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Wrenches, Please tell me if I'm overlooking something, in what appears to be a design weakness: I would like to use an Outback Radian system for a standard GTBB system. In order to take full advantage of the system's capabilities, I have to use all of Outback's main components; in this case the FM60 or FM80 charge controller. The problem is that the most common (and lower-cost) modules today are 60-cell, meaning 20 Vnominal. Given the 150V DC hard maximum voltage limit of the FM-series charge controller, in our cold climate I can only use these 20V modules in 60 Vnominal series strings; that is, in multiples of three modules. As the Radian is (wisely) offered in 48V only, pairs of modules would provide too low a voltage, and series strings of four modules would exceed 150 Voc in cold weather. The base Midnite Classic 150 will safely operate to 198 VDC in this application, but it won't communicate with the Mate3. Is this a fundamental design limitation in the Radian system, suggesting that Outback is due for a controller upgrade, or am I missing something obvious? It appears that arrays and racks have to be sized in ~720-watt sets of three-module series strings, which can be problematic in some designs. In the design in question I would like to use 16 240W modules on two 8-module pole-top racks (for seasonal adjustability); nothing in sets of three meets the customer's output and aesthetic needs. Any solutions would be welcome. Thank you, Allan --
Allan Sindelar [email protected] NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder and Chief Technology Officer Positive Energy, Inc. 3209 Richards Lane (note new address) Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com
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