[RE-wrenches] AC Coupled with Generator

[Jerry Shafer]

I cant see this working well without some battery based inverter
Jerry
On Aug 17, 2015 10:10 AM, "Ray Walters" <ray at solarray.com> wrote:

> HI Esteemed Wrenches:
>
> I am consulting on a system I have never seen, that consists of a 6.7Kw
> Enphase roof mounted system, and 2 backup generators.  Each generator has
> an automatic 200 amp transfer switch to back up its own 200 amp panel.
> Both 200 amp panels are fed by a 400 amp service from the grid.
> The Enphase PV backfeeds a subpanel in another building which then is fed
> by a 2 pole 60 amp breaker in one of the 200 amp panels.
> Currently they are having issues with the generators kicking out because
> of the Enphase inverters.  That part I understand: you can't backfeed a
> generator, or its voltage regulation freaks out.
>
> Now we get to the fun part: they want to create a third critical load
> subpanel with loads selected from both 200 amp panels to be powered by
> batteries and an inverter.
> I am considering the Sunny Island since it makes the most sense with its
> ability to signal the Enphase inverters to shut off when the batteries are
> full.  I also see this as a partial solution to the generator issue, since
> normally the Enphase will be connected to the output side of the Sunny
> Island.  However, when the generator is used to charge, we will be back to
> directly coupling the generator output to the Enphase.
>
> Here are some possible solutions I'm considering:
> 1) Use a separate charger for the generator so that it will only feed DC
> to the batteries, and not be AC coupled.
> 2) convert the PV back to DC with charge controllers, but that would
> involve ditching and adding another conduit run between buildings.
> 3)  Put the Enphase PV on a relay that would disconnect the PV when
> charging with the generator.
> 4) Something I haven't thought of that one of you clever folks can
> suggest......
>
> As always, thanks in advance for all you responses,
>
> --
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer
> 303 505-8760
>
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