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 <[email protected]> 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 < > [email protected]> 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 < > [email protected]> 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: [email protected] > > 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/[email protected]/ > 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: [email protected] > > 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/[email protected]/ > 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 > >
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