How it works
The green day-ahead market shares its bidding window with the conventional day-ahead market on the same exchange. Renewable sellers offer power for each fifteen-minute block of the next day, and buyers bid for green supply, both as pairs of price and volume in MW. Sellers must show the power comes from eligible renewable sources. Buyers include distribution utilities, open-access consumers and traders.
When the window closes, the exchange clears the green book first, block by block, at its own clearing price. Green sell bids that do not clear can then move into the conventional day-ahead auction, if the seller has chosen that option. The conventional market then clears with those extra offers in its stack. Cleared green volumes are scheduled through Grid-India and the state load despatch centres like any other exchange trade. The energy counts towards the buyer's renewable purchase obligation, so no separate certificate is issued for it.
Why it matters
For a renewable IPP with uncontracted capacity, the green market is a second outlet. It can pay a premium over the conventional price, because buyers with obligations value the green attribute. Unsold bids can roll into the conventional auction, so offering green first carries little downside. For an industrial buyer, it is a short-notice way to buy renewable power that counts towards its obligation, without signing a long-term contract.
A worked example
A 30 MW solar plant offers 24 MW for the 12:00–12:15 block in the green market at ₹2.50/kWh. The block clears at ₹3.20/kWh. The energy is 24 MW × 0.25 h = 6 MWh, or 6,000 kWh, so revenue is 6,000 × ₹3.20 = ₹19,200. Sold in the conventional market at ₹2.80/kWh, the same block would have earned 6,000 × ₹2.80 = ₹16,800. The green premium is ₹2,400.
Illustrative figures.
Across markets
A separate green day-ahead auction is specific to India, run on IEX and the other power exchanges under CERC approval. In Europe and the US, renewable and conventional power clear in the same auction at the same price. Buyers who want green supply contract for it directly, or pair market power with certificates, such as guarantees of origin in Europe or RECs in the US.