@cali8484 as @jjrandorin has pointed out above, I can't really go in to detail. I'm actually surprised that swedges post is still present.
My PW's work just fine when the grid is out. I simulated this while I was pulling from the grid with the "go off grid" button and everything worked just fine. If the grid does go out while you're recieving solar then you'd have to go back in and change the settings to allow solar to be used again.
Thanks but I really don't get what's the warranty concern. You own the PW and it is perfectly capable of charging from the grid. What damage can happen from the PW charging from the grid? And if no damage then what is warranty support problem?