Net-metering is a system through which your electricity units are calculated by subtracting the number of units you feed back to the grid from the total number of units you consume from the grid. Your solar system generates electricity units, which if used, reduce the electricity import from the grid thereby reducing your total count of grid units consumed, and, if not used, are fed back to the grid, which reflects in your electricity bill as a reduction in the number of units consumed. We have a unidirectional electricity meter installed in our homes. A net-meter is a bidirectional meter which moves according to the grid units being imported and exported to the grid.
How does it work?
The net-meter takes into account the solar units generated, consumed by the user, exported to the grid and units imported from the grid. Let’s take an example for a user who consumes around 700 units per month and his typical electricity bill of a month was Rs. 5600 before installing a solar plant. The consumer sets up a 5kW solar plant which generates around 600 units per month. The consumer is out during the daytime on weekdays and hence, cannot directly consume all the solar units generated by the plant. Let’s see how can the consumer benefit from net-metering:
| Monthly units consumed | 700 units |
| Monthly Solar Units | 600 units |
| Solar units consumed | 300 units |
| Balance Solar Units exported to the grid (e) | 300 units (600 – 300) |
| Units imported from the grid (i) | 400 units (700 – 300) |
The number of units imported from the grid is more than the solar units exported to the grid (i>e), the bi-directional meter reads the number of billable units for the consumer as 100 units (i – e). The bill is now Rs.800, a net saving of Rs. 4900 per month!
The consumer exports more solar units than imported:
Let’s take an extension of the above example: the consumer has gone for a holiday while the solar system is running. The total number of units consumed this month is 400. Of this, the customer imports 300 units from the grid (i) while 100 solar units are consumed. The balance of 500 solar units are exported to the grid (e). In this example, the number of solar units exported to the grid is more than the number of units imported from the grid (e>i). The net bill of consumer, as computed by the bi-directional meter will be -200 units. At times, this is shown as a negative bill by the DISCOM. These excess units will be carried forward to the next month’s billing cycle or he/she will receive credits for excess units (credit value vary from state to state depending on the policy and per unit rate decided).
Liaising and Documentation
Certain approvals are required for net metering. These approvals vary from state to state and based on the type of installation and system size. You may refer to the links for Net Metering Policies which would vary state to state:
- https://mnre.gov.in/file-manager/UserFiles/Grid-Connected-Solar-Rooftop-policy/UPERC-Rooftop-Solar-PV-Regulations-2015.pdf
- https://www.bsesdelhi.com/web/brpl/net-metering
- https://bit.ly/2Ivioyl
Permits and approvals required are given below:
- Interconnection permission from your power distribution agency (DISCOM)
- CEIG’s (Chief Electrical Inspector to the Government of state) permission (pre & post-installation) as applicable. (in case of 10kW and above)
Permission and Approval process for grid-connected system under Net Metering :
- Submission of application to the local distribution company (DISCOM) with project details and required permit fee.
- The distribution company will conduct a feasibility analysis of the Project Site. Distribution Company will approve or reject the proposal based on the report.
- After the distribution company (DISCOM) approval, an application is to be submitted to the DISCOM for registration of the rooftop project.
- Interconnection agreement is signed by the consumer and the DISCOM.
Liaising and facilitation for net metering will be executed by HomeScape team. However, one-time fee for commissioning net meter may come in customer’s scope (which would be charged as per the DISCOM policies for different states).
