Nearly all of India’s major wind states, such as Tamil Nadu, Gujarat, Rajasthan, Karnataka and Maharashtra, also have good solar potential. When sited individually, wind and solar projects are allocated a transmission capacity equivalent to their rated capacity, resulting in an underuse of the transmission capacity, as both wind and solar do not generate at their rated capacity for a majority of the time.
In contrast, if the projects are designed to co-generate, the allocated transmission capacity can support a higher-capacity hybrid project. Fluctuations in wind and solar generation throughout the day and seasons suggest great complementarity — wind generation peaks when solar generation is low and vice versa — across the region. Taking these factors into consideration, hybridisation can help achieve better load management, transmission capacity allocation and land utilisation.
Recognising the potential, the Ministry of New and Renewable Energy, had released a draft wind-solar hybrid policy in 2016, which was passed in May 2018. The policy suggests going for a tariff-based transparent bidding process. The policy also allows for hybridisation of operating wind projects with solar PV or the other way round. Many states have subsequently released their own wind-solar hybrid policy.
After the policy was announced, the Solar Energy Corporation of India (SECI) launched a 2.5GW wind-solar hybrid tender in June, with a ceiling tariff of INR 2.93/kWh in June 2018 due for award this month after the deadline was extended from 8 August.
Regen Powertech combined a 1.5MW commercial wind turbine with 200kW of solar PV as far back as 2014. More recently, in April 2018, Hero Future Energies, one of the largest renewable-power producers in India, partnered with Siemens Gamesa Renewable Energy (SGRE) to add 28.8MW of solar PV capacity to an operational 50MW wind farm without augmenting the grid connection capacity to demonstrate optimisation of transmission capacities.
In August, SGRE commissioned a small hybrid pilot for the National Thermal Power Corporation, India’s largest thermal power generator, by combining a 2MW turbine with a 1.375MW high-efficiency HiT solar panel.
Amid the recent lull in wind tenders due to grid-access issues, wind-solar hybrids could help revive an industry that has to grow nearly twofold in the next three years.