[RE-wrenches] Charge Control in AC coupled system

Kent Osterberg kent at coveoregon.com
Thu Oct 28 20:25:05 PDT 2010


Howie,

In an ac coupled system with Outback inverters you could use a diversion 
controller such as a Morningstar Tristar 60 on the dc side.  That would 
allow using an ac coupled system and a nicely controlled finish charge 
for the batteries too.  Since there is already a MX60 to do the finish 
charge in the system you are considering, a voltage controlled switch, 
like the Morningstar relay driver, could simply shut down the SB3000.

Kent Osterberg
Blue Mountain Solar


Howie Michaelson wrote:
> 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
>   



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