Automatic AC transfer switch

[Xringer]

Generator Transfer Switch

These things are designed to kick in the aux power when the grid fails..

But, I want to twist that idea around and built a switch that kicks-in when there
is aux power available.

It would work like this..
1.When the sun came up and hit the PV and got the batteries charged up a bit,
2. a battery voltage monitor circuit would turn on,
3. and apply DC (Batt+PV) power to a 12VDC to 120VAC inverter. (The inverter is my Dump-Load).
4. The AC output of the inverter would disconnect my computer (wifi router etc) from the grid.
5. 10 msec later, it would connect the PC to the inverter..

6. When the clouds come in, the batteries keep me going for a while..
But when they start getting low, the battery voltage monitor circuit will switch off DC to the inverter.

7. The relay pops back into NC and the PC is back on the grid.

I wonder if someone makes these things?
I've seen some PV charge controllers that have a 'load' output.
Some of them don't provide a lot of amps on those terminals,
but they could be used to switch the inverter in and out..

Comments please:

Cheers,
Rich