Monocrystalline cells are more efficient, but only about 8%. Polycrystalline cells are normally used in off grid systems, as they are a cheaper panel and are only used to charge the batteries.
Power generated by the silicone cells is transferred through a DC isolator, through an inverter which rectifies it from DC to AC, via a renewable energy meter known as a smart meter. From here it is connected to a fuse way, in your fuse board, and goes back out to the main electricity supplier.