According to our information, both power supplies are possible, either battery or mains operation. I will add this to our specifications as soon as possible, thank you for letting us know!

The EufyCam has a rechargeable battery and also runs on continuous power. It also has a setting for an external solar panel to charge the battery. Works well, even in winter.
With little use (i.e. motion-activated), the battery charge lasts for a few months.