Net metering
Net metering is a billing arrangement for a rooftop solar system in which the electricity a consumer exports to the grid is subtracted from the electricity they import. Only the difference is billed, or credited, at the normal retail tariff, using one meter that records flow in both directions.
The definition comes from the Electricity (Rights of Consumers) Amendment Rules, 2021, notified by the Ministry of Power on 28 June 2021 as G.S.R. 448(E). The rules call a consumer who also generates power a prosumer.
The same rules describe two alternatives. Under net billing, also called net feed-in, exports and imports are valued at two different tariffs: a feed-in tariff for what is exported and the retail tariff for what is imported. Under gross metering, all the solar output is sold at a feed-in tariff and all consumption is billed separately.
The details are set by each State Electricity Regulatory Commission. Where a state's regulations do not provide for it, the 2021 amendment lets the commission allow net metering for loads up to 500 kilowatts or the sanctioned load, whichever is lower.