Tamil Nadu’s Energy Department has amended key provisions of its Repowering, Refurbishment, and Life Extension Policy for Wind Power Projects, which was issued in 2024.

The revised clauses introduce greater flexibility in eligibility timelines, performance benchmarks, cost structures, certification requirements, and operational norms, with the objective of making repowering and life extension of ageing wind projects more viable in the state.

Eligibility for Repowering and Refurbishment

Under the earlier policy, all wind energy generators (WEGs) connected to the state transmission utility (STU) were eligible, but it was mandatory for turbines that had completed 20 years of operation to opt for repowering, refurbishment, or life extension, regardless of when they were commissioned.

Under the modified clause, WEGs commissioned before April 1, 2016, must opt for repowering, refurbishment, or life extension after 20 years, but those commissioned on or after that date can continue operating up to 25 years before being required to do so. This change recognizes improvements in turbine technology and design life over time, and avoids forcing relatively newer machines into premature intervention.

Earlier, turbines seeking life extension after completing 20 years had to demonstrate that their average generation over the previous three financial years was at least 90% of rated generation. The modified provision relaxes this threshold to 70%, based on certification from the National Institute of Wind Energy or another independent agency. This acknowledges natural performance degradation over time and ensures that technically sound but moderately underperforming turbines are not excluded from life extension options.

Annual Generation Benchmark

Earlier, eligibility for repowering or life extension was tied to strict numerical thresholds—projects had to demonstrate an increase of at least 1.1 times to 1.25 times the average generation of the last three years of the existing WEGs.

The amended clause introduces a pro rata assessment linked to repowered capacity rather than the old installed capacity. The increase in generation now serves as a benchmark for evaluation, providing developers with flexibility, particularly at wind-saturated or low-wind sites, where achieving fixed multipliers was often impractical.

Development Charges

Previously, developers were required to pay a development charge of ₹3 million (~$32,785)/MW for the entire wind generation capacity, even if only part of it was upgraded. The revised clause applies the ₹3 million (~32,785)/MW charge only to the incremental repowered capacity, while imposing a much lower nominal charge of ₹500,000 (~$546.42)/MW on the existing capacity. This substantially reduces upfront costs and removes a major financial barrier to repowering projects.

Certification

The earlier policy required turbine assessment and certification by accredited agencies in accordance with UL 4143 or the Bureau of Indian Standards (BIS) benchmarks, along with the issuance of a new or extended type certificate.

The modified clause simplifies this process by allowing structural integrity certification by the original equipment manufacturer (OEM) or a certified chartered engineer (civil), while mandating electrical safety certification from the Chief Electrical Inspector to the Government.

Continuity of Existing PPAs

Previously, WEGs opting for repowering, refurbishment, or life extension could continue supplying power under their existing power purchase agreements (PPAs) until the end of the agreement term.

The amended clause clarifies that this continuation applies only to the existing generation capacity. Once the PPA expires, the generator must either enter into a PPA, sell power through an energy wheeling agreement, or accept a tariff fixed by the state regulator, whichever is lower.

Annual banking arrangements

The earlier framework limited banking to the May–September period, imposing slot-wise caps, minimum utilization conditions, and fixed banking charges in kind.

Annual banking was allowed for the same financial year, subject to the condition that 50% of the generation happened during the wind months (May to September).

The earlier clause stated that slot-wise energy utilization was allowed for the period from October 1 to March 31. Also, the minimum utilization was expected not to exceed 20% of the net banked energy each month from October 1 to December 31. Additionally, the WEGs were to be charged 16% of the banked energy as banking charges in accordance with the revision every year.

The revised clause aligns banking with the financial year (April to March), allowing slot-to-slot utilization, including the use of peak energy during off-peak hours, and linking accounting and charges to the Tamil Nadu Electricity Regulatory Commission’s (TNERC) regulations. As per the modified clause, any surplus unutilized banked energy would be paid at 75% of the tariff fixed by TNERC.

Fall Distance Norms

The fall distance refers to the safety setback distance from structures, calculated to prevent damage from wind turbine collapse.

Earlier, wind projects were required to maintain a fixed setback distance of 500 metres from dwellings, with limited scope for relaxation.

The amended clause introduces a formula-based approach—hub height plus half the rotor diameter plus 5 metres—subject to implementation of adequate noise mitigation measures. However, this relaxation does not apply to projects seeking simple life extension or refurbishment without changes in hub height or rotor diameter.

Must-run Status

Under the original policy, conversion of wind projects into wind–solar hybrids was permitted, but solar generation did not have must-run status during the wind season (May to September).

The modified clause allows developers undertaking repowering, refurbishment, or life extension to convert to wind–solar hybrid projects. It extends must-run status to combined wind–solar generation up to the approved evacuation capacity, even during the wind season (May to September).

India added 6.3 GW of wind power capacity in 2025, an 85.2% YoY increase from 3.4 GW in 2024, according to Mercom India Research. The additions marked the highest annual wind installations recorded in the country. India’s wind power market improved in 2025, supported by higher tender activity, stronger bidder participation, and more competitive tariffs. While land acquisition and grid connectivity remain challenges, developers are addressing these issues, helping keep projects on track for commissioning.