I have an AC-coupled off-grid system with 2 solar arrays. One array (4.3kW) is connected to a Fronius inverter and the other (6.3kW) to a Multiplus. On a cloudy day, I believe that I should get approx 10% solar gain on each. However, on the Victron system my gain is approx 450w (i.e. about 7%) and on the Fronius my gain is approx 2%. Both arrays face north and are on similar pitch i.e. about 30 deg. Both arrays are cleaned regularly. Any views on why such a descrepancy?