[RE-wrenches] Inverters Maximum Input Ratings

Jason Szumlanski jason at fafcosolar.com
Tue Aug 26 03:29:47 PDT 2014


Interesting comment - we have thousands of M215's in service with an
extremely low failure rate (maybe 1 or 2). I have purposefully not started
installing M250's because the M215 seems like a low risk and I'm waiting
for good pricing on 280W, 60 cell modules. It's not exactly off-topic, as
there seems to be evidence that a higher module rating/inverter rating
ratio results in more energy harvest, presumably in part due to inverter
efficiency increasing as the input power increases. That's why I have been
reluctant to put 250-265W modules on the M250.


Jason Szumlanski

​Fafco Solar

​



On Tue, Aug 26, 2014 at 1:59 AM, Jerry Shafer <jerrysgarage01 at gmail.com>
wrote:

> 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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