Where DF is not possible for any reason, the IF configuration is chosen.
In IF the PV generated electricity is fed into the customer’s internal wiring at the main distribution board (MDB) or a sub-distribution board (DB) on the user side of the TNB supply meter and the PV meter may be installed beside an MDB or DB.
The PV generated electricity is therefore first used by the consumer and only excess electricity generated is fed into the TNB network. In this case the PV system can be connected to the user’s wiring network as soon as it is installed. The wiring connection for such a configuration is as shown by the sketch below.
As electricity flow is bidirectional for customer import and export, the TNB meter would need to record both “import and export” electricity and needs to be an “Import-Export” meter. The GCPV system owner shall be required to pay the cost of the “Import-Export” meter to replace the uni-directional meter that TNB installs as a normal practice. The uni-directional meter normally supplied by TNB at its cost can become the PV meter.
In this configuration, the PV meter still records the total electricity that is generated by the GCPV system and fed into the TNB network, but the TNB supply meter records both the net electricity consumption of the customer and the surplus electricity exported through the meter to the TNB grid.
The net-metering for billing in this case is the difference between the electricity supplied to the customer through the TNB meter measurement in the import mode, and the surplus PV generated electricity exported to the TNB grid and recorded by the TNB meter in the export mode. The PV meter still records the electricity generated by the PV system.