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Tamil Nadu Revises Wind Repowering Policy to Improve Viability of Ageing Projects

The Tamil Nadu Energy Department has revised key provisions of its Repowering, Refurbishment, and Life Extension Policy for Wind Power Projects, originally notified in 2024, with the aim of making upgrades to ageing wind assets more practical and financially attractive.

The updated framework introduces greater clarity and flexibility across eligibility timelines, generation benchmarks, development charges, certification norms, banking provisions, and operational conditions. These changes are intended to encourage repowering and life extension of older wind turbines while reflecting advancements in turbine technology and evolving grid requirements.

Revised Eligibility Timelines
Under the earlier policy, all wind energy generators (WEGs) connected to the state transmission utility were required to opt for repowering, refurbishment, or life extension upon completing 20 years of operation, irrespective of commissioning date. The revised provision differentiates projects based on commissioning timelines. WEGs commissioned before April 1, 2016, will continue to be required to opt for intervention after 20 years. However, projects commissioned on or after that date may operate for up to 25 years before repowering or life extension becomes mandatory. This change acknowledges improvements in turbine design life and avoids premature intervention in relatively newer installations.

Relaxed Performance Criteria for Life Extension
Previously, turbines seeking life extension after 20 years were required to demonstrate average generation of at least 90% of rated capacity over the preceding three financial years. The amended guideline lowers this threshold to 70%, subject to certification by the National Institute of Wind Energy (NIWE) or another independent agency. The revision recognizes natural performance degradation over time while ensuring that technically sound turbines remain eligible for life extension.

Updated Generation Benchmarks
Earlier eligibility for repowering or life extension depended on achieving fixed numerical multipliers—ranging from 1.1 to 1.25 times the average generation of the existing turbines over the previous three years. The amended policy replaces this rigid approach with a pro rata assessment linked to the repowered capacity, rather than the original installed capacity. The focus now shifts to incremental generation as a benchmark, offering developers greater flexibility, particularly at wind-saturated or low-wind sites.

Rationalised Development Charges
The previous framework required developers to pay a development charge of Rs 3 million per MW on the entire wind capacity, even when only partial repowering was undertaken. Under the revised policy, the Rs 3 million per MW charge applies only to the incremental repowered capacity, while a significantly lower charge of Rs 500,000 per MW is levied on the existing capacity. This revision substantially reduces upfront costs and removes a major financial hurdle for repowering projects.

Simplified Certification Requirements
Earlier, turbines undergoing life extension or repowering were required to obtain certification from accredited agencies in line with UL 4143 or Bureau of Indian Standards (BIS) benchmarks, along with a new or extended type certificate. The amended clause simplifies this process by allowing structural integrity certification from the original equipment manufacturer (OEM) or a certified chartered civil engineer, while electrical safety certification must be obtained from the Chief Electrical Inspector to the Government.

Clarification on Existing Power Purchase Agreements
The policy earlier allowed WEGs opting for repowering or life extension to continue supplying power under their existing power purchase agreements (PPAs) until expiry. The revised clause clarifies that this continuity applies only to the existing generation capacity. After PPA expiry, generators must either enter into a new PPA, sell power through energy wheeling arrangements, or accept a tariff determined by the state regulator—whichever is lower.

Revised Banking Provisions
The earlier banking framework limited banking to the May–September wind season, with slot-wise restrictions, minimum monthly utilization conditions, and fixed banking charges in kind. The updated policy aligns banking with the financial year (April–March), allows slot-to-slot utilization, including the use of peak energy during off-peak hours, and links accounting and charges to Tamil Nadu Electricity Regulatory Commission (TNERC) regulations. Any unutilized surplus banked energy will be compensated at 75% of the tariff fixed by TNERC.

Updated Fall Distance Norms
Earlier regulations mandated a fixed 500-metre setback from dwellings. The amended policy introduces a formula-based approach—hub height plus half the rotor diameter plus 5 metres—subject to implementation of adequate noise mitigation measures. This relaxation does not apply to projects seeking life extension or refurbishment without changes to hub height or rotor diameter.

Expanded Must-Run Status for Hybrids
While the original policy allowed conversion of wind projects into wind–solar hybrids, solar generation did not enjoy must-run status during the wind season. The revised guidelines permit projects undergoing repowering, refurbishment, or life extension to convert into wind–solar hybrids, granting must-run status to combined generation up to the approved evacuation capacity, even during the wind season.

India added 6.3 GW of wind capacity in 2025, marking an 85.2% year-on-year increase, according to Mercom India Research—the highest annual wind additions recorded in the country. The improved policy environment, alongside increased tender activity and competitive tariffs, is expected to further support wind sector growth in Tamil Nadu despite ongoing challenges related to land acquisition and grid connectivity.