[RE-wrenches] P1 micro performance

Marco Mangelsdorf marco at pvthawaii.com
Sat Mar 23 16:31:05 PDT 2013


>From Dan at Exeltech:

Trying to explain in depth the "how and why" slightly larger PV is of benefit
to a customer is like trying to explain photovoltaic equipment to the general
public.

 

I still challenge those who believe that “some clipping is good” to make their case.  And as far as the general buying public, I’m find that people do in fact understand when you ask them the following questions: Do you, Mr./Mrs./Ms. Homeowner, want a PV system that produces as much solar kWhs for your investment as possible?  Usual response: absolutely.  If I give you the choice of PV system using a 250-watt module paired with a COMPARABLY priced 250-watt micro inverter OR that same 250-watt module with a max output ~ 224-watt micro inverter that will never under any circumstances allow that 250-watt module to put out its max rated power output, which option do you think they’ll choose?  They get that.  It doesn’t take someone with an engineering degree or 10-40 years in the field to get that simple premise.  

 

For what it’s worth, being here in the tropics in the Hawaiian islands we don’t get those bright and sunny and cold late fall/winter/early spring days that will allow for an array to put out its STC-rated power.  But seeing regular times during the day—any time of year—where the irradiance is more than 1,000 watts/sq. meter is not at all common.  

 

marco

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

 

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