[RE-wrenches] Enphase Application

Tue Apr 7 05:16:09 PDT 2009

Hi Travis,

These Enphase folks have (IMHO) thought out their "AC module" program at
least a wee bit better than the NKF (manufacturers of the Trace marketed
MicroSine) folks, allowing they have had a few more _years_ to do it.

There are multiple caveats on their documentation _not_ to exceed their
specifications, one of those is copied below.

***********************
WARNING: The maximum open circuit voltage of the PV module must not exceed
the specified maximum input voltage of the Enphase Microinverter. The output
voltage and current of the PV module depends on the quantity, size and
temperature of the PV cells, as well as the solar insolation on each cell.
The highest PV module output voltage occurs when the temperature of the
cells is the lowest and the module is at open circuit (not operating). The
maximum short circuit current rating of the module must be equal to or less
than the maximum input DC short circuit current rating of the
Micro-inverter. A list of compatible PV modules is maintained on the Enphase
website (www.enphaseenergy.com).
*********************
I have an interest in using the Enphase product, also, so I am in learning
mode at this point (No point in creating my own Enphase static demo from an
otherwise ~$200 (retail) serviceable piece of equipment) and I also try to
minimize the "magic smoke" releases on my watch.

You may be interested in knowing that you will have to provide either MC3 or
4 connectors from your "non-compatible/field compatible" two panel module
array to mate with the micro inverter. If I am reading their documentation
correctly, at least one of the faults of the Enphase micro inverter can
_only_ be cleared by using; yes, you guessed it, the Enphase Energy
Management Unit (EMU) an even more pricey piece of gear that incorporates
the optional(?) use of a (user supplied) computer. Too bad that version 1.0
of this box could not include some Euro design in both the overall form and
pictorial display which would make the _hundreds_ of dollars price at least
a bit more palatable. But then that would leave less room for the "new and
improved" Version 2.0 SunnyDisplay(sp?) knockoff. Your customer's "hobby
conversion" system is getting a bit pricey at this point. BTW, what is he
going to do with the third twelve volt, 120 watt module?

As you may already be aware, Enphase has inverters for nominal 24 volt
modules and a _different_ inverter for 32 volt modules as well as other
variations within these two module groups.

Travis, you do so well with the energy conversions from gas to electric,
heat load calculations, and so many other wrench related things. You might
want to check Marv Dargatz's (Enphase employee) two posts toward the end of
last month regarding MTBF before adding to the confusion.  I don't know why
Enphase has chosen to use this statistic in its ads, it is my understanding
this is a useful tool to determine what level of quality components should
go in a circuit. Obviously, there is some confusion at the wrench level and
probably even more so at the consumer level.

Regarding the unique AC connector at the inverter, you guessed right again,
Enphase has that available with another pricey "kit". Once my kit is
delivered (I've already gotten the bill for all this pricey equipment.) I
will report what that connector is and hopefully allow my fellow wrenches to
source that connector at non Enphase pricing. The only identification on the
inverter connector end is A6 (on the locking ring).

Best wishes for a productive install, for both the conventional and micro
systems. Let us know how they both went and if there is any realistically
viable way to compare the outputs.

Bill Loesch
Solar 1 - Saint Louis Solar
314 631 1094

----- Original Message ----- 
From: "Travis Creswell" <tcreswell at ozarkenergyservices.com>
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
Sent: Monday, April 06, 2009 7:51 PM
Subject: [RE-wrenches] Enphase Application

> 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
>
>
>
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