I have a Fronius Symo 8.2kW inverter with 10.08kW of 315W panels arranged as:
- MPPT1 - 12 in series
- MPPT2 - 2 parallel sets of 10 in series
When I look at the string voltage and current on Fronius SolarWeb (Analysis screen) I consistently see the 12-string voltage lower than the parallel 10-string voltage. It’s not uncommon for my parallel string panels to current clip at the 16A limit of the inverter but even at currents below clipping I regularly see about half the current on the 12-string MPPT with a lower voltage.
MPPT1 - 12.79A, 307.9V, 3832W
MPPT2 - 6.38A, 292.3V, 1818W
I know the whole current/voltage/power curve is non-linear for the panels but it seems to me that MPPT2 is not really operating at the same efficiency as MPPT1. All panels have equal sun exposure so if MPPT1 can produce 30.79V per panel (10 in series) then why do I only get 24.35V per panel on MPPT2?
Is there a setting for the MPPT which might be incorrect here or something else I can do to optimise this as it seems like MPPT2 could be doing more?
A screen shot shows the data.