These types of modules are linked to your power grid. Your electricity needs will be fulfilled by the generated electricity first. If there is excess, it will sent to the grid for consumption by others. You are effectively selling excess electricity as per tariffs. This process is automated and taken care of by the net-metering process.
Net-Metering is a two-way meter will be used to calculate the amount of electricity consumed from the grid that you consumed and the amount of excess electricity generated by the consumer that was sent back to the grid. The difference will be adjusted in the next billing cycle.