Hi Jason, I think Helioscope is more suited for this analysis. If you send me the location, tilt, orientation, array type (roof or ground) and modules that you'd like to compare, I can quickly model this for you. Quite easy to do.
They also have a month free trial I believe if you would like to play with it Thanks On Wed, Mar 3, 2021 at 6:40 PM Dave Tedeyan <dtede...@taitem.com> wrote: > Then just as a follow up, I looked at the SMA-41 datasheet. This shows > that it runs at it's highest efficiency when the output power / rated > power is about 0.4 to 0.6, and the only real loss in efficiency comes when > you are running at about 0.1 and below. > > On Wed, Mar 3, 2021, 8:35 PM Dave Tedeyan <dtede...@taitem.com> wrote: > >> I've never really trusted PVWatts on this. I just did a quick test using >> my location in the northeast, with all the standard values and then just >> changing the DC to AC ratio. It's telling me that a ratio of 1.5 is almost >> exactly the same as a ratio of 1, and that around 1.3 is best. You actually >> lose about 2% at 0.5 and about 8% production at a ratio of 2. >> >> So I can only conclude that either PVWatts does not have a great >> calculation, or the efficiency loss due to not running the inverter at >> rated power is worse than I assumed. >> >> Cheers, >> Dave >> >> On Wed, Mar 3, 2021, 6:14 PM Jason Szumlanski < >> ja...@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.pe...@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 < >>>> ja...@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 < >>>> ja...@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@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. 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