[RE-wrenches] Inverters Maximum Input Ratings

Jason Szumlanski jason at fafcosolar.com
Mon Aug 25 16:40:34 PDT 2014


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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