<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">If the SB50 is like other Solar Boost products, there is a zener diode on the PV input that will open if the voltage exceeds the Voc maximum. The controller will not "burn up" or be fried but you will have to replace the diode. Why it has not happened yet on a cool morning is a mystery to me.<div><br></div><div>There is an adjustable MPPT pot for tweaking the MPP of the module(s) right next to the battery pos. terminal. Since the Voc is so high with the modules in series, you may want to adjust it. With the battery at a low SoC, tweak this pot slowly for highest current output. Make sure the MPPT LED stays lit while you adjust it.</div><div><br></div><div>"Is it a dangerous way to design a system?" Not really but it was an ignorant person that did this. If it will get cooler as you say, there is a good chance the zener will open and the controller will stop functioning. The Vmp is too low to operate the panels in parallel due to your temperature. You may need to purchase a different controller that will handle the high Voc.<div><div><br><div apple-content-edited="true"> <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 26, 2009, at 5:22 PM, Walt Ratterman 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="purple"><div class="Section1"><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Hello,<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">I am in a very remote part of Senegal, (near the Guinea and Mali borders…) and I have come across some prefabricated “plug and play” American made systems installed for educational institutions.<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">The systems use two Sharp panels that are 220Watts, 33.6 Voc, 29.2 Vmp, wired in series, using #10AWG home run wire from the panels back to the charge controller.<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Charge Controller is a Solar Boost 50. <o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Batteries are Dekka AGM – two strings of 250AH, 12V batteries. (four batteries total).<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">My specific question is about the controller. This is a 24V in / 24V out charge controller with MPPT. I have not used this before, so I am not familiar with the details of operation.<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">The data sheet that I downloaded says that the maximum open circuit voltage is 57 VDC. But, this system is hitting the charge controller with two panels of 33.6 VDC wired in series for 73.2VDC. So, why is the controller not fried, or what am I seeing wrong here. I suppose with the panel temperature being elevated maybe 35 degrees above 25 degrees and a resulting 17.5% loss, coupled with some voltage drop, the system may actually be seeing less than the 57 volts. <o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">But…..isnt this a dangerous way to design a system? (it will get cooler here ….)<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Or am I missing something?<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">What would be the appropriate application here….<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Sorry, I cant do a lot of internet research from here – limited download capability on the satellite….<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Thanks!!<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Walt<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><b><span style="font-size: 10pt; font-family: Arial, sans-serif; ">Walt Ratterman<o:p></o:p></span></b></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><b><span style="font-size: 10pt; font-family: Arial, sans-serif; ">SunEnergy Power International</span></b><b><span style="font-size: 10pt; font-family: 'Times New Roman', serif; "><o:p></o:p></span></b></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><b><span style="font-size: 10pt; font-family: 'Times New Roman', serif; "><o:p> </o:p></span></b></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 8pt; font-family: Arial, sans-serif; ">11 Laurel Lane South Washougal, WA 98671<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 8pt; font-family: Arial, sans-serif; ">(360)-837-3680 ▪ fax (360)-837-1315 ▪ Skype Walt-Mobile<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 8pt; font-family: Arial, sans-serif; "><a href="mailto:wratterman@SunEPI.org" style="color: blue; text-decoration: underline; ">wratterman@SunEPI.org</a> <span class="Apple-converted-space"> </span></span><span style="font-size: 10pt; font-family: Arial, sans-serif; "> </span><span style="font-size: 8pt; font-family: Arial, sans-serif; ">▪ <span class="Apple-converted-space"> </span><a href="http://www.sunepi.org/" style="color: blue; text-decoration: underline; ">www.SunEPI.org</a><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div></div><br><br>__________ Information from ESET NOD32 Antivirus, version of virus signature database 4193 (20090626) __________<br><br>The message was checked by ESET NOD32 Antivirus.<br><br><a href="http://www.eset.com" style="color: blue; text-decoration: underline; ">http://www.eset.com</a><br>_______________________________________________<br>List sponsored by Home Power magazine<br><br>List Address:<span class="Apple-converted-space"> </span><a href="mailto:RE-wrenches@lists.re-wrenches.org" style="color: blue; text-decoration: underline; ">RE-wrenches@lists.re-wrenches.org</a><br><br>Options & settings:<br><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" style="color: blue; text-decoration: underline; ">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a><br><br>List-Archive:<span class="Apple-converted-space"> </span><a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org" style="color: blue; text-decoration: underline; ">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><br><br>List rules & etiquette:<br><a href="http://www.re-wrenches.org/etiquette.htm" style="color: blue; text-decoration: underline; ">www.re-wrenches.org/etiquette.htm</a><br><br>Check out participant bios:<br><a href="http://www.members.re-wrenches.org" style="color: blue; text-decoration: underline; ">www.members.re-wrenches.org</a><br><br></div></span></blockquote></div><br></div></div></div></body></html>