If you don't bond ground to earth in the main box, your Hybrid inverter will be live in case of a circuit or electrical current fault. NO!, a ground stake will not fix the problem, they do not draw away lesser deadly currents only electricity from lightning, they have high impedance where the neutral at the bus bar in main box, has low impedance and fault current will be quickly expedited to neutral tripping the circuit breaker, not passing thru a human, in case of electrocution. Bus bar bonding in main box is to STOP electrocution, ground stake is for lightning strike, to minimise episodic lightning damage, not stop random electrocution.