One or two MPPTs?

[rost]

Hi,

I have a 15kW inverter with two MPPTs, one (MPPT1) with two string input paths and the other one (MPPT2) with one string input path.

To this, I have two strings of 415W shingled solar panels (Voc 46.7V, Vmp 38.9V), one string with 15 panels facing NE and the other one with 18 panels facing SW.

The inverter's "sweet spot" is 450V-850V per MPPT (not per string input).

Would you connect both strings to MPPT1 or one string to MPPT1 and one string to MPPT2?
Please elaborate why, so that I can learn something new.

Thanks!

 

[meetyg]

Each string is well over the minimum 450v at Vmp. Since they are facing different directions, sounds like each on its own MPPT is ideal.

 

[rost]

Are there any benefits using only one MPPT with two strings? Maybe one string is helping the other being more efficient in shadowy/bad conditions? Or is it just confusing the MPPT algorithm having two different voltages connected to it?

 

[meetyg]

Are there any benefits using only one MPPT with two strings? Maybe one string is helping the other being more efficient in shadowy/bad conditions? Or is it just confusing the MPPT algorithm having two different voltages connected to it?

Just confusing the MPPT. Having that these strings are unequal in voltage AND that they are facing different directions, on string might pull down the efficiency of the other.