A lot of alternative power systems are advertised in the magazine Solar Today. This is a good resource.

One of these systems is made by Xantrex, which is a division of Durcell. This system mates utility power with a conventional standby generator, a line interactive inverter, a battery bank, and solar cells that can be augmented with wind power. For North American power systems, it comes in 120/240 single phase, 120Y208 3-phase, and 277Y480 3-phase. For 277Y480 3-phase lower voltage inverters are cionnected through a stepup transformer.

There is somebody over at www.eng-tips.com who has one of these and says that it is very handy given that they have frequent power failures. Getting most of the standby power hours from the solar cells and the inverter and only needing to run the generator for heavy loads saves a lot of wear and fuel consumption for the generator. The inverter is both line interactive and generator interactive. The inverter can also charge the battery from either the utility or the generator on cloudy days.

This system is essentially a hybrid car without wheels.

The way that single phase 3-wire and 3-phase 4-wire interactive inverters work is that there is a set of 2 or 3 2-wire single phase inverters with an interconnecting cable(s) that maintain the inverters at 180 degree or 120 degree phase differences.

There is another manufacturer of these systems but I forget who they are and my other computer is not inuse until I have enough energy to upgrade the disk drive and reload Windows 2000.