[RE-wrenches] AC Coupled with Generator

[Ray Walters]

Yes, we're definitely planning a battery based inverter.  The real 
trouble is when the generator is charging, its AC power passes through 
to the loads and hence to the Enphase inverters.
Also I agree with the other poster about Outback being more cost 
effective.  I just took a look at their Remote Operated Circuit Breaker 
(ROCB) and this looks like a good option.
I've done dump loads before, and never found that to be an elegant 
solution.  Any other options I should be looking at?

Thanks,

R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 8/17/2015 8:36 PM, Jerry Shafer wrote:
>
> 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 
> <mailto: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 <tel:303%20505-8760>
>
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