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--></style></head><body lang="EN-US" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I second the microinverter option in this scenario. Since you are up against a SunPower dealer, use the microinverter features to your advantage since the E20 series module is not compatible.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I probably shouldn’t be saying that as an authorized SunPower dealer, but from a competitive standpoint, I think that’s all you’ve got. The SunPower will take up far less roof space for a given rating and in theory deliver a similar or greater kWh/$ output over the lifetime. At least, that’s the sales pitch the SunPower dealer will give.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I have a couple of Enphase systems that have different tilt with the same azimuth. The lifetime output (over one year) is nearly identical from 4:12 to virtually flat if you ignore the modules that have partial shading issues. That’s down here in Florida, however, where the sun never gets too low in the sky.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1f497d">Jason Szumlanski</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Fafco Solar</span><span style="font-size:4.0pt;font-family:"Calibri","sans-serif";color:#1f497d"></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in 0in"><p class="MsoNormal">
<b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a> [mailto:<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of </b>Kirpal Khalsa<br>
<b>Sent:</b> Wednesday, April 04, 2012 12:38 PM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] Multiple angle conundrum</span></p></div><p class="MsoNormal"> </p><p class="MsoNormal" style="margin-bottom:12.0pt">
Hilton....there are a couple ways to approach this.....There are some string inverters with multiple MPPT inputs....each different slope of roof would be installed into its own input.....the other way is to use micro inverters or other individual module optimizers....in which case you are completely free from mismatched orientation and slope constraints.....<br>
If you are looking to use a single MPPT channel string inverter you may consider splitting the arrays and having two single string inverters one for each tilt angle....That said the tilt angle difference feeding the same inverter does not have as big of a negative impact as if the sub arrays are facing different directions....<br>
good luck,<br>Kirpal Khalsa</p><div><p class="MsoNormal">On Wed, Apr 4, 2012 at 9:14 AM, Hilton Dier III <<a href="mailto:hiltondier@gmail.com">hiltondier@gmail.com</a>> wrote:</p><div><p class="MsoNormal">Wrenches,<br>
<br>I am talking with a potential client about a roof mounted PV array. The client has a reasonably large south facing roof, but it is broken up by a large (18' W x 16' H) shed dormer. The roof is 10:12 and the dormer is 6:12. I designed a layout that gave the dormer some room to avoid shading. The client was disappointed by how much wattage I could get on his roof. I pointed out that installing modules in the shade of the dormer was a bad idea.<br>
<br>He is also talking to another installer. The other installer proposed installing part of the array on the 10:12 roof and part on the 6:12 dormer. The client had already asked me about that and I gave him a rudimentary explanation of maximum power point tracking and the inefficiency of such an arrangement. He asked them about that and their guy said "No big deal." He is still considering the two-angle scenario.<br>
<br>So, how much efficiency will he lose by going with two angles? It seems like the ultimate MPPT design error to me, but I don't have a number for him to make my case. I suppose it all comes down to cents per delivered kWh in the end, but two different roof angles seems the the wrong way to go. I'd like to be able to give him a definitive idea of what he would be sacrificing with that scenario.<br>
<br>Side note: The other installer is using the new Sunpower E20 modules. They seem to be available only from the manufacturer. Anybody have a source? Has anybody used them yet? Do they live up to the hype?<br><br>Many thanks,<br>
<br>Hilton<span style="color:#888888"><br><br><span class="hoenzb"></span></span></p><pre><span style="color:#888888">-- </span></pre><pre><span style="color:#888888">Hilton Dier III</span></pre><pre><span style="color:#888888">Renewable Energy Design</span></pre>
<pre><span style="color:#888888">Partner, Solar Gain LLC</span></pre><pre><span style="color:#888888">453 East Hill Rd.</span></pre><pre><span style="color:#888888">Middlesex, VT 05602</span></pre></div><p class="MsoNormal" style="margin-bottom:12.0pt">
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