714 less 10% inverter** loss = 642.6 KWh
642.6 less 1% wiring losses = 636.2 KWh
636.174 less 8% transformer losses = 585.3 KWH
Without accurate on-site utility acceptance readouts the above figure gets within 7% of your estimated 540 KWh. Unless you sit and watch that readout until it turns over to next unit - or have access to utility accounting summary that is not shabby so far...
** http://tinyurl.com/6pd2yz <-- Spec PDF sheet, Max. efficiency 95.2% ~ 94.4%; doubtful it reaches that except at peak input (winter temperature PV boost) IF system is well balanced...
