Fronius IG inverters offer high efficiency, precision maximum power point tracking, and intelligent thermal management, all of which result in superior energy output from grid-tie photovoltaic systems. Their wide input voltage range (150-450 volts) permit the use of modules in any power and voltage range. Their light weight and innovative mounting hardware make them very easy to install. Fronius IG inverters come standard with an integrated LCD that displays and records over 20 parameters pertaining to inverter and system operation. Fronius inverters have 3 expansion slots that allow you to add features like external sensors and remote displays. You can use a personal computer to update the inverter with the latest software upgrades. The larger inverters (over 3 kW) are built with the same power stages as the smaller ones, but use 2 of them. When these inverters see array capacity at less than half, one stage turns off, giving the inverter higher efficiency during periods of low insolation. UL Listed. 10-year warranty. Extended warranty available.