690.15, second paragraph supports Drake's method: "A single disconnecting means in accordance with 690.17 shall be permitted for the combined ac output of one or more inverters or ac modules in an interactive system."
690.17 says the disconnecting means can be a switch or circuit breaker. This seems workable, with a couple caveats... The inverter manufacturer directions might specify an individual branch circuit, and you would need to use the larger size wire between the AC combiner box to the fused AC disconnect at each inverter, so you would need to choose disconnects with big enough terminals. Anyone see any other issues with this idea? -Hans ________________________________ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Drake Chamberlin Sent: Wednesday, January 13, 2010 9:59 AM To: RE-wrenches Subject: Re: [RE-wrenches] Solar accumulation panel P.S. In many cases it would be necessary to use a fused AC disconnect to stay within the inverter manufacturer's specifications. At 12:53 PM 1/13/2010, you wrote: Here is a wild idea. If you look at the Enphase inverter systems, several inverters connect together in parallel before going to an overcurrent device. In all cases, the point of connection to a utility system must be at a dedicated breaker. If there were multiple string inverters that would connect to one breaker, why not just use a junction box, instead of a combiner panel? You could put in an AC disconnect for each inverter, if it didn't come with one. The wiring would need to be sized for the combined output of the multiple inverters, which in many cases wouldn't be an issue. Drake Drake Chamberlin Athens Electric OH License 44810 CO License 3773 NABCEP TM Certified PV Installer Office - 740-448-7328 Mobile - 740-856-9648 _______________________________________________ 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: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org