There are basically two types of Solar Photo Voltaic (PV) (Roof top / Ground Mounted) Grid Tied Metering system : –
1) Net Metering System
2) Gross metering
Here I am going to discuss the first one i.e. Net Metering System. In this system, after installing the Grid Tied PV System in its premises over the Roof Top or Ground Mounted , Solar power plant starts generating the Electrical Power / Electrical Energy. This Energy could be used by the customer itself (as a whole) or if Unused / Surplus Power exists, it may be exported to the Grid.
For this Discom (Distribution Companies) install 2 Nos. Meters :-
1) A Unidirectional Energy Meter for Solar Energy , Which measures the Energy generated by Solar Plant
2) A Bidirectional Energy Meter which Registers the Energy imported from the Grid & Excess Generated Solar Exported to the Grid.
The number of Units exported to the grid are carried forward month after month and can be utilized by the consumer any time within a financial year. If the exported number of units are not used by the consumer then at the end of the Financial year, the Discom would pay for the same at the Pre- decided Rates (Any Where from INR 3 to INR 8 per units) as prescribed by the local Discoms from time to time. These Payments rates may vary from States to states. The Net Metering policy varies from State to State and is presently limited upto 1 MW Plant Capacity. It may be applicable to Residential , Commercial, Industrial & Farming Pumps as per the State Policies.