[RE-wrenches] Enphase IQ7A 3 phase limitations

[Jason Szumlanski]

I've used that document many times when clients question the ratio. I wish
I knew exactly how the PVWATTS ratio calculation worked. I know there's
information on how this is all done, but I don't really have the time or
inclination to study it. I'm wondering if someone knows how accurate It is.

On Wed, Mar 3, 2021, 4:04 PM Jay <jay.peltz at gmail.com> wrote:

> Emphase has a white paper showing production vs module size and locations
> around the country.
>
> I don’t know if it’s more accurate than pv watts but you might check it
> out.
>
> Jay
> Peltz power.
>
> On Mar 3, 2021, at 12:13 PM, Jason Szumlanski <
> jason at floridasolardesigngroup.com> wrote:
>
> 
> I'm wondering how accurate the DC to AC ratio is when using PVWATTS. I did
> a quick PVWATTS analysis at my local area using a typical commercial roof
> tilt and found that using a 420W module on an IQ7A versus a 385W module on
> an IQ7+ yields almost identical results. The 420W module has 1% less
> annual production at to the 145% ratio compared to the 132% ratio with the
> 385W module.
>
> Given that, I can't imagine why anyone would use the IQ7A versus the IQ7+
> on a 208V system. Why incur the additional cost if the AC output current is
> identical for both inverters?
>
> If PVWATTS is right, I guess it's a non-issue in my local area, but it may
> vary in other locations where clipping is more common. The heat here
> results in little clipping at a 132% ratio here, and I guess at 145% the
> morning and afternoon advantages largely outweigh the mid-day clipping
> increase.
>
> Jason Szumlanski
>
>
>
> On Tue, Mar 2, 2021 at 10:00 AM Jason Szumlanski <
> jason at floridasolardesigngroup.com> wrote:
>
>> I was surprised to learn that the IQ7A is limited to 290 W continuous at
>> 208 volts. That pretty much puts Enphase out of the running for light
>> commercial jobs with new high-powered 72 cell panels. Any thoughts on this?
>>
>> Jason
>>
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