I believe the issue we had has to do with using the Sanyo high voltage PV module. As Kent points out, we were operating the controller at the design limit. I don't believe it is suited to do that as we have other Morningstar MPPT controllers working fine for several years now with lower voltage PV modules. BTW, the MPPT failures were in systems that we designed and installed using the Sanyo's.
The main reason we started using this controller is for 12 volt systems with a single high voltage module. We use other controllers when the Voc is less than 40 volts. Warren, are any of the 200 units you sold last year used with a 200 watt Sanyo other high voltage PV module(s)? Larry ----- Original Message ----- From: Warren Lauzon To: RE-wrenches Sent: Monday, January 24, 2011 11:05 AM Subject: Re: [RE-wrenches] 10A Charge / load controller All controllers have failures – most commonly due to user/installer errors. Of all the controllers we sell, Morningstar have been by far the most trouble free and has the best no-hassle warranty. We have probably sold/installed around 100 to 200 of the SS-MPPT-15 controllers over the past year or so, and have seen almost zero problems that were not caused by a bad installation of some sort. Just on a side note, of all the controllers of all brands we have sold over the past decade, probably 3/4 of those returned by end users as “not working” has nothing wrong with them. From: Kent Osterberg Sent: Monday, January 24, 2011 10:39 AM To: RE-wrenches Subject: Re: [RE-wrenches] 10A Charge / load controller The spec sheet for the SS-MPPT says 75 volts maximum open circuit. Maximum PV power: 200 watts for 12-volt batteries and 400-watts for 24-volt batteries. While it is supposed to be protected from PV overload and PV high voltage, it doesn't seem surprising that failures that have been observed are in systems that are pushing on these limits. Fortunately, Morningstar stands behind their product. Kent Osterberg Blue Mountain Solar, Inc.
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