While solar power installed in the country is about 50GW and contributes to about 8-10% of energy injected into the grid. The impact is significant in the grid in terms of grid stability due to the variable nature of this generation source. In the states like Gujarat, Tamilnadu, and Karnataka, the highest daily share of solar and wind is over 70%. On an annual basis, solar and wind contribute over 30% of energy in these states. Hence the impact of variable generation on grid stability is a concern that the regulators are having a big concern. While we are considering 500 GW of renewables by 2030, the interstate grid interconnections need to be taken in mission mode. If we are not able to achieve grid flexibility, it may lead to curtailment and will impact the profitability of generators.
While solar and wind power are cheaper, in order to absorb the low-cost power, the Discoms have to back down the conventional power plants, and have to pay the fixed charges due to their long terms PPA obligations. This impacts the profitability of Discoms, and some of the states move slowly in adopting renewable power. On account of grid stability, Karnataka has to curtail about 10-25% of both solar and wind to attain grid stability. This curtailment can increase further if the grid flexibility is not addressed.
As per one of the IEA analysis in the context of Gujarat, most effective grid flexibility can be achieved through agricultural demand response and battery storage systems in the grid. With a combination of 4 GW battery storage, pumped hydro, and agricultural demand response, the curtailments can be brought down to 2% by 2030.
There is a trend in increasing variability in daily demand. While the hourly demand variability was about +/- 8 GW in 208, it has increased to the tune of +14GW and -10GW in 2018, as per the recent Niti Aayog report. On a typical day in India conventional generation needs to back down in the morning between 8:00 and 12:00, followed by an increasingly steep ramp-up between 14:00 and 19:00. As we can see the typical all India load profile, the ramp up and ramp down needs of conventional power plants has increased significantly. There is an urgent need to address this, otherwise the technical challenges will curtail the investment flow in Indian power sector.