The proposal requires at least 10% equivalent battery storage output to generation capacity. For an initial 400MW auction, therefore, a 10% BESS requirement would correspond to around 40MW/160MWh of energy storage. BESS would charge during high daytime variable renewable energy (VRE) hours and discharge during higher net-demand hours. This would reduce the evening ramp and recover curtailed energy.
ISMO said its modelling of IRRs from solar, wind and co-located renewables with 10%, 20% and 25% BESS showed projects remain feasible and competitive. The first auction tranche had been planned for 200MW, but a doubling of target capacity was approved by the Ministry of Energy’s Power Division in July.
Mandatory BESS is “prudent and proportionate,” according to ISMO, because the increasing share of VRE is already creating duck curve, ramping and curtailment challenges for the grid.
Power sector expert Rehan Javed, among the stakeholders invited to comment, supported the mandatory co-location of BESS with wind and solar project bids, but suggested a higher threshold of 15% to 20% may be more effective in meeting the auction’s aims. The National Energy Academic Network (NEAN) also questioned why the ambition was not higher, given that consultation responses appeared to support a 20% threshold.
