[RE-wrenches] Charge Control in AC coupled system

[Mark Dickson]

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-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at 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





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