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I have just bought a house that has two grid-tie solar inverters. Photo1 Photo2
I've read the owner's manual on the inverters and they only do full power generation when there is incomming utility power. They will each run a single 110v outlet at 10amps without utility power, but I want more.
I also have a 6,500 watt Champion portable generator.

My question is, could I have a transfer switch installed that would allow my generator to provide the utility power that would enable the inverters? How would a portable generator handle backfed power? Is this just a horrible idea?

I'm not a math whiz but I would think burning gas in your genny wouldn't be productive in trying to get free power from the panels. Plus I'm almost 100% positive generators are not supposed to be connected to any type of backfed power... 

ETA: think you need to look into a hybrid off grid/grid tie system to make it work, but don't quote me on any of this. I'm just a guy 

Horrible idea...  

Most generators don't have a clean enough output for a grid-tied inverter to recognize it as "the grid".  And even if the inverter does start up, the generator will see that as a load drop and adjust output accordingly.  That usually meaning it goes out of frequency.  Inverter will go back offline.  Vicious circle of SNAFU ensues.  You could even roast the generator if the PV system is big enough.

And if these are SMA inverters, they're very good about shutting down when the grid is wonky.

It's a lot of work and money to make a grid-tied inverter work when the grid is down.  Rarely worth it unless you have a lot of outages and want to spend the time/money to install a protected loads service panel.  

I do solar for a living.  Less than 1% of it is for off-grid or battery backed applications.

That's what I was afraid of. At least the solar will run my fridge when the power is out. Thanks all.

What about installing a offgrid style inverter that you can use independently of your grid tie units.

Old style inverters still require battery banks.  We call it DC coupling.  Solar modules to Charge Controller to Battery to Inverter - all DC until the output of the inverter

Additionally, grid-tied solar modules are wired up for much higher voltage than is typical with an off-grid system.  So getting a charge controller that works ain't cheap or even feasible sometimes.  You can rewire the array, but that's a PITA that means lifting modules.  

We started using AC coupling about 5 years ago.  We get a battery powered inverter that passes the grid to the grid-tied inverter when the grid is up.  When the grid goes down, the battery powered inverter "pretends" to be the grid.  The issue with this scenario is that once again you need a protected load panel that's isolated from the grid via the battery powered inverter.   Looks kind of like this:



In a year, I design maybe a 100kW worth of these AC coupled systems and maybe 50kW worth of DC coupled systems.  As opposed to the 5-10 MW of strictly grid-tied systems I deal with in the same amount of time.  

Batteries are a serious weak link - because of either longevity or cost.  Nothing on the market solves that weakness.