<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Allan,<div><br></div><div>MPPT technology is for harvesting the most power possible from any voltage being produced above the battery voltage, not the difference between Voc and Vmp. Because of this, nearly every battery charging system will benefit from MPPT chargers. The climate does not matter for properly designed systems. In a hot climate (like Yuma ;) ) you want a much higher operating voltage from the PV panels. There will still be a big advantage from MPPT. There are very few situations where I would recommend a non-MPPT controller anymore.</div><div><br></div><div>Concerning Blue Sky charge controller failures, I have sold and installed over 1000 BSE products at our retail store over the years and they have the LOWEST failure of any controllers we have sold. And, the customer service is second to no one else. I understand and agree with your opinion to have serviceable equipment in remote locations. The most reliable equipment should be considered first. I also believe that a project like the one Walt is dealing with should have included spare equipment as part of sale, and, of course, it should have been designed right. </div><div><br></div><div>I had a Phocos MPPT 100/20 in a test setup for 10 months when it failed. I can't even begin to talk about Outback problems unless I take my comments to the RE-bitching list. The BSE 3048 would be a good replacement controller because it has the same footprint as the SB50 and will handle the high Voc.</div><div><br><div> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Sans'; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="font-family: Helvetica; font-size: 12px; "><div><div>Kindest Regards,</div><div><br></div><div>Larry Crutcher</div><div>Starlight Solar</div><div>(928) 941-1660</div><div>Renewable Energy Products, Service and Installation</div><div><br></div><div>Mailing Address (NO SHIPPING):</div><div>11881 S Fortuna Rd.</div><div>#210</div><div>Yuma, AZ 85367</div><div><br></div></div><div>Shipping and retail store (NO MAIL):</div><div>2998 Shari Ave </div><div>Yuma, AZ 85365</div></span></div></div></div></div></div><div><br></div></div></span><br class="Apple-interchange-newline"> </div><br><div><div>On Jun 30, 2009, at 12:01 PM, Allan Sindelar wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'Lucida Sans'; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div lang="EN-US" link="blue" vlink="blue" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="country-region"><o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="Street"><o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="PostalCode"><o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="State"><o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="address"><o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"><o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="City"><div class="Section1"><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; ">Walt,<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; ">I would also offer that in a hot climate, MPPT in general is only useful in a case where odd cell counts take the Vmp away from 24V nominal specs. That is, MPPT was originally developed to harvest the voltage headroom between Voc and Vmp, which was greatest in cold ambient temperatures. There is little benefit to MPPT in a tropical climate, unless it’s being used (incorrectly in this case) to adapt a particular module with odd cell count.<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; "><o:p> </o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; ">Walt, I would suggest that you consider pursuing replacing the Sharps with any 12Vnom or 24Vnom module commonly in use there, and then either keep the SB50 because it’s already there, or replace it with the most reliable non-MPPT PWM controller you can bring in or find in country. This maximizes the likelihood that the system can be kept in operation even if the SB50s fail (and experience says that some will in time) and the locals can’t get service or replacement product. It seems to me that the SB50 is an unnecessarily complex component for this application, and a standard PWM replacement controller will match poorly and inefficiently to the Sharps.<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; "><o:p> </o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; ">FYI, I called Earthwalk and spoke with “Joey” there. I copied him on Rick’s email, and got a read response. So Earthwalk is aware of this situation, although Joey was a computer tech, not one of the “solar experts”. If they have integrity, they’ll contact you and start making arrangements to get this resolved. Perhaps they can wire you the funds to purchase compatible modules locally?<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; "><o:p> </o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; ">I have copied Joey on this message as well.<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; "><o:p> </o:p></span></font></div><div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; ">Allan Sindelar<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" color="black" face="Times New Roman"><span style="font-size: 10pt; color: black; "><a href="mailto:Allan@positiveenergysolar.com" style="color: blue; text-decoration: underline; ">Allan@positiveenergysolar.com</a></span></font><font color="black"><span style="color: black; "><o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" color="black" face="Times New Roman"><span style="font-size: 10pt; color: black; ">NABCEP Certified Photovoltaic Installer</span></font><font color="black"><span style="color: black; "><o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" color="black" face="Times New Roman"><span style="font-size: 10pt; color: black; ">EE98J Journeyman Electrician</span></font><font color="black"><span style="color: black; "><o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; ">Positive Energy, Inc.<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; ">3201 Calle Marie<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><st1:place w:st="on"><st1:city w:st="on"><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; ">Santa Fe</span></font></st1:city><font color="black"><span style="color: black; ">,<span class="Apple-converted-space"> </span><st1:state w:st="on">New Mexico</st1:state><span class="Apple-converted-space"> </span><st1:postalcode w:st="on">87507</st1:postalcode></span></font></st1:place><font color="black"><span style="color: black; "><o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="3" color="black" face="Times New Roman"><span style="font-size: 12pt; color: black; ">505 424-1112<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" color="black" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: black; "><a href="http://www.positiveenergysolar.com" style="color: blue; text-decoration: underline; ">www.positiveenergysolar.com</a></span></font></div></div></div></o:smarttagtype></o:smarttagtype></o:smarttagtype></o:smarttagtype></o:smarttagtype></o:smarttagtype></o:smarttagtype></div></span></blockquote></div><br></div></body></html>