How to wire off grid inverter to main breaker panel??

To make a long story short, it's not practical to build a grid-tied system if you have only two PV panels.  You'll need permits, a grid-tie inverter, and the services of an electrician to hook things up.  This is a large expense for the small amount of power you would get from your system.  If you really want to build a small-scale PV system consider off-grid.  To answer your question;  you would use a transfer switch (automatic or manual) to connect your inverter to your house wiring. You should get an electrician to do the wiring, unless you have electrical wiring experience and are familiar with the electrical codes. 

Since you only have two panels, you might consider doing what I've done.  I didn't wire into my electrical panel.  I use an automatic transfer switch to control power to only two items, my refrigerator and freezer.  I've set it up to use batteries (through an inverter of course) as the primary source of power, and automatically switch to grid-supplied power when the batteries get weak.