Inverter question - DC inputs vs Strings?

[themightykc]

Dear all,

I am a little confused regarding DC inputs on inverters and strings that an inverter can take. For example, I have a Fronius IG 3.6 here which has 6 DC inputs, but does that mean I would be able to run 6 different strings to combat shading problems? From my understanding, 6 strings would allow me to have 6 arrays on 6 different roof aspects, is that correct? Or does somebody have a good website describing strings and the DC input differences?

Help would be much appreciated.

A

[Mike90250]

The keyword to look for , is Independent MPPT , otherwise, they are just parallel terminals. (you can verify with ohm meter before you connect any power, or connect 1 array, and try to measure voltage on the other 5. I think you will discover they are "combiners" and not independent.)

I know of no controller with 6 MPPT channels. I've heard there is one with 2 MPPT channels.

[themightykc]

Thanks Mike,

Just had a look at an SMA SB 2500 HF and the inverter itself has 1 MPPT tracker but 2 strings. Is that possible? And if so, could I have the solar modules on two different roof aspects and how would this affect shading? (sorry for all the questions!)

Cheers,

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[Mike90250]

Each MPPT tracker, can only manage cells/panels that are the same, and aimed in the same direction. If you mix arrays, it will "hunt" between them, with less than good results. Just having 2 or more sets of screw terminals, does not make MPPT magic happen.

[themightykc]

Cheers Mike,

Thanks for the help, much appreciated.

A