Inverter Efficiency
The inverter is an electronic device which converts the direct current (DC) electricity that comes from the solar panels into alternating current (AC) electricity which matches the AC frequency of the power lines. The inverter also matches the AC voltage of the power lines, but sets its voltage slightly higher so that the energy from the solar cells is pumped back into the power grid. This runs the electric power meter backwards which gives the customer credit for the kilowatt-hours of energy produced by the solar panels. Like any such device, there are some losses of energy in the form of heat. Therefore an efficiency rating for the inverter is required to calculate how much power is actually produced and fed back into the electric grid. A typical inverter has an efficiency of about 94%, so 6% of the energy produced by the solar cells is lost in this conversion process.

The inverter must also be able to disconnect from the power grid at certain times. For example, if there is a power failure on the grid, it would be hopeless for your system to power everything else. So to protect your system, it must quickly disconnect. Also, if there are power company service people working on the power lines, they must be able to disconnect such a power source from the wiring so that it is safe to work on the power lines. The inverter has provisions for such remote control and also sends information back to the power company reporting how much energy has been generated.

Note that if you will produce more power than the input capacity of the inverter, you will need to buy more than one inverter or use a larger capacity model. In some instances, a fan can be attached to the inverter which will allow it to handle a slightly greater amount of power. Here are some inverter models approved for grid use.
Efficiency Inverter
97.6% PV Powered StarInverter PVP2800
94% Sunny Boy 2500U
91% Xantrex STXR2500