Allen, The other inverters do not simulate the SI. The SI can be paired with a SB such that there is some degree of proportional control of the SB output power via frequancy shifts generated by the SI. Consult SMA documentation of SI operation available on-line at SMA website. Other inverters have a one step frequency shift that will cause most grid tied inverters to see a line frequecy fault, in turn causing them to go off-line until the frequecy is corrected. I guess that the folks at Magnum are not totally confident in this setup so they recommend a back-up safety system which could be either a diversi9on load or a contactor that disconnects the grid tied inverters all together. 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-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan Sindelar Sent: Friday, September 02, 2011 4:45 PM To: RE-wrenches Subject: Re: [RE-wrenches] AC Coupling Brian, Could you speak a bit more to this, please? My understanding is that the need with a string (or, I suppose, micro-) inverter and a battery-based inverter is for a way to disconnect full batteries from being overcharged when the grid is down and sell is disabled. The SMA approach is to shift frequency to reduce string inverter output. I thought that the battery-based (Outback, Magnum) approach is to use a contactor to open string inverter AC based on voltage (crude, but effective). So what I understand is that the PAE inverters shift frequency: do you mean it simulates the shift that a Sunny Island would do? And if so, why is a diversion load recommended, and how is it configured into the system? And where can we read more about how this is designed to work? Thank you, Allan Allan Sindelar <mailto:al...@positiveenergysolar.com> al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 <http://www.positiveenergysolar.com/> www.positiveenergysolar.com On 9/2/2011 4:39 PM, Brian Faley wrote: Hi Larry, Magnum MS PAE inverters do indeed shift the inverter output frequency when the battery is full in order to disconnect grid-tied inverters used in AC coupled systems. It was designed to work in conjunction with a DC diversion load - which is recommended if the system is larger than a couple panels. Regards, Brian Faley Chief Engineer Magnum Energy 2111 W Casino Rd Everett, WA 98204 425-353-8833 bfa...@magnumenergy.com
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