i have 2 sonic rodent repellent devices in my 24' X 22" garage, i haven't had a mouse in several years..... that is why i installed them, mice over running my garage. i keep a baited mouse trap in the garage as well, just in case 1 slips by but it hasn't gone off in years.
i saw solar powered ones, making them portable(mine plug into the wall). they are suppose to be good for voles, moles, gophers and other rodents but i would questioned anything solar other than LED lights. the solar units have mixed reviews.