This is the 20 kilowatt 2 cylinder Detroit Diesel that provides supplemental power when I really need it.
These units came out of the Santa Fe Railroad system probably back in the 1950's. They were used to power refrigeration cars while transporting food across the country. There are a few of these units available on Ebay from time to time. They are 120 volt three phase alternators. This unit rarely comes into operation except for weekly exercising, but it can supply enough power for the most demanding house if required.
In order to start the diesel in hot or cold conditions, I mounted an ether injection system to give a shot of either just before cranking.
Since these units were not designed for remote starting and stopping, I had to improvise to make the stopping remotely. I did this by placing a 12 volt high torque solenoid on an aluminum plate to make the plunger pull the racks to the off position on demand.
The Zantrex (Trace) SW4048 is a 4000 watt power inverter system that acts like a whole house U.P.S. system. If the mains fails it takes the 48 volts from the battery bank and converts it to 120 volt sine wave. It is instantaneous so I don't even know when it happens. The batteries are kept charged by the 3800 watt solar array. The diesel generator is also connected and controlled by the SW4048. It has the necessary logic output to send commands to the generator to shoot the ether, crank the generator, wait for the generator to come up to full output, and then transfer from batteries to the generator. (It will make several attempts to start and if it doesn't, it will sound an alarm.) All this happens so fast that there is no interruption in power to the house. Once the mains has been reestablished, it will transfer the load back to the mains. This unit will also exercise the generator once a week to make sure the system is always ready.
A nice feature of this system is that if the solar power array has excess power, it will sell it back to the grid and the watt-hour meter will run backwards. Most states in the U.S. now allow us to "sell" power back to the grid. We just cannot get paid for it. Since I use more than I sell, that is not a problem. I just have a smaller power bill.