How Solar Net-Metering works?
In grid-connected Solar PV systems, the DC output generated by the solar panels is converted into AC (alternating current) output by a solar inverter. This output, from the solar inverter, called solar energy, is connected to the distribution board or switch board of the building or the home and is then consumed by the electrical appliances. If the solar energy produced is more than what the loads in the building or home consume, the surplus solar energy is automatically exported (energy export) to the DISCOM distribution network (the grid) with the help of a two-way meter. If the solar energy produced is less than the total energy required in the building, then the shortfall energy is automatically supplied by the grid (energy import).
Bidirectional energy meter
In order to implement net-metering, your existing energy meter would need to be replaced with a bidirectional (two-way) energy meter. This bidirectional energy meter can measure both, energy import (from the grid to the consumer) and energy export (from the consumer to the grid). These meters are also called import-export energy meters.
Electricity Bill with Solar net-metering
Under solar net-metering, the Consumer only pays for the difference in energy imported and the energy exported. If a Consumer imports 1000 kWh in June billing period and exports 600 kWh in the same period, the Consumer will be charged for only 400kWh. If the import energy in the July period is 500 kWh and the export again is 600kWh, then the excess 100kWh will be carried over to the next month's bill or next billing cycle and adjusted there. At the end of the Settlement period (usually 12 months period), any balance and unadjusted carried forward excess export will be paid to the Consumer at a pre-defined tariff (rate/kWh), which will be notified time to time by the relevant authorities.
(A case for a Delhi-based School open 6 days/week having monthly electricity bill of Rs 2 lacs sets up a 60kW Solar PV system)
|(A)||Monthly Energy consumption (Import from Grid)||: 16,500 units (kWh)|
|(B)||Monthly Solar energy generation(Solar energy consumed by School||: 7,800 units|
|(C)||Balance solar energy (Exported to Grid)||: 1,115 units (7,800 - 6,685)|
|(D)||New Monthly import from grid||: 9,815 units (16,500 - 6,685)|
As the net import
export, the net billable units = 8,700 (16,500 - 6,685 - 1,115) leading to a reduced monthly energy bill of Rs. 1,13,030, which is a saving of Rs. 86,970 per month.
Had export been greater than the import, the difference would have been carried forward to the next billing cycle. Any unadjusted units are paid only at the end of the settlement period at the APPC rate, which currently is Rs. 4.30 for Delhi.
Additionally, this Delhi school is also entitled to be paid an incentive for the monthly solar generation at a rate of Rs 2 per unit under the Generation Based Incentive scheme, which would mean another reduction of Rs 15,600, effectively reducing the monthly energy bill to Rs 97,430 from the current number of Rs 2,00,000.
|Category||Existing Electricity Connection||With Solar Net Metering|
|Monthly Import from grid (units or kWh)||16,500||9,815|
|Net billable units||16,500||8,700|
|Grid Electricity Bill||2,00,000||1,13,030|
|Generation Based Incentive* (Rs)||N.A.||15,600|
|Grid Electricity Bill after Incentive (Rs)||2,00,000||97,430|
Net-metering / Gross-metering Highlights in Delhi
|Net metering or Gross metering||Net metering||Only Net Metering policy is applicable|
|Applicable pre-vailing |
APPC rate (Rs./kWh)
|4.30||APPC rate prevailing at the time of |
Selltelemt will be applicable
|Adjustment at the end of settlement |
period for any unadjusted units
|APPC rate||APPC rate prevailing at the time of |
Selltelemt will be applicable
|Solar System size (kW)|| Min 1 kWp; Max 1000 kWp|
|Max Solar System size based on |
sanctioned load (kW)
|=100%||Sanctioned load 5kW, then max |
Solar System size 4kW
|Discom cumulative capacity of local |
|LT - 15% ; HT - 30%||LT - 15% ; HT - 30%|
|Capping of Solar generation||Not applicable||Not applicable|
|Incentive (Rs./kWh generated) for 2 years for |
domestic net metered connections (Rs/kWh)*
*A Generation Based Incentive (GBI) incentive of Rs. 2.00 per unit will be paid to Consumer on gross solar energy generated from his rooftop system for next 3 years (till 2018). The minimum eligibility criteria for GBI will be 1,100 solar energy units (kWh) generated per annum per kWp. For solar plants that generate less than 1,100 units (kWh) per kWp a year, the GBI facility will not apply. The annual solar energy generation that is eligible for GBI shall be capped at 1,500 kWh per kWp, irrespective of the readings of the solar generation meter.
Towards the end of this period, the State shall consider extending the GBI for an additional two years depending on the economics of solar energy, grid tariffs, and solar energy adoption rates in the domestic segment.
View the Delhi Solar Policy here and the Delhi Net-Metering Policy here
Why Every Resident of Delhi Should Look to Go With Rooftop Solar Now
Why Now is the Best Time to Invest in a Solar PV System in Delhi