Bat houses are great, but bats are particular and you never know if they will occupy one or not. Why is not fully understood. You can have two identical bat houses in a yard and one gets occupied, the other does not.
I did a bit of research about bat houses before purchasing one for our yard at our mountain home near Lake Isabella, California.I got mine from Bat Management — http://www.batmanagement.com/Ordering/ordermain2.html. They are a small company in Pennsylvania that specializes in bat gear. I would recommend getting a bat house from a supplier that actually works with bat houses. Amazon doesn’t care about selling bat houses, only about selling something. Many of the bat houses on the site are too small. Bats don’t like small bat houses, partly because the internal temp will vary too much.
Because bats fly, they move around a lot looking for food. Some bats will travel many miles for good feeding grounds, though the common myotis bats probably not travel more than 0.5-1.0 miles. They are the ones most likely to use a bat house. That can be a big deal to having bats around to help control insects. And it helps bat populations suffering from white nose syndrome.
If you have troublesome bats roosting in your attic, have a bat “exterminator” who knows what he or she is doing come out to your place. If they know what they are doing, they will not recommend killing the bats (it is illegal anyway in most areas and that would stink up your house). They should evaluate your house to see where the bats come and go from, then put a special “exit-only” tube there. That way when the bats leave at night, they cannot get back in, and the exterminator can then close up all the holes where they get in (it doesn’t take much of a hole in size for bats to come in).
If you exclude bats and have bat houses up, there is a better chance of them starting to use the houses.