Net Metering allows you to reduce your utility bills by gaining credit for energy produced. Under Net Metering you are reducing the amount of energy you purchase from your utility.
Feed-In Tariff is for solar electric (PV) or Wind technologies only. Select this option if revenue is created through the sale of all the electricity produced.
Gross Metering is offered by some utilities, instead of Net Metering. Gross Metering is similar to a Feed-in Tariff (FIT) structure in that it allows you to receive income (revenue) from the energy you produce. But unlike Net Metering, the amount of electricity you purchase from the utility does not change to a Net amount (energy use less energy produced). Rather you receive revenue for having produced electricity and feeding all of it to the electric grid. Sometimes this revenue is received in the form of a credit on your electric bill rather than a separate payment.