[RE-wrenches] Enphase Application

Thu Apr 9 08:41:11 PDT 2009

A GFDI fault requires an EMU (Envoy) to clear the fault.  Or the 
inverter must be replaced.  There is sound reasoning behind this:

1.  UL1741 requires the GFDI to "provide an indication of the fault". 
It does not stipulate how to indicate, or where to indicate.

2.  Further, the requirement states that the GFDI "shall not be capable 
of automatic reclosure".  This means some form of human interaction is 
required to clear the fault indication to allow the inverter to restart.

3.  The inverters are mounted under the module, often up on a roof and 
inconvenient to gain access to.

While some indication of the fault at the inverter can be helpful in 
verifying the "culprit", it is impractical to rely solely on a rooftop 
annunciation.  Who wants to crawl around on a roof looking under modules 
to see an LED or listen for a buzzer?  Because the EMU and inverters 
talk to each other via powerline communications, it becomes practical to 
also annunciate the fault thru the EMU (Envoy).

Once you know there is a fault, you know the serial number of the 
offending unit, and you know the location on the roof (because you were 
so diligent at filling out the install map!), it is relatively easy to 
find the actual fault.

Two brief comments on GFDI:

1.  Micro deployments see far fewer GFDIs than string installations. 
The DC wiring is localized at each module and is not strung across the 
roof.  Far fewer opportunities for pinched wire and compromised insulation.

2.  If there is a GFDI, its' precise location is identified.  You do not 
need to search thru a string (or strings) of 10 or 12 modules to find 
the problem.

Clearing the fault from the Envoy is a simple matter of "checking a 
check box" on the Envoy webpage interface.  Certainly easier than 
climbing up on a roof and fumbling around for a button or a switch.  A 
button or a switch, by the way, costs money and is a point of failure. 
We are striving to minimize both.

So, for full functionality an Envoy is required.  By the way, it's also 
required to get the California rebate, as it is the only means of 
displaying 5% metering information as required by the CSI program.  And 
yes, you probably want to have a laptop computer with you on the job site.

All other faults (over/under voltage/frequency, anti-islanding, etc.) 
are automatically reset.  The Envoy and the Enlighten Web application 
allows you to see all faults, but only the GFDI requires human 
intervention to reset.

Any other questions, just drop me a line.  Or call our excellent 
Customer Support folks at 877 797-4743.

See Ya!

Marv
Enphase Energy
707 763-4784 x7016

Travis Creswell wrote:
> I really appreciate the responses to my questions.  Marv, can you address
> Bill L's comment that some faults could require the EnPhase EMU unit to
> clear?  That's good point about shading which isn't a problem on this roof.
> 
> Regarding the "wasted glass" and "third module" of the KC120's.  Currently
> these 3 modules charge a battery bank with only a few rarely used lights on
> it.  Is used to be more frequently used but not now so the batteries are
> spending most of their time at float thus the glass is already wasted.  The
> third module will continue to charge the same battery bank.
> 
> Best,
> Travis Creswell
> Ozark Energy Services
> 
> 
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Marv Dargatz
> Sent: Tuesday, April 07, 2009 7:32 PM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] Enphase Application
> 
> Travis,
> 
> You are exactly right.  As long as you do not exceed the max open 
> circuit voltage or short circuit current rating you're perfectly fine. 
> Even if you put 300W of module on the inverter, it will just hit power 
> limit until the irradiance declines enough to let the MPPT work again. 
> No problem.  No damage to the module or the inverter.  The "smoke 
> threshold" voltage is many volts above our stated maximum input voltage. 
>   Of course, it probably doesn't make economic sense to waste that much 
> glass.
> 
> In your case, two Kyoceras in series will work just fine.  Depending on 
> the age of the modules, soiling, etc., you'll probably have less than 
> 240W peak.  I'd guess you will seldom see the inverters hit power limit.
> 
> This configuration will have no impact on MTBF or reliability.
> 
> Do be aware that if you shade one of the two modules, you'll limit the 
> output of both modules in the series string.  No worse than a standard 
> string inverter.
> 
> We chose a Tyco CPC connector for cost, reliability, and environmental 
> reasons.  If you can find a connector that meets the demanding NEMA6 
> requirements at a better price, please let me know.  We're constantly 
> looking for ways to reduce product cost without degrading reliability.
> 
> Hope this helps.
> 
> See Ya!
> 
> Marv
> Enphase Energy
> 707 763-4784 x7016
> 
> Travis Creswell wrote:
>> Greetings Wrenches,
>>
>> I have customer with a three module array made up of 120 watt Kyocera's
> that
>> charge the battery bank underutilized of “hobby system”.
>>
>> It spends most time in float plus were adding a 5.5 kW direct grid tied
>> array that require us to move the existing array so the customer is
>> interested in putting an EnPhase inverter on two of the Kyocera 120’s.
>>
>> I’ve looked over the EnPhase specs and don’t see a reason why I can’t wire
>> two KC120’s in series and feed the EnPhase with them.  I do see them
> listing
>> it’s compatibility of up 225 watt modules but am having a hard time
> getting
>> much further.  I didn’t find a max input wattage so what happens if I put
>> 240 watts to the EnPhase?  Does the magic smoke come out on day one or
> does
>> MTBF drop from 32,895 years to 80 years?
>>
>> Even is the EnPhase's max output is 200 watts it's still more kWh/day then
>> the hobby system that spending most of it's time in float.  I can see no
>> difference between one 72 cell module and two 36 cell module in series.
>>
>> Also it looks like there is unique connector coming off the AC side of the
>> module.  How do I deal with that?
>>
>> Best and thanks in advance!
>> Travis Creswell
>> Ozark Energy Services
>>
>>  
>>
>> No virus found in this outgoing message.
>> Checked by AVG. 
>> Version: 7.5.557 / Virus Database: 270.11.43/2043 - Release Date: 4/6/2009
>> 6:22 AM
>>  
>>
>> _______________________________________________
>> List sponsored by Home Power magazine
>>
>> List Address: RE-wrenches at lists.re-wrenches.org
>>
>> Options & settings:
>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>
>> List-Archive:
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>> List rules & etiquette:
>> www.re-wrenches.org/etiquette.htm
>>
>> Check out participant bios:
>> www.members.re-wrenches.org
>>
> _______________________________________________
> List sponsored by Home Power magazine
> 
> List Address: RE-wrenches at lists.re-wrenches.org
> 
> Options & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
> 
> List-Archive:
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
> 
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
> 
> Check out participant bios:
> www.members.re-wrenches.org
> 
> No virus found in this incoming message.
> Checked by AVG. 
> Version: 7.5.557 / Virus Database: 270.11.45/2045 - Release Date: 4/7/2009
> 6:41 AM
>  
> 
> No virus found in this outgoing message.
> Checked by AVG. 
> Version: 7.5.557 / Virus Database: 270.11.47/2047 - Release Date: 4/8/2009
> 5:53 AM
>  
> 
> _______________________________________________
> List sponsored by Home Power magazine
> 
> List Address: RE-wrenches at lists.re-wrenches.org
> 
> Options & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
> 
> List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
> 
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
> 
> Check out participant bios:
> www.members.re-wrenches.org
> 