I have using this invertor in my home since last 5 years. Very less maintenance is required and required which will be only of battery depends on battery which we connect to it. I am a electrical engineer so I known to all the technology used in the invertor manufacturing. Harmonic content is very less or we can say negligible in the output power of this invertor. If a system has low harmonics then losses in our home appliances are very less as compared to other invertors. If anyone ask me suggestion about buying invertor then I will suggest this only.