I didn't say it's an incorrect use. Please reread what I wrote. I agree it's one of its biggest advantages.
But in Africa, once it fails it may be very hard to find a technician who can determine what controller to replace it with if the SB50 fails. (They aren't serviceable in the field, but must be shipped to Blue Sky, I believe.) Maybe Phocos is widely available in Senegal, in which case it's a better choice. When the RVPP SB came out in late 1998, we didn't have many odd-cell-count modules, so that wasn't recognized as an advantage. And those controllers that sweep over a wide range to determine MPPT, such as the MX60, are much better suited to matching odd-cell-count modules than the SB, which has a limited adjustable boost range relative to battery voltage. Allan Sindelar al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com _____ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Wind-sun.com Sent: Tuesday, June 30, 2009 11:21 AM To: RE-wrenches Subject: Re: [RE-wrenches] Solar Boost Controller in Senegal Not sure why you think that cell matching is an incorrect use for MPPT. That is one of it's biggest advantages. ............................................................................ ...................... Northern Arizona Wind & Sun - Electricity From The Sun Since 1979 Solar Discussion Forum: http://www.wind-sun.com/ForumVB/ ............................................................................ ...................... ----- Original Message ----- From: Allan Sindelar <mailto:al...@positiveenergysolar.com> To: 'RE-wrenches' <mailto:re-wrenches@lists.re-wrenches.org> Cc: jo...@earthwalk.com Sent: Tuesday, June 30, 2009 10:01 AM Subject: Re: [RE-wrenches] Solar Boost Controller in Senegal Walt, 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.
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