[RE-wrenches] Charge Control in AC coupled system

[Darryl Thayer]

Hard way, had system that was nearly equal size, it seemed when the DG Inverter exceed the battery by 50% the DG inverter would shut down and do the grid error thing.  I THINK I had frequency shift, took a while to figure it out took many emails.  If the DG inverter did not exceed half I was fine, If I connected full power input to DG it would kick out on clear days.  I have only  one experiance like this.  But I have only one system that the DG was as big as the Battery inverter.  
Darryl 



--- On Fri, 10/29/10, jay peltz <jay at asis.com> wrote:

> From: jay peltz <jay at asis.com>
> Subject: Re: [RE-wrenches] Charge Control in AC coupled system
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> Date: Friday, October 29, 2010, 12:11 PM
> Hi Darryl,
> 
> Interesting you mention is 50% rule.
> Is this true for all bi-directional inverters?
> And curious how you found out?  hard way or via
> engineer?
> 
> thanks,
> 
> jay
> 
> 
> On Oct 29, 2010, at 9:18 AM, Darryl Thayer wrote:
> 
> > The Morningstar relay driver can exercize an AC laod
> to take the heaver loads from the inverter by controlling AC
> loads as Jay mentions. 
> > 
> > BTW this works well but becareful to have the battery
> system inverter larger than the direct grid inverter
> otherwise the battery inverter will shut down the DG
> inverter when you go much beyond 50% of the battery inverter
> capacity.  
> > 
> > Darryl 
> > 
> > --- On Fri, 10/29/10, jay peltz <jay at asis.com>
> wrote:
> > 
> >> From: jay peltz <jay at asis.com>
> >> Subject: Re: [RE-wrenches] Charge Control in AC
> coupled system
> >> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> >> Date: Friday, October 29, 2010, 10:49 AM
> >> Don't forget that you can use a AC
> >> load as well for an AC coupled system.
> >> 
> >> jay
> >> peltz power
> >> 
> >> 
> >> On Oct 28, 2010, at 8:25 PM, Kent Osterberg
> wrote:
> >> 
> >>> 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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