Day to day basis the demand of electricity is going up as compared to generation capacity. To meet the increased demand, our government is promoting different sources of clean or renewable power resources – like wind, solar, water etc. But special focus has been given on solar power (roof top) due to its easiest, simplified, safer & economical characteristics for domestic as well as commercial consumers – for decreasing the demand of electricity from grids as well as reducing their electricity bills.
Keeping that in view, the commission is mandated to promote co-generation and generation of electricity from renewable sources of energy by providing suitable measures for connectivity with the grid – and sale of electricity to any person under Section 86 (e) of the Electricity Act, 2003. Two amendments have been done in 2015 on electricity act relating to Net-metering/ Bi-directional metering for solar generation projects including their LT connectivity for Government/ PSU owned and other buildings.
There are two arrangements that have been defined by the government, when designing the regulations for solar rooftop systems – Gross metering and Net metering.
The Union Ministry of Power may allow net metering to the prosumer (already having electricity connection) for up to 500 kilowatts (kW) or up to the sanctioned load, according to the amendment in the Electricity (Rights of Consumers) Amendment Rules, 2021.
Net metering is basically for domestic or commercial consumers having sanction load from 1 kW to 500 kW.
The Net metering is a programming mechanism in meter, either static or smart meter, which measures the export energy (energy received from Utility) and import energy (energy supply to grid/DISCOM) – and provides the NET energy. The NET metering is also called Bi-directional metering as it records export as well as import energy to reduce electricity bills.
The user consumes electricity generated by the rooftop solar system and excess electricity is injected into the grid (DISCOM / Utility). For any additional requirement over and above the solar generation, energy can be imported from the grid. At the end of the settlement period, the consumer pays for the difference between solar energy supplied to the grid and the total energy drawn from the grid.
In net metering, the consumer is billed for the “net” energy that is used, which is the difference between total energy produced by the solar system and total energy consumed. Net metering calculates the difference of excess power exported back to the grid and total power consumed by the user. Hence, the surplus energy earns revenue while the shortage of energy is covered by the grid.
There is some difference in NET metering in India, each state can have different regulations for the type of net meter used to record the power. Some states require only one meter to measure the net amount of power consumed by the user. Whereas, other states require two meters to record the total amount of units consumed by the owner from the grid along with the total amount of power generated by the owner’s system.
Gross metering is an arrangement in which a consumer is compensated at a fixed feed-in-tariff for the total number of units of solar energy generated and exported to the grid (accounted by a unidirectional ‘gross meter’) and has to pay the electricity distribution company (DISCOM) at retail supply tariff for the electricity consumed from the grid. The feed-in-tariff and retail supply tariff are typically different rates.
The minimum solar power capacity required to avail gross metering is 10kW. It is ideal for those businesses and private developers that install solar plants, not for self-consumption but for the sale of energy.
- Case: 1 (Net metering) – Consumer pays for the net energy consumed from the grid at a retail tariff of 9 per kWh and gets compensated at APPPC (Average Pool Power Purchase Cost), which is Rs. 4 per kWh for injection into the grid (if any).
- Case: 2 (Gross metering) – Consumer gets compensated at APPPC for total energy injected into, and purchases power from DISCOM at a much higher retail tariff.
In gross-metering, consumer needs to purchase total energy for consumption at retail tariff, which is generally higher than the Feed-In-Tariff (FIT) while in net metering, since import of power is adjusted against export, the consumer avails equivalent reduction in his/her electricity bill.
Dheeraj Mehta, an engineering graduate, is a techno-commercial professional with 26 years of experience in power distribution. He is an expert in the fields of metering, AMI, energy audit, testing and billing. Presently he is working in Tata Power Odisha (Northern DISCOM) as a Group Head of meter management & AMI cell. He had also tackled power distribution challenges in metro cities like Delhi, Agra, Nagpur etc., when he was associated with Reliance Infra Ltd., BSES, Torrent Power Ltd., and Spenco Ltd.
