Here's a question for you, but first some info....
I have some solar PV with a grid tie inverter. When I'm generating say 800W and using say 1000W I will buy 200W in from the grid. If I use 500W I "sell" 300W back to the grid.
All of this happens automatically.

Right so I now have a wind turbine which I have connected to some batteries. Off the back of this I have an inverter (not grid tie). I can plug in power tools and everything is fine.

Now lets assume the grid fails. My PV system has to disconnect, so I am without power but wait! I have my other supply so I could run an extension lead into the house and use that

So at long last to the actual question.
If I disconnect from the grid (main breaker off) and connect the battery / inverter into my house supply the PV grid tie would (I Assume) sync up to the new mains supply.

So back to the usage
If I generate 800 and use 1000 would I pull 200 from the battery inverter? and the rest from the grid tie?

However if I only use 500 I would have 300 "spare" so what would happen?
Would the inverter just switch off? But then the PV grid tie would switch off
Would the inverter explode as I was feeding it with 300W?
Would the 300 just vanish (where?)

No one knows.

The performance depends on the controller/invertors. As they were not designed for your intended use, no one knows what will happen. You could try it out, but you may damage one or more invertor/controllers.

I can tell you one thing: the 300W won't just vanish. It'll probably do something nasty somewhere.

_________________
I should be dead; I've cheated the Grim Reaper yet again by surviving my third heart attack in June.

Thanks,
I'm not intending to be the one to test this, just wondering really.

If the grid fails then I would be best off running an extension lead rather than messing about with switching things off and risking a big fat electrical horror.

Mind you I could put the picture of the burnt out unit on the rouge pages on UHM. Even better if it burn down the whole house.

Phill

I think you will ask for trouble if you parallel up 2 the inverters they especially the wind turbine one could be modified sign wave type and the output transistors/tyristors would be damaged in my opinion.

I have 2x inverters, a lumpy modified sinewave which I use for power tools (these are very cheap) , and a nice pure sinewave (much lower output, as they cost a fortune) which I use for battery chargers etc.
So the assumption would be to use the pure sinewave for this "project".