In Michigan the Little Brown Bat and the Big Brown Bat are the most likely to use Wild Birds Unlimited bat houses which meet the specifications determined by Bat Conservation International and the Organization for Bat Conservation. Bats find the bat houses just like birds find bird houses. If a house is in the proper location, meets the bats’ requirements and is needed, bats will move in on their own.
Bats like it high and hot so you should place the house at least 15' above ground for the best chance of occupancy. Houses should have an open area below because bats like to "fall" out of their box at night and "swoop" back to the box in the morning.Bats like to get at least four hours of direct sunlight in the morning. If you don't have a place with enough direct light you can paint/stain your bat house a darker color to help it absorb more heat. Please note that these suggestions are for Michigan bat nesting boxes.
Bat houses are often placed on the side of a house, garage, or barn. Dead trees can also work, but live trees are usually too shaded. If the bats don't seem to like the placement of your box within a couple full summers, it's time to try a different spot. Sometimes we feel that we have the perfect place, but the critters just don't respond. Experimenting is the hallmark of wildlife attracting. Just remember, think like a bat.