We have done several of these systems with various inverter combinations. We used a voltage activated relay in the stone age to switch inverters between battery banks and the grid before the Trace SW came on scene. This little switch opens and closes a relay based on user adjustable set points. Just put a current carrying relay between the two inverters and use this unit to open and close it at your battery set points. You are simulating a power failure to the sell back inverter when the relay opens. Contact me off list if you need one. I have cases of them, new and in the box. Still love the old SW's, even if they did cost me a fortune. Nathan Jones Power Source Solar Springfield, MO 417-827-0738
On Thu Oct 28th, 2010 3:32 PM CDT Mark Dickson wrote: >We have done one this way and came up with a good solution that has been >working great for two years now. However, this is proprietary information, >so tough . . .! >Just kidding. . . >We used a Morningstar Relay driver to control 3 different "dump loads" that >turn on at consecutively increasing battery voltages. The fourth relay that >kicks on is one that cuts the Outback's AC power to the Sunnyboys and shuts >the solar down just in case the dump loads fail or if they are getting way >more solar than they can utilize. The dump loads that come on prior to this >are various heaters and ice melt systems. These dump loads work out great >since the customers are only there in the summer and they rely on these >heaters to keep their fancy home from freezing in the winter. > >Best regards, > >Mark Dickson, >NABCEP Certified Solar PV Installer T >Oasis Montana Inc. > > >-----Original Message----- >From: re-wrenches-boun...@lists.re-wrenches.org >[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Howie >Michaelson >Sent: Thursday, October 28, 2010 2:00 PM >To: RE-wrenches >Subject: [RE-wrenches] Charge Control in AC coupled system > >Hi All, > >I have done several AC coupled off-grid systems using Sunny Islands and >Sunny Boys, but I am now doing one with a dual stacked OB VFX3648 (with a >PSX240 on the Inverter out for load balancing) and a SB3000. There is >also an existing array that is running through an MX60. What I am >wondering about is how folks have set up AC coupled string inverters to >best utilize the solar gain while not toasting the batteries. I'm a big >fan of the tapering control offered by SMA through the frequency shift of >the SI's, but that's not available here. What relay/contactor setup have >folks found most efficient and safe? Thanks in advance, > >Howie >-- >Howie Michaelson >NABCEP Certified Solar PV InstallerT > >Sun Catcher, LLC >Renewable Energy Systems Sales and Service >VT Solar & Wind Incentive Program Partner >http://www.SunCatcherVT.com >(cell) 802-272-0004 >(home) 802-439-6096 > > > > > >_______________________________________________ >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 > > > >_______________________________________________ >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 > _______________________________________________ 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
