Metering

Energy meter is a very important tool to record energy in kWh consumed by the load. In grid-connected system energy meter is also used to record the amount of energy produced by PV array. There are three methods of metering used in PV-grid system:

1. Single net meter. This is a bi-directional energy meter. It just required one unit to be installed. The meter will show the net power consumed at the end of every month. However, this technique will not record the total amount of energy being generated by the PV power generator. 
2. One import meter and one export meter. Each meter is a unidirectional energy meter and both are connected in series. The import meter will record the total energy consumed and the export meter will record total energy being generated to the grid separately. Although the export meter enable to record the total export enegy, this method cannot differentiate between energy generated from the PV array and other resources e.g regenerative energy from the machine operation.
3. Dedicated export meter. This is a uni-directional energy meter that record the energy produced by the PV array and feed the grid separately.