The (NEC) National Electric Code for 2020 now requires two grounds rods for residential units spaced greater than 6-feet apart. Most homes do not have this since the code was only recently adapted. You might try installing a second ground rod. Homes located where the soil is very dry, may not be getting a good ground. (I recently installed a second ground rod at my home. We live where the soil is always wet/moist.) The cost is minimal for the materials. Lowes or Home Depot will have the supplies you need. Just be careful where you pound the second ground rod. You don’t want to destroy underground electrical or plumbing.
Here is an article I submitted several years ago. Try cleaning your current outside grounding connection. Corrosion may be creating an issue.
If neither of those ideas help, then you will need an electrician to inspect your breaker panel ground connections or the power company will need to check their grounding at their transformer.
Or the issue may be at the Solar/battery installation. Can you submit some pictures of your panel, setup, wiring connections, etc. to the forum?
Or possibly an animal has tunneled under your transformer and piled up dirt that is creating issues on your power leads like this transformer in our neighborhood. The exposed aluminum metal connecting bars on the right side should not be contacting any ground/dirt.
Good Luck.