Many people consider bats to be pests and automatically assume that there must be a spray to solve their bat problem. Bat repellents in a chemical form would be classified as a pesticide in Michigan and are regulated. The products that we have observed are made out of the same chemicals as moth balls. We have observed many bat colonies in homes where the attic contained moth balls. This will just make your home stinky.
Other bat repellants are ultrasonic noise makers. We have not found these type of repellants to be effective.