In summer, the battery lasts quite long, thanks to the small solar module on the device. In winter, however, the batteries are empty again after just one day. However, the batteries supplied are also not of very high quality, and if you replace them with better ones, the time until the next charge is 2-3 weeks.
Windhager's pet repellent can be installed in areas that receive occasional sunlight, but it doesn't have to be in direct sunlight all the time. The housing is weatherproof, which means it can withstand a variety of weather conditions, including sun and rain.
I never had the impression that the solar cells noticeably charged the battery. This is rather negligible. The batteries supplied are also of poor quality. My own batteries lasted longer.
Windhager's pet repellent is designed to repel animals outside without affecting animals inside. It generally uses ultrasound or specific odours that don't penetrate buildings, meaning your cat inside shouldn't be affected.
According to the information found :
APPLICATION
Easy to use. The solar-powered defence device can be fixed in the ground with the supplied ground spike or suspended from the notch on the back of the device. The integrated infrared motion detector activates the ultrasound, the intensity of which can be adjusted by two rotary switches (ultrasound intensity and programme) in a frequency range of 17 to 23 kHz as required. The programmes [0-5] cover different operating modes from 0 inactive to 5 strong frequency intervals.
We recommend that you observe the behaviour of your own pets on the ultrasonic repeller and reduce the intensity if necessary. The best results are obtained when the sound is free-flowing.
Here is the response I got from the department responsible.