Hi Don,
Thank you for your reply. Good idea on the single 480V inverter, but multiple subarrays at different tilts/orientations and strings lengths make that impractical unfortunately. It also seems like a good idea to use a single 3-pole breaker to prevent phase imbalance, but I thought each inverter required a dedicated breaker as per 705.12(D)(1). Thoughts? Thanks, Garrison From: [email protected] [mailto:[email protected]] Sent: Thursday, April 03, 2014 1:55 PM To: [email protected]; Garrison Riegel Subject: RE: [RE-wrenches] Three Inverters, One Disconnect? With single phase 240 each inverter output is two poles; but since you are using 277 each inverter output is between one pole and neutral, so you could indeed use a 3-pole disconnect since the neutrals are not switched. A 3-pole breaker is usually used with 3-phase systems, but since there are 3 separate inverters it is legal to use 3 single pole breakers provided you get them into separate phase poles. However, there would be a phase imbalance if one breaker tripped and the others were still sourcing current, so it's better to use a 3-pole breaker here. But rather than go to all the work of wiring 3 separate 3.6 kW inverters, why not just use the PowerOne 10.0 or 12.0 kW 3-phase inverters? This would be less expensive and would need just one conduit run for input and output. Don Barch Energy Solar -------- Original Message -------- ---------------------------------------------------------------------- Message: 1 Date: Wed, 2 Apr 2014 17:20:36 -0500 From: "Garrison Riegel" <[email protected] <mailto:[email protected]> > To: "'RE-wrenches'" <[email protected] <mailto:[email protected]> > Subject: [RE-wrenches] Three Inverters, One Disconnect? Message-ID: <[email protected] <http://solarserviceinc.com> > Content-Type: text/plain; charset="us-ascii" Hello Wrenches, On an upcoming project we are interconnecting (3) Power-One, ahem, ABB PVI 3.6 inverters to a 3Ph 277/480V service. Each inverter output is 16A at 277V, 1Ph. Is it code compliant to run the single phase output of each inverter to a single pole of a 3-pole [utility required] AC disconnect before landing at each 1-pole 20A breaker in the main panel? It would be great to avoid an inverter subpanel and 3-pole breaker in the MDP if possible. Thanks for your thoughts. Garrison Garrison Riegel Project Manager | <http://www.solarserviceinc.com <http://solarserviceinc.com> /> Solar Service Inc [p] 847-677-0950 | <mailto:[email protected]> [email protected] <mailto:[email protected]> NABCEP Certified PV Installation ProfessionalT
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