Solar Net meter or Bi-directional meter is an electric meter approved and issued by DISCOM to senses the flowing current and stores the total consumption units.
Traditional energy meter is a uni-directional meter. it runs only in forward direction regardless whether an export or import is being happening.
Unfortunately it increases the meter reading for the export units as import. Means its not reducing your electricity bill but charging extra for your export units.
Solar Net Meter or Bi-Directional meter recognize the dual current flowing directions and records the consumption data. Generally In daytime maximum loads are not active hence excess generating energy will feed back into the grid Called "Export".
In this scenario, current flowing direction is reverse and Net meter records the export units data. During nights, solar generation becomes zero and system starts importing electricity from the grid to operate the loads. Here the current flowing direction is forward and recorded units are called as "Import".
At the end of every month, electricity billing will generated based on consumed “Net Units”( import units will deduct from export units) only. surplus units will carry forward to the next month billing.