[RE-wrenches] Paralleling Mutlitple Inverter

2012-01-22 Thread Rich Nicol
Good Morning Wrenches, I'm wondering if anyone has an advice on preferred methods and component/panel recommendations for paralleling multiple inverters. The proposed system will utilize 4 SMA6000 inverters (100 amps) and will be a ground mounted system with inverters located outdoors in the cold

Re: [RE-wrenches] Paralleling Mutlitple Inverter

2012-01-22 Thread jay peltz
Hi Rich If there are no AC loads, only the inverters then there is no derate for the panel buss. However if you connect any other loads such as a metering device, now you have to apply the 120% rule. Jay Peltz Power On Jan 22, 2012, at 4:53 AM, Rich Nicol r...@solartechvt.com wrote:

[RE-wrenches] Paralleling Mutlitple Inverter

2012-01-22 Thread Nick Vida
That is very interesting Jay, do you have a code reference for no derate needed for your solar accumulation panel? Thanks, Nick Vida btw- Rich, thanks for Bernie Sanders.___ List sponsored by Home Power magazine List Address:

Re: [RE-wrenches] Paralleling Mutlitple Inverter

2012-01-22 Thread Mark Frye
Nick, Forgive me as I am referencing NEC 2008. But 690.64 (B) Load Side, ...and where this distribution equipment is capable of supplying multiple branch circuits, or feeders, or both...shall comply... To the extent the accumulation panel is NOT capable of supplying other circuits, then NONE

Re: [RE-wrenches] Paralleling Mutlitple Inverter

2012-01-22 Thread jay peltz
Hi Nick, I see (2011) 705.12 (d) where it talks about supplying branch circuits as the area where it changes. ie w/o branch circuits then all circuits are protected by the breakers as long as the main buss isn't exceeded by the solar input of course. But in putting in that metering device

Re: [RE-wrenches] Paralleling Multiple Inverter

2012-01-22 Thread William Miller
Rich: Here is the first consideration you might want to make: You state a value of 100 Amps for this system, which I assume is the maximum AC output at 240 VAC (25 Amps) times four inverters. The value of 25 amps per inverter is irrelevant to your design, however. You must take the 25 amps

Re: [RE-wrenches] Paralleling Multiple Inverter

2012-01-22 Thread Mark Frye
William, The SMA6000 @ 240V has an AC output rating of 25A. 4 times 25 times 1.25 equals 125 A. If the solar accumulation panel is a dedicated load center, then the load center, feeder and feeder breaker need only be rated to 125 A. If the dedicated load center is located in the same building as

Re: [RE-wrenches] Paralleling Multiple Inverter

2012-01-22 Thread William Miller
Friends: I have heard, but I have not researched myself, a provision in the code where one could dedicate a panel to be an AC combiner to collect the outputs of multiple inverters. You would not install any branch circuit breakers and thereby eliminate the need to comply with the 120% rule.

Re: [RE-wrenches] Paralleling Multiple Inverter

2012-01-22 Thread William Miller
Jay: Thanks for citing this section. I reviewed it just now (2008 version) and I noticed that it says, capable of supplying multiple branch circuits, not actually supplying branch circuits. Any energized breaker panel is capable of supplying branch circuits. Only if you size the panel

Re: [RE-wrenches] Paralleling Multiple Inverter

2012-01-22 Thread William Miller
Mark: I would respectfully disagree, based on my reading. If you have code citations that inform me otherwise, I would be very grateful to expand my knowledge. Pending hearing otherwise from you, here is what I know, based on 2008 code, and assuming load side connection (2008 citations in

Re: [RE-wrenches] Paralleling Multiple Inverter

2012-01-22 Thread Mark Frye
William, I think we have it all out on the table. Below you cite 2008 690.64 (B) (2). But the requirements of (B) (2) do not come into play if it is excluded by the provisions of 690.64 (B). And as you already pointed out, this all revolves around the interpretation of the Code vis-a-vis the

Re: [RE-wrenches] Paralleling Multiple Inverter

2012-01-22 Thread Rich Nicol
Wrenches Thanks for the detailed responses. My understanding is the same as William's that my total back feed value is based on the over current devices for each inverter which is 40 amps X 4 = 160 Amps. Where I'm having a problem is choosing a panel based in respect to considering both the

Re: [RE-wrenches] Paralleling Multiple Inverter

2012-01-22 Thread Mark Frye
Rich, If you have an archive of Wrenches email, also see thread on this subject dating on and about March 29, 2011. Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 http://www.berkeleysolar.com/ www.berkeleysolar.com _ From:

Re: [RE-wrenches] Paralleling Multiple Inverter

2012-01-22 Thread Ray Walters
RIch; I think you're exactly right on your interpretation. Mike Holt's Guide to 2011 NEC requirements for PV... has an 'author's comment' on page 305, that the 120% buss bar rule of article 705 only applies if there are loads in the panel. If all slots are filled with PV breakers, you're

Re: [RE-wrenches] Paralleling Multiple Inverter

2012-01-22 Thread William Miller
Mark: Thank you. William ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive:

[RE-wrenches] Paralleling Mutlitple Inverter

2012-01-22 Thread Nick Vida
I am a little late on this: Mark and Jay,  thanks for the code reference for the solar accumulation panel bus rating. It is too bad that adding a little 15 amp receptacle for your monitoring that draws like 7 watts is enough to incite a derate under the more optimistic school of thought.