HarryN
Solar Wizard
He should use a transfer switch so that you can switch to generator input or grid input. However, keep in mind that this is a grid tie inverter, and they're very picky when it comes to the quality of the sine wave. In addition, you must prevent the solar side from trying to back-feed to your generator as if it were the grid.
That might be the easiest method. Either turn off the solar first or run the generator when the sun is not shining.