There are only two pieces of solar equipment which should be specifically designed for a grid-tied system:
- Grid-Tie Inverter (GTI) or Micro-Inverters
- Power Meter
Grid-Tie Inverter (GTI) synchronizes the phase and frequency of the current to fit the utility grid (nominally 60Hz). It also adjusts the output voltage so that it is slightly higher than the grid voltage, which makes excess electricity flow outwards to the grid.
Some homeowners prefer micro-inverters, which are much smaller and go on the back of each solar panel. While micro-inverters are more expensive than string ones, they are proven to yield higher efficiency rates. Those who are suspect to shading issues should definitely opt for micro-inverters.
Finally, you'll need to purchase a power meter (often called a net meter or a two-way meter) that is compatible with net metering. This device is designed to measure power going in both directions, from the grid to your house and vice versa. Note that some utility companies may issue a power meter for free, so consult your utility before buying.