I have no expertise in this, but I have the same thoughts as 90cummins, and have been thinking about this for a few years. All I have right now is a Honda EU6500i through a manual transfer switch. I love the inverter feature on this for managing demand load and fuel efficiency, but I would prefer diesel, and I would prefer to have it coupled to a battery bank rather than being dependent directly on load. If the battery bank is viewed as a large capacitor, power really only needs to run to recharge the capacitor rather than to meet demand, unless you have run the capacitor down and still need to meet large load demands. Inverter technology today is fantastic. Why not marry the best of inverter technology with efficient power curves on a diesel used to charge batteries rather than power the load directly? I don't know why this isn't more readily pursued. The boating industry seems to already understand and use this approach. Those little Yanmars are good engines and could be run on biodiesel if truly needed in the future. Maybe I'm missing some big problems?
90cummins, have you considered battery choices? I have been considering the Ediison nickle/iron approach. It's much more costly at first, but when you factor in that they can support much deeper discharge cycles without doing damage to the cells, the cost difference narrows considerably as to capacity. They have a much lower energy density per weight, but who cares for stationary home uses. They don't off-gas hydrogen, and so they are much safer. You can regenerate the cells yourself and are virtually indestructable, and don't require the use of dangerous acids. They can support rapid DC charge cycles, including modern pulse technology methods. So, when coupled with a diesel DC generator and a high quality inverter, it seems to be a good match to me. But they are hard to find in the US, and most solar installers don't know anything about them.
