To have a successful grid connected project you have to work with the utility to make the interconnection go smoothly. Get the utility involved early in the process of planning. Many times your utility will have a dedicated contact for systems of this size range. 

They will also have technical interconnection standards for your equipment and special meters which may need to be installed at your service. You will also need to have a state electrical inspector sign off on your system before the utility will allow you to connect to the grid. The inspector will require that all electrical work, wiring and otherwise, be completed by a licensed and bonded electrician.