<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div dir="ltr"></div><div dir="ltr">Looking at it from performance ie watts, how far off does it appear to be?</div><div dir="ltr"><br></div><div dir="ltr">Jay</div><div dir="ltr"><br></div><div dir="ltr"><br></div><div dir="ltr"><br><blockquote type="cite">On Feb 10, 2026, at 2:07 PM, Dave Tedeyan via RE-wrenches <re-wrenches@lists.re-wrenches.org> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div dir="ltr"><div>Hi All, </div><div><br></div><div>I was just reviewing a site installed about 5 years ago and am finding it is not doing nearly as well as I would have expected. Most of our sites produce relatively close to our projections, but this one is pretty far off. There are 3 strings of 12 Q.PEAK DUO BLK-G6+ modules. Two strings go to a 7.7kw inverter and one string goes to a 3.8kw inverter - both of which are the -41 series SMA inverters. There are Tigo TS4-R-F rapid shutdown devices on all the modules.</div><div><br></div><div>Vmp for 12 of these panels should be about 407V at STC. At 50C (which is really hot for upstate NY), the Vmp should be around 380V. On a perfect summer day, I am seeing Vmp of around 320V. On a perfect spring day (cooler, with some power clipping, I am seeing Vmp of around 355V. And on a perfect winter day (when there was no snow) Vmp is around 365V. All three strings are pretty consistent with each other, so I don't think that there are specific installation issues with any panels, unless we managed to forget to wire in two panels in all three strings which is extremely unlikely.</div><div><br></div><div>So, I can only think of two things that might be at play here:</div><div>1. Maybe these modules are just crap, and are not at all performing to spec.</div><div>2. Maybe the Tigo devices are causing issues. </div><div><br></div><div>Has anyone out there experienced production issues like this? Everything appears normal, it is on an open rooftop, and there are not things like partial shading, weeds, bird poop, or other soiling affecting the modules. I don't have another site with the same modules that also has good monitoring data, but maybe some of you do!</div><div><br></div><div>Thanks for the consideration!</div><div>Cheers, </div><div>Dave</div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><br style="color:rgb(34,34,34)"><div dir="ltr" style="color:rgb(34,34,34)"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"></div></div></div><div dir="ltr"><table cellpadding="0" cellspacing="0" style="border-spacing:0px;border-collapse:collapse;color:rgb(68,68,68);width:525px;font-size:11pt;font-family:Arial,sans-serif"><tbody><tr><td width="125" valign="top" rowspan="6" style="padding:0px 10px 0px 0px;font-size:10pt;border-right:1px solid rgb(236,189,0);width:125px;vertical-align:top"><img style="color:rgb(32,33,36);font-family:Arial,Helvetica,sans-serif;font-size:small" width="96" height="95" src="https://ci3.googleusercontent.com/mail-sig/AIorK4zoZ4JdaR79CFcLmy74s-VRVaVovMEuRmw5pzk3XBT09h8ZNlFbMgJ4yHW2Uxf91_2codJGB4DALADN" data-unique-identifier=""></td><td style="padding:0px 0px 0px 10px"><table cellpadding="0" cellspacing="0" style="border-spacing:0px;border-collapse:collapse;background-color:transparent"><tbody><tr><td valign="top" style="padding:0px 0px 5px 10px;width:400px;vertical-align:top"><span style="color:rgb(236,189,0);font-size:11pt;font-weight:700">Dave Tedeyan, P.E.<br></span><span style="font-size:11pt;font-weight:700"><font color="#ecbd00">Owner | Sungineer Solar</font><br></span></td></tr><tr><td valign="top" style="padding:5px 0px 5px 10px;font-size:10pt;vertical-align:top;line-height:17px"><span style="color:rgb(236,189,0)"><span style="font-weight:700">p: </span></span><span style="font-size:10pt;color:rgb(0,0,0)">he | him | his</span><span style="color:rgb(236,189,0)"><span style="font-weight:700"><br>a: </span></span><span style="font-size:10pt;color:rgb(0,0,0)">1653 Slaterville Rd.</span> <span style="font-size:10pt;color:rgb(0,0,0)">| Ithaca, NY 14850</span><br><span style="color:rgb(236,189,0)"><span style="font-weight:700">w:</span></span><a href="http://www.sungineersolar.com/" rel="noopener" style="color:rgb(51,122,183);background-color:transparent" target="_blank"><span style="font-size:10pt;color:rgb(0,0,0)"> www.sungineersolar.com</span></a><br><span style="color:rgb(236,189,0)"><span style="font-weight:700">c:</span></span><span style="font-size:10pt;color:rgb(0,0,0)"> (607) 270-0370</span></td></tr></tbody></table></td></tr></tbody></table></div></div></div></div></div></div>
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