Permanent units are fully automatic generators that can be installed next to a home or business in a fixed location. These units typically can perform such functions as monthly self-tests and systems checks. They generally are directly wired into the main breaker panel and can operate the entire facility or a part of it in the event of an outage. In addition, they automatically turn themselves on when they sense a power failure. While these units are the most expensive to purchase, they are also the most convenient to operate.