<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">Mac Lewis was nice enough to run some Helioscope simulations for me (thank you, Mac). The numbers were almost identical to PVWATTS in that per kW, you get about 1% less energy yield with a 420W/IQ7A than a 385W/IQ7+ when operating at 208Vac. Given that the IQ7A is more costly, and presumably the higher powered modules will start off at a higher $/w cost, it probably doesn't make sense to use the 420W/IQ7A on a commercial building, but the energy yield differences were much smaller than I anticipated. On the flip side, higher energy density is an obvious choice if maximum utilization of the roof is more important than a small difference in ROI.</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">I'm still trying to get a definitive reason that Enphase lists the IQ7+ at a constant 290W for 240/208 (1.21A/1.39A output currents, respectively), but the IQ7A is rated at 349W for 240V and 290W for 208V (1.45A current for both output voltages).</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</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"><br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><table border="0" cellpadding="0" cellspacing="0" style="font-family:"helvetica neue",helvetica,arial,sans-serif"><tbody><tr><td rowspan="2"><br></td><td rowspan="2"></td></tr></tbody></table><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" class="mailtrack-img" alt="" style="display:flex" src="https://mailtrack.io/trace/mail/93208237424c71a0f1d7ff86bad1bd970fe21f6d.png?u=1613865"><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Mar 3, 2021 at 8:36 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">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" 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" 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" target="_blank">jason@floridasolardesigngroup.com</a>> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">\ufeff<div dir="ltr"><div style="font-family:arial,helvetica,sans-serif"></div><div dir="ltr"><div 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 style="font-family:arial,helvetica,sans-serif"><br></div><div 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 style="font-family:arial,helvetica,sans-serif"><br></div><div 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 style="font-family:arial,helvetica,sans-serif"><br></div><div 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="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7"><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" 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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