Do I negotiate net metering with the utilities company, or will the solar company do this?
The solar company will do it, or you can hire an electrical contractor to do it for you.
The solar company you went with should take care of this for you.
Utilities won’t “negotiate” with you any more than you can negotiate an item’s price with a checker at a grocery store. Typically, there is a form the utility will want filled out. Your solar installer will do this for you and provide you a copy if you ask for it, and your signature will be on it. Different utilities have different requirements. Sometimes, they want to approve the design plan before the installation goes forward to make sure the meter meets certain requirements (height, right size feeder wires, etc). After everything is installed, they come and put the “production” meter in the meter socket the installer put in and swap your existing “net” meter for a bi-directional meter. The net metered rate you get paid is typically something set by a local authority.
Your solar installer should be doing this for you. At most, you will have to sign the final agreement.
Net metering is an agreement between you and the utility. You won’t need to set it up yourself, your contractor should handle all of the interconnection paperwork. If not, get a different installer.