Bats will tend to roost at night in sheltered areas like under a porch or in a shutter. Bats are not nesting they are resting. You probably wont see the bat or bats hanging during the day. The bats will seek areas like this to rest during their feeding time. You might see the bats hanging around two or three in the morning. To keep the bats from hanging try using some aluminum foil or shiny metal flashing and put it up in the areas where the bats are hanging. This will help keep them from hanging however it wont completely keep them from hanging around your house. Maybe you can at least keep them off of your front door step.