Introducing Outback FlexMax Ultra Charge Controller

We visited with Brian, from Outback Power, at last month’s Solar Power International 2016, to talk about Outback’s new FlexMax Ultra medium voltage charge controller.

Brian: Outback’s very pleased to introduce our FlexMax Ultra series medium voltage charge controllers. It’s 250V plus battery voltage, so for most of our systems of 48V, we’re a 300V charge controller.

We’ve got three versions in the product family. We have 80A and 100A without arc fault protection, and a 100A unit with arc fault. The difference between the 80 and the 100 amp is we add a fan to the external heat sink in behind to provide some forced cooling over the heat sink to get us an extra 20A. 300V input limit. NEC compliant with the arc fault protection, very important with some of our market.

Other key features is it is NEMA-3R, it can be mounted outside. There’s no moving parts on the two 80A models. It’s a very high longevity because of the lack of the fan, that’s something very important to a lot of our customers. And the 100A unit can get over 6000W which exceeds any of our competitors’ medium voltage unit. So we are really excited to have this product offering. We’re going to start adding that next year into our FlexPower offerings, to make that feature available, too.

Available mid 2017!

About Author

Amy Beaudet
Amy Beaudet was in the solar industry at the altE Store from 2007 until her untimely passing in 2021. She was a sales rep, instructor, and an all-around solar evangelist, sharing her passion for solar around the world. When whe wasn't at work, she enjoyed sailing and skiing - but odds were good she was still talking about solar on the boat or on the slopes. See more of Amy Beaudet's blog posts.


  1. Melaney

    With a 4k off grid solar system, what size generator would you recommend?

    1. Amy Beaudet (Post author)

      That depends on what your loads are, what your inverter/charger can handle, and/or what your battery bank size is. There’s a few ways to look at it. You need to know the specs of your inverter/charger. For this example, I’ll use the Outback FXR3648A, If your inverter/charger can only charge up to 45ADC at 48V, it’s not much use getting a generator that outputs more than that. 45A x 48VDC = 2160W. However, if you have a high wattage load that needs a generator to assist the inverter, you may need to base the size of the generator on the load. Again, see what the max AC input for the inverter/charger is. If it is 60AAC x 120VAC = 7200W generator maximum, or whatever the spec says. If you have a smaller battery bank, and won’t use the maximum charging capability of the inverter/charger, and you don’t have any large loads to power, then you may go with a smaller inverter. For example, a 200Ah 48V battery bank getting charged at a C/10 rate would be 20A x 48V = 960W.

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