How about paralleling two strings with different number of panels? Im planning a setup with 23 panels, 15 mounted on roof and 8 on balcony, all facing same direction, although the angle of roof is 2 degrees less when compared to balcony mounting brackets. Considering my options on 2+1 MPPT inverter I have either 7+8 and 8 (separate connections for roof and balcony) or 8+8 and 7 (mixed connections)