The solar panels in a grid-tie systems are connected to a Central or String Inverter to convert the voltage from the solar panels to a voltage compatible with the electric grid. A grid-tie string inverter must include the following characteristics for safe operation and comply with UL guidelines. The inverter must have a main switch to completely shutdown the entire system, it must have a Ground Fault Detection and Interruption (GFDI) device and an Arc Fault Detection and Interruption (AFDI) device. The inverter must be shut off for 5 minutes after the voltage in the utility grid drops. String inverters can be ordered in 240V, 208V and 277V configurations; some units are field configurable adjusting to single phase and three-phase systems. All central inverters feature a display that will show various production values such as daily generation, cumulative generation, current voltage, etc. Some inverters feature a series of LED lights in the front face that will alert the user when something is not working and needs attention from a technician. The inverter is the device that decides the main functions of the system such as when to start operations in the morning. It is very important to select the right inverter in order to ensure the best performance of the system during its 30-year life cycle. All inverters are designed for outdoor use; however, they should always be installed in a cool and well ventilated location and never in direct sunlight.