<div dir="ltr">Hi Jason,<div><br></div><div>I think Helioscope is more suited for this analysis.</div><div>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.</div><div><br></div><div>They also have a month free trial I believe if you would like to play with it</div><div><br></div><div>Thanks</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Mar 3, 2021 at 6:40 PM Dave Tedeyan <<a href="mailto:dtedeyan@taitem.com">dtedeyan@taitem.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">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.</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Mar 3, 2021, 8:35 PM Dave Tedeyan <<a href="mailto:dtedeyan@taitem.com" target="_blank">dtedeyan@taitem.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">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. <div dir="auto"><br></div><div dir="auto">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.</div><div dir="auto"><br></div><div dir="auto">Cheers,</div><div dir="auto">Dave</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Mar 3, 2021, 6:14 PM Jason Szumlanski <<a href="mailto:jason@floridasolardesigngroup.com" rel="noreferrer" target="_blank">jason@floridasolardesigngroup.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">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. </div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Mar 3, 2021, 4:04 PM Jay <<a href="mailto:jay.peltz@gmail.com" rel="noreferrer noreferrer" target="_blank">jay.peltz@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div dir="ltr">Emphase has a white paper showing production vs module size and locations around the country.</div><div dir="ltr"><br></div><div dir="ltr">I don\u2019t know if it\u2019s more accurate than pv watts but you might check it out. </div><div dir="ltr"><br></div><div dir="ltr">Jay</div><div dir="ltr">Peltz power. </div><div dir="ltr"><br><blockquote type="cite">On Mar 3, 2021, at 12:13 PM, Jason Szumlanski <<a href="mailto:jason@floridasolardesigngroup.com" rel="noreferrer noreferrer noreferrer" target="_blank">jason@floridasolardesigngroup.com</a>> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">\ufeff<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"></div><div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">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.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">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? </div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">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.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Jason Szumlanski</div><div><div dir="ltr"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><b><div style="text-align:center"><br></div></b></div></div></div></div></div></div></div></div></div><br></div><br><img width="0" height="0" alt="" style="display: flex;" src="https://mailtrack.io/trace/mail/5eb252f6e6d870638e7a0fd58093488ac94a581b.png?u=1613865"><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Mar 2, 2021 at 10:00 AM Jason Szumlanski <<a href="mailto:jason@floridasolardesigngroup.com" rel="noreferrer noreferrer noreferrer" target="_blank">jason@floridasolardesigngroup.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">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?<div dir="auto"><br></div><div dir="auto">Jason</div></div>
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