Bats in Porch Ceiling
Put a bright light in the ceiling that will shine all the time. That might move the bats away. They will likely leave in the evening when they go out to search for food. That is a good time to check to make sure they are out, and then block entrances. I am including the URL for a fact sheet on bats that may offer other suggestions: http://icwdm.org/handbook/mammals/mam_d5.pdf
After looking at the fact sheet, if you have additional questions, get back in touch.