[RE-wrenches] AC Coupled with Generator

[Jerry Shafer]

Ray
The Outback does not dump load it drops inverter string (s) instead
Jerry

On Mon, Aug 17, 2015 at 5:26 PM, Ray Walters <ray at solarray.com> wrote:

> 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 Engineer303 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> 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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