[RE-wrenches] Inverters Maximum Input Ratings

[Marco Mangelsdorf]

Look, guys, what’s beyond dispute is that when we size the solar array higher than the nameplate inverter output, there will be clipping that takes place….i.e., harvestable solar power that goes nowhere.  The higher that oversize percentage, the more clipping will take place.  

 

If the design choice, as noted below, is to use a 270-watt module (from a manufacturer that learned last week that a recall notice was published by the U.S. Consumer Product Safety Commission https://www.cpsc.gov/en/Recalls/2014/SolarWorld-Recalls-Solar-Systems-with-Copper-Grounding-Lugs/ ), does it make sense to use a micro inverter that has a max output of about 225 watts (M215) or 250 watts (M250) when there are micros (e.g., ABB 300) that can handle the full output of the 270 which guarantees NO clipping?

 

marco

 

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jerry Shafer
Sent: Monday, August 25, 2014 8:00 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Inverters Maximum Input Ratings

 

Why dont you use the m250 anyway as the 250's so far are more reliable then the 215 have been. A little off topic i know.

On Aug 25, 2014 1:41 PM, "Jason Szumlanski" <jason at fafcosolar.com> wrote:

I had a tough customer recently that grilled me on how we can put a 270W solar module on a 215W inverter. Fortunately, Enphase has a wonderful white paper on the subject. However, it got me thinking... Enphase has demonstrated that higher output panels in many climates (hot SW Florida included) can benefit from modules that far exceed the inverter rating, and even exceed the inverter's "recommended input" rating. Enphase has shown that 270W+ modules can show energy harvest on the M215 where it makes sense to "oversize" the module.

 

I also received a similar query from a rather uninformed plan reviewer in an area AHJ along similar lines. Fortunately I was within the "recommended input" rating on the spec sheet of 270W with a 265W module, but I wonder what would happen if I had paired the M215 with a 280W module on my plans, which are becoming readily available now in 60 cell modules with 300W modules on the near horizon. I'm pretty sure my plan would have been kicked back for exceeding the manufacturer's recommendation.

 

My question, which applies to string inverters and microinverters, is how much is too much, what would happen if you paired an array that far exceeded the rating, and how do inverter manufacturers determine the recommended and/or maximum rating of the connected module or array? Also, why do some manufacturers have a simple recommendation while others have a "maximum" rating?

 

Jason Szumlanski

​Fafco Solar​

 

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