Thank you for the info.
During the day when the solar is operating, any power that we do not consume automatically feeds into the grid and our meter runs backwards. If the grid goes down, for whatever reason, a switch is automatically thrown and the system switches from being connected to the grid to our backup propane generator that feeds the solar system enough power to keep it up and running. If our system does not "sense" any power coming in, it shuts down, thus the generator when the grid goes down.
Any grid-tied system is required to shut off when the grid goes down so that power company workers don't get electrocuted while repairing the grid system. Since that would have left us without power during an outage, we decided that the generator backup was necessary. We are close enough to the coast and tropical weather that we are prone to long outages in hurricane season. That kind of defeats the purpose of having solar power, so we figured out how to get around that.