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</o:shapelayout></xml><![endif]--></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'>Allan,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Just to add to Larry’s post, a 100W “12V nominal’ module would put out about 5.9A, assuming that it’s really a 100W module and has a Vmp of 17VDC. So 12 of them should be about 70-71A. The C-40 is not MPPT, so there is no amperage boost.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Luckily, the C-40 is actually rated for a max input of 63A (40A x 1.56 = 62.4A). Whoever designed that unit really did their homework (I can’t say the same for the C-60). Assuming less than stellar DYI wiring and installation, as Larry suggested, may just have saved that unit from overload. I wonder what the wiring looks like at this point, since it’s likely that he doesn’t have the correct overcurrent protection device installed, if he has any OPD at all.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Sometimes, two wrongs do make a right…sort of.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Keeping the system at 12V and adding a second C-40 would be the cheapest alternative, but going to 24V would of course be better.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Funny you should mention that “7000W 12V” inverter. I just received a spec sheet for a “5000W with 10,000W surge” 12V inverter (from China) that a potential customer wants to get for use in third-world counties. Even at 5000W, that’s over 400A at 12V, and certainly would be a higher amperage if the battery wasn’t large enough to keep it’s voltage up with a load like that. It’s also more than 4/0 cable can safely handle. Lots of hokum still out there. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Brian Teitelbaum<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>AEE Solar<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><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"'> re-wrenches-bounces@lists.re-wrenches.org [mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Larry Crutcher, Starlight Solar Power Systems<br><b>Sent:</b> Wednesday, October 24, 2012 3:11 PM<br><b>To:</b> Allan@positiveenergysolar.com; RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] C-40 question<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Allan, <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>12 100 watt modules are more likely to be about 60-70 amps. With all the losses involved in a poorly designed DIY system (like most of them), I would expect to see more than 25% power loss. Perhaps that is why the controller lasted.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>There is no current limiter in the C series controllers. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Great advice about upping to 24 volt. I can only imagine how many strings of batteries they must have at 12 volts. Egads!<o:p></o:p></p><div><div><div><div><div><p class=MsoNormal><span style='font-size:13.5pt;font-family:"Helvetica","sans-serif";color:black'><br>Larry Crutcher<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:13.5pt;font-family:"Helvetica","sans-serif";color:black'>Starlight Solar Power Systems<o:p></o:p></span></p></div></div><div><p class=MsoNormal><span style='font-size:13.5pt;font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div></div></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Oct 24, 2012, at 2:45 PM, Allan Sindelar wrote:<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Wrenches,<br>Sometimes I encounter a situation that I have never encountered, simply because it's so far beyond normal limits that I would never try it to find out what would happen. Here's one.<br><br>A did-it-myself customer called me for batteries for his system. I learned he has a 12V system, with twelve 100 watt PV modules and a Xantrex C-40 controller. He has been using this for five years.<br><br>Twelve 100W modules is around 80-90 amps - double or more the C-40's capacity. Assuming that what he told was accurate, why is the C-40 still working? Is it current-limited internally?<br><br>By the way, since he had a 7,000 watt (yeah, right) 12V inverter from a truck stop, I encouraged him to buy a 24V inverter and rewire everything to 24V; then his C-40 would (just) work.<br><br>Thanks, Allan<o:p></o:p></p><div><p class=MsoNormal>-- <br><b>Allan Sindelar</b><br><span style='font-size:10.0pt'><a href="mailto:Allan@positiveenergysolar.com"><span style='color:#000099'>Allan@positiveenergysolar.com</span></a></span><br><span style='font-size:10.0pt'>NABCEP Certified Photovoltaic Installer<br>NABCEP Certified Technical Sales Professional<br>New Mexico EE98J Journeyman Electrician<br>Founder and Chief Technology Officer<br><b>Positive Energy, Inc.</b><br>3209 Richards Lane (note new address)<br>Santa Fe, New Mexico 87507<br><b>505 424-1112</b><br><a href="http://www.positiveenergysolar.com/" target="_blank">www.positiveenergysolar.com</a></span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;margin-right:722.25pt;mso-margin-bottom-alt:auto'><o:p> </o:p></p></div></div></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>