Bats are constantly on the prowl for suitable alternate roosts.
If a bats can be seen occasionally at dusk, then likely the area should support a new bat house. If the box is to be used to help evict bats from a structure, then ideally the box should be placed on the structure itself. It is also ideal to have the box near the bat's entrance into the structure. However, seven hours of direct morning sunlight is of paramount importance and outweighs all other factors. After the second year of occupation, the box may be moved off the structure and onto a pole several hundred feet away.