I'm trying to figure out how multiple AC sources which are in phase would be able to be used sequentially to power a load. This all started as I read some literature about solar PV panel systems which had a wiring diagram to tie output from the inverters directly into the electrical panel split phase poles. This being from a reputable PV inverter company. This system out puts 120 Vac split phase plus ground and neutral, it's a 4-wire output. I've attached a diagram to this post. I've simply represented the load as inductive for fun, no real point here. So here's the problem, wouldn't the MOST power that could be sourced from the non-grid AC be 50% of the load consumption? I'm not sure how these inverters work, but I'm assuming they will maintain 120 Vac up until they can't drive the current any more, and I would assume that they would then allow a voltage drop. I was thinking an op-amp circuit could be used for this difference to re-balance the voltage at 120 Vac. Otherwise, what I would think would happen is that the current from each source would be equal until the inverters couldn't drive any more current, at which point any additional current would be from the grid source.