http://www.247wildlife.com/batultrasonicsound.htm

Ultrasound has been shown to have a deterrent effect by research looking at keeping bats away from wind turbines. But it has limitations.

Evaluating the Effectiveness of an Ultrasonic Acoustic Deterrent for Reducing Bat Fatalities at Wind Turbines

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0065794

Testing the effectiveness of an experimental acoustic bat deterrent at the Maple Ridge wind farm

https://tethys.pnnl.gov/sites/default/files/publications/Horn_et_al_2008.pdf

Field test results of a potential acoustic deterrent to reduce bat mortality from wind turbines

https://wild.nrel.gov/sites/default/files/Szewczak_Arnett.pdf

Bat Deterrents: How to keep bats away from wind turbines

http://www.nature.com/scientificamerican/journal/v311/n3/full/scientificamerican0914-29.html

There are a number of domestic ultrasonic bat repellers on the market however I've not come across any published research on their efficacy and as with so many other sonic repellent devices the feedback is variable; see some contrasting opinions below:

http://www.ebatremoval.com/60-day-trial-offer/do-bat-removal-devices-work/

http://www.247wildlife.com/batultrasonicsound.htm

Looks like an opportunity for someone to do some controlled experiments!