I had bats actually come in my Attic a few years ago and asked Woo this same question. He told me to hang a tarp over the opening the idea being bats have a certain approach they like, kinda like an airplane does the same way each time, down wind, base leg, final approach. By hanging a long tarp over the opening they can't access the opening the way they'd like to and basically move on to somewhere they like better.
I also field plumbing questions
I also field plumbing questions