-US inverters and put 14 South facing panels in series to input A / inverter 1, 5 South facing panels in series to input B / inverter 1, 11 South facing panels in series to input A / inverter 2, and your 6 East facing panels in series to input B / inverter 2.
Each of these inverters has 2 MPPT inputs, hence the south array split into 3 strings.
You probably know the rest ...
... DC disconnect > Subpanel with (2) 2P20A breakers > AC Disconnect > Main 2P40A

Hope this works for you.

 

[ggunn]

If you have 36 250 W panels at 30 V ea, use two Sunny Boy SB4000TL-US inverters and put 14 South facing panels in series to input A / inverter 1, 5 South facing panels in series to input B / inverter 1, 11 South facing panels in series to input A / inverter 2, and your 6 East facing panels in series to input B / inverter 2.
Each of these inverters has 2 MPPT inputs, hence the south array split into 3 strings.
You probably know the rest ...
... DC disconnect > Subpanel with (2) 2P20A breakers > AC Disconnect > Main 2P40A

Hope this works for you.

I have not run your numbers through Sunny Design but it seems unlikely to me that even an inverter with dual MPPT channels can handle one string of 14 and another string of 5.

 

[tallgirl]

I have not run your numbers through Sunny Design but it seems unlikely to me that even an inverter with dual MPPT channels can handle one string of 14 and another string of 5.

Very likely won't -- 5 panels into anything much larger than an SB700 won't make DC volts enough to turn the inverter on, much less reach the bottom of the MPPT window.

Those "sensitive electronics" aren't all that sensitive. I walk through one of the test labs on a daily basis and there aren't a lot of electronics that can survive the testing that microinverters are put through. With string inverters you have to worry about Humidity Induced Degradation (look that one up!), which turns your entire solar array into "sensitive electronics".