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: [email protected] [mailto:[email protected]] 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: [email protected] 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: [email protected] 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
