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<pre>Darryl<br> The solar backfeed is about 85A, the existing 3-phase panel is about 300A and <br>drives 4 AC units and parking lights and the existing split-phase panel is about <br>200A and drives office equipment. I think I'd rather drive the 20kW directly to <br>the three phase to alleviate the AC loads than the smaller split-phase loads. Also, <br>I'm going by an article I read saying you should try not to unbalance a 3-phase <br>by more than about 6kW. The transformer might be able to handle it, but the utility<br>has not been very cooperative about providing me with specifications.<br><br> I'm not sure I completely followed your second comment. It sounds like a lot <br>of switches, though. I'm leaning towards Jeff Oldham's advice and just integrating <br>the 10A of wind at the solar AC sub-panel. It is plenty big enough and won't <br>drive up the cost.<br><br>Thanks to you and Jeff for taking time to offer suggestions.<br><br>Best Regards,<br>John Wadley<br><br><br>________________________________<br>From: <b>Darryl Thayer</b> <a href="mailto:re-wrenches%40lists.re-wrenches.org?Subject=Re%3A%20%5BRE-wrenches%5D%20One%20renewable%20disconnect.&In-Reply-To=%3C788360.6495.qm%40web39320.mail.mud.yahoo.com%3E" title="[RE-wrenches] One renewable disconnect.">daryl_solar at yahoo.com<br></a>To: RE-wrenches <<a href="http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org">re-wrenches at lists.re-wrenches.org</a>><br>Sent: <i>Wed Mar 2 15:59:20 PST 2011</i><br>Subject: [RE-wrenches] One renewable disconnect.<br><br><br>I hope i do not muddy the water here. if you have 3 phase delta, usually the <br>single phase transformer is larger, can you do the solar in split phase? <br><br><br>Also staying with the 3 phase, why not use a three pole service rated switch to <br>Line side tap, and use two poles for the single phase and the third pole for the <br>high leg. After the 3 pole switch, use a 2 pole switch for the wind turbine <br>(breaker in a box) , and a three pole sw in a box for the 3 phase solar. . <br><br><br><br><br><br>________________________________<br>From: John Wadley <<a href="http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org">wadleyjk at hotmail.com</a>><br>To: RE-wrenches <<a href="http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org">re-wrenches at lists.re-wrenches.org</a>><br>Sent: Wed, March 2, 2011 3:36:19 PM<br>Subject: [RE-wrenches] One renewable disconnect.<br><br>Wrenches,<br> I am designing a system with both wind and solar backfeed and I'm having <br>an issue with the utility. They say we need to have a single renewable <br>disconnect switch before the grid backfeed. The solar is designed to backfeed <br>3-phase through a meter, then a fused AC disconnect to the line-side to avoid <br>upsizing the MDP. The wind inverter output is 120/240V split-phase (10A) which <br>I had planned to do load-side backfeed through a wind meter with a seperate AC <br>disconnect since it was so small. To meet the single renewable disconnect <br>requirement, I'm thinking I may need to backfeed the wind on the load-side to <br>one of the three phases. I guess my question is can I use a single 5 pole fused <br>AC disconnect to control both with one switch handle or is that an NEC violation <br>wrt to merging separate systems within the same conduit? Or, should I keep them <br>in separate switch boxes with some kind of gang handle? I have a 3-phase <br>aggregation panel for the solar inverters (6 total, 2 per phase, 240 delta), but <br>if I integrate the wind there in order to simplify the AC disconnect issue, the <br>solar meter will register both solar and wind production. What is the best <br>practice in this situation?<br><br>Thanks,<br>John Wadley, MSEE, PE<br>NABCEP Certified Solar PV Installer (TM)<br>Wadley Engineering<br>214-557-3841<br><br></pre> </body>
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