How hard would it be to install some sort of switch into my grid tied system so that if there were a long term power outage I could still use my solar panels (during the day of course) to power my home. I'm no electrician and I know that there is a good safety reason not to do this, but like I said, I'm just curious.

Thanks.

a switch won't fix that problem as your pv system is most likely setup for hundreds of volts. most backup power setups use battery banks between 12v and 48v and the pv voltages regulated with a charge controller that usually can't take the higher voltages presented to it from your grid-tied pv system.
can you be more specific on what your setup entails?

I'm dieing for the same thing, and finally got a couple of 500W 300V - 28V DC-DC converters off epay, and figure I'll rob the cars of starter batteries to keep the fridge cool.

It's not a cheap or easy thing to manage.

that presents an interesting scenario mike as that 28v is not high enough to properly charge a 24v battery bank and would need further regulation to go to a 12v battery bank. that is workable during an outage, but what do you do to keep the batteries charged when no outage is occuring, which i hope is most of the time? this could benefit from a grid charger and have the pvs and converter as insurance against long term outages making solar quite secondary for the batteries as the pvs are primary for the grid tie inverter.
after all of those losses you may as well have just made a tap into the pv string to extract a high voltage, but with a lower voc than the max operating point of the controller picked to use. this of course should only be done when the grid is down (ie emergency) as the shared pvs cannot deliver their full power to both the grid and the batteries at the same time and is why i sited the need to have the grid charge the batteries with a charger during non-outage times.
the above tap idea does present a scenario i would like to know if solar guppy would know the answer to it or elaborate on the possibilties of. say the emergency happened and you tapped the pv string to supply power of a lower voltage acceptable to a controller and through said controller and then to the battery bank you had maintained with a grid charger. all of a sudden the grid gets restored and the pvs are still tapped for the battery bank and the grid-tie inverter is now ready to start supplying power to the grid again. seeing as how those tapped pvs cannot supply both loads fully what would happen? would the string be just lowered in its current capacity and deliver a smaller amount of power to the grid due to the batteries sucking power from the tapped pvs or would something blow? this may even have a backfeed through a connected grid charger. would isolating the battery system be warranted with a disconnecting of the grid battery charger and the inverter to prevent an unknown reaction or interaction or would there be just a division of power delivered to both systems with no catastrophies? or would the solar pv battery charge tap rob the inverter system altogether and stop it from operating?
a sidenote is that when a small amount of power is taken from a few pvs of a series string, this is equal to dissimilar pvs being in series by the amount of power being robbed from the tapped pvs. mike, you are proposing a tap across all of the pvs and also presents a scenario unto itself as a sharing of power may occur, or will one or the other winout sg?

Not to mention that if you wanted to charge batteries with a grid tied inverter, it wouldnt work because the second the grid goes out, so does the inverter, regardless of weather its connected to the grid or now. No Sine Wave = No inverter power up.

Here is a different Method to consider. You could purchase a Sunny Island and connect your grid tied inverter to its AC Backup side. In this scenario the Sunny Island creates a sine wave for the Grid Tied inverter to lock on to and then once the Grid Tied inverter starts, the Sunny Island will use the energy thats left after household loads to charge the battery bank. The sunny island will also use the battery power to supplement the power from the Grid Tied inverter durring times of heavy load. This essentially creates an AC-Coupled or AC-Centric system which is its own mini grid and uses the Grid Tied inverter sortof like a super expensive charge controller, except the control/regulation is on the sunny island. This system would be capable of battery charging, backup power, and selling to the grid just like any good battery based system. This would also maintain a higher operating efficiency than most battery based systems and the energy would be used by your hom first, then batteries, then out to the grid. The downside of this system is that it would add a cost of about $7000 to start and about $10,000 to really do it right with a decent sized battery bank.
Just FYI, it is also possible with a Xantrex XW system, but it is more complicated, only works with Xantrex GT inverters and it may void the warranty of the XW system. This is the road I'm going down. It's a less expensive inverter and I already have a funtioning battery system and GT Inverter. My current battery powered inverter is running off a 750 watt array compared to 3010watts on the GT and the inverter is only a trace DR-3624. It works for now.

The DC-DC converters have +- adjustment, so proper voltage is not a factor.

Batteries are living under the hood of the cars right now. This is emergency conditions, not a UPS style system. A car battery will run a couple CFL's all night, no problem. Sun comes up, it recharges from downconverted PV output.

Grid is gone

I hope it never needs to be "McGivered" together, but I have parts
to do so. ( I hope ) None of it would pass code.