Re:Use a 'fan center' to isolate when grid power d (Score 1)

PWM is about modulation of a square wave (achieved by comparing a triangular wave with a pure sine wave using a comparator). If modulated just right i.e. if the modulation index is optimal, using the leakage reactance of the output transformer, the HF square wave is easily filtered off leaving a pure sine output!(99% pure sine with a conversion efficiency of about 95% at optimal load) Simple concept isn't it? Actually not :) To add to this complexity is the fact that the input to the modulator needs to be in synch with the mains! This should explain the cost of $2K upward. I see the mention of brushless motor here. Spoils the game you see.... moving electricals are notorious for their pathetically low efficiency. How low? Well a bad bad 30%!! So compared to a PWM system you may end up using 4 times the number of solar cells to get the same power.