Grounding PV Array using Tranformerless inverter (SunnyBoy 3.8)

Transformerless Inverter

Grid-Tied with battery backup ---- Current system is a PV Array connected to SunnyBoy 3000 TL.  The grounding wire from the PV Array is connected to the DC Disconnect that hangs down from the SunnyBoy 3000 TL.

I am replacing the SB 3000-TL with the new SB 3.8  inverter.  The installation manual states to connect the equipment grounding conductor of the PV array to an equipment grounding terminal inside the inverter.  Does anyone see why I couldn't earth ground the array with a grounding rod instead of grounding to the inverter itself?