Likely not. Are your solar DC wires in conduit back to the inverter? What size are they? There is a chart in the code, it related the wire size of the +/- wires and the max current to the required ground wire size. For example, my array wiring back to the inverter is 8ga, and the required ground size is 10ga.
The 6ga (usually bare) is only required by code for “unprotected” ground wires that are exposed, such as those from panel to panel and bonded to the mount. Once you leave the unprotected open air and go into a junction box and then into conduit, you can transition to the smaller jacketed wire.
