I have a client for whom we just replaced 30 batteries feeding a UPS system. The UPS takes power from the utility or an inverter for the batteries. The feed into the inverter from the UPS bateries is two legs of DC @ 12 x 15, or roughly 180 VDC per leg, output is 230 VAC into the UPS.
He also has an 8kw manual start, stand-by generator that he may plug into the panel. He uses a manually operated transfer switch, disconnecting the utility feed and engaging the genset.
Recently, he had someone else install a solar system feeding into the same panel. Therefore, the inverter will almost always be in parallel with another source of power, but only the utility can accommodate a constant full power back-feed from the inverter.
I do not think a standard grid-tie inverter is the right way to go. What inverter will automatically scale back its output so as not to overdrive the genset or the back up batteries on the UPS(like the demand is only 3 kw, it is the middle of a sunny afternoon, and both the solar and genset and UPS are online)?
