[RE-wrenches] P1 micro performance

Marco Mangelsdorf marco at pvthawaii.com
Sat Mar 23 02:04:38 PDT 2013


Yes, I know that that screen shot was only a moment in time.  Here it's only
March and clipping is already taking place.  Imagine what kind of clipping
is going to take place at higher irradiance levels later in the year.  Yes,
the monitoring program cannot as of now quantify what kind of harvesting
losses would take place over time compared to an identical array using
Enphase micros.  But the principle remains unchallengeable: not allowing for
maximum kWh harvesting is plain and simple NOT the best design strategy.

 

"Some clipping is good"?  You've got to be joking.  Not being able to
harvest usable solar energy is good?  What kind of optimal design philosophy
is that?

 

As module outputs have been going up, Enphase has a vested interest in
continuing to move product with little regard for the harvestable energy
being essentially lost.  Using larger micros that reduce or eliminate that
clipping is prima facie a good thing if one cares about maximizing kWh
harvest.  As more micro products come on the product with higher outputs
than the venerable and solid M215, Enphase risks being left behind and
losing market share.  I for one find that "white paper" overly self-serving.

 

marco

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Nick Soleil
Sent: Thursday, March 21, 2013 8:04 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] P1 micro performance

 

Good points David, we are in peak season for inverters to be limiting power.


Marco, your diagram shows that the modules are only overproducing the
Enphase M215's output of 225 watts for a single 15 minute period during the
day.  That would only equate to about 3 watt-hours of lost power on a day
when the modules are producing more than 1000 watt-hours.  That tends to be
in agreement with our study, which can be viewed at;
http://enphase.com/wp-uploads/enphase.com/2011/12/Enphase_White_Paper_Module
_Rightsizing.pdf. 

 

Averaged across the entire year, this loss of power would total less than
0.1%, and would be less than 0.2% for a 265 watt module.  Keep in mind that
with degradation accounted for, you will see even less limiting in future
years.  I'd encourage Wrenches to look closely at the attached document.  It
is based upon real system production data from Enlighten compared against
actual irradiance data.

Most analysts would agree that some "clipping" is good.  You will have a
better return on your investment when your DC to AC ratio is greater than
one.  In this case, bigger is better.

 

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