[RE-wrenches] Enphase IQ7A 3 phase limitations

[Will White]

Jason,

You should dig into the PVWatts help documentation. They get into pretty
good detail on how their calculations work. You might find the answer
you're looking for there.

Thanks,
Will



-- 
*Will White*
Curriculum Developer


e: will at solarenergy.org
w: www.solarenergy.org
p: 802-272-3092

NABCEP Certified PV Installation Professional
# 093006-34
Do you envision a world powered by renewable energy? Be the change
<http://solarenergy.org/donate>.

On Wed, Mar 3, 2021 at 6:14 PM Jason Szumlanski <
jason at floridasolardesigngroup.com> wrote:

> 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
>>>
>> _______________________________________________
>> List sponsored by Redwood Alliance
>>
>> List Address: RE-wrenches at lists.re-wrenches.org
>>
>> Change listserver email address & settings:
>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>
>> There are two list archives for searching. When one doesn't work, try the
>> other:
>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>>
>> List rules & etiquette:
>> http://www.re-wrenches.org/etiquette.htm
>>
>> Check out or update participant bios:
>> http://www.members.re-wrenches.org
>>
>> _______________________________________________
>> List sponsored by Redwood Alliance
>>
>> List Address: RE-wrenches at lists.re-wrenches.org
>>
>> Change listserver email address & settings:
>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>
>> There are two list archives for searching. When one doesn't work, try the
>> other:
>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>>
>> List rules & etiquette:
>> http://www.re-wrenches.org/etiquette.htm
>>
>> Check out or update participant bios:
>> http://www.members.re-wrenches.org
>>
>> _______________________________________________
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> There are two list archives for searching. When one doesn't work, try the
> other:
> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> http://www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> http://www.members.re-wrenches.org
>
>

-- 
*Will White*
Curriculum Developer


e: will at solarenergy.org
w: www.solarenergy.org
p: 802-272-3092

NABCEP Certified PV Installation Professional
# 093006-34
Do you envision a world powered by renewable energy? Be the change
<http://solarenergy.org/donate>.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches_lists.re-wrenches.org/attachments/20210304/ad00ca66/attachment.htm>