Thanks for the suggestions. Let me give you more detail.
I have a solar array fed into an inverter (120 VAC output) that in turn goes to standard loads AND charges a 10 kWh battery bank. The main inverter is of the grid-tied type, which means that if it does not sense 120 VAC 60 Hz from the grid, it shuts down. I want to use the PV array and inverter OFF GRID, so there is no grid voltage to keep the inverter on. Since I cannot afford to replace the inverter ($2000+) with a non-grid tied model, I am trying to fool the inverter by connecting a very small (inexpensive) inverter (powered by a small 12 VDC gel cell) to the main inverter so it thinks it is connected to the grid. But I need to keep the current from the small inverter low so that when the sun goes down the main inverter does not draw down the little 12 volt battery, which would quickly shut down the system. I also need to keep the current flow between the two inverters very low so that the small inverter is not damaged by back flow from the main inverter.
So I'm trying to limit current flow both ways between the two inverters to maybe 10mA, but keep the voltage at 120 VAC and 60 Hz.
Many thanks to all the great minds tackling this problem!