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					</table>Wind turbine manufacturer Vayona Energy has signed an agreement with independent power producer <a href="https://www.oysterrenewable.com/" target="_blank" rel="noopener">Oyster Renewable Energy</a> to supply 64.8 MW of its 18 SG 3.6-145 wind turbines for a project in Kadapa, Andhra Pradesh.
Vayona will also provide long-term operations and maintenance (O&amp;M) services for the turbines.
The wind turbines have a capacity of 3.6 MW each.
Vayona was <a href="https://www.mercomindia.com/tpg-and-mavco-form-vayona-energy-for-wind-turbine-manufacturing" target="_blank" rel="noopener">formed</a> in late 2025 as an independent wind energy platform by global alternative asset management firm TPG and a MAVCO-led consortium, following the <a href="https://www.mercomindia.com/tpg-acquires-siemens-gamesas-india-and-sri-lanka-wind-businesses" target="_blank" rel="noopener">acquisition</a> of Siemens Gamesa&#8217;s onshore wind business in India and Sri Lanka.
The company stated that it has a customer order book and an O&amp;M portfolio of approximately 7 GW.
Vayona’s SG 3.6-145 and other similar-capacity wind turbines have secured an order intake exceeding 3.6 GW since their launch in India. The order intake surpassed 2 GW in December 2025.
Critical components of these wind turbines will be manufactured at Vayona’s facilities in Mamandur, Tamil Nadu. The turbine supply is scheduled to commence from the first quarter of 2026. 
The company has a wind portfolio of approximately 12 GW in operational and development assets.
India <a href="https://www.mercomindia.com/india-records-highest-ever-wind-capacity-additions-at-6-3-gw-in-2025" target="_blank" rel="noopener">added</a> 6.3 GW of wind power capacity in 2025, an 85.2% year-over-year (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. Andhra Pradesh installed 4.3 GW of wind energy during the year.
India installed 1.38 GW of wind energy capacity in the fourth quarter of 2025, a 73% YoY growth from 800 MW in Q4 2024. Capacity additions were down 4% in a quarter-over-quarter comparison.
Last year, the Ministry of New and Renewable Energy <a href="https://www.mercomindia.com/mnre-mandates-wind-turbine-prototype-testing-in-india-from-2027" target="_blank" rel="noopener">amended</a> the standard operating procedure (SOP) for prototype testing under the Approved List of Models and Manufacturers (ALMM) for wind and wind turbine components, while the SOPs were <a href="https://www.mercomindia.com/mnre-issues-standard-operating-procedure-for-almm-wind-turbine-enlistment" target="_blank" rel="noopener">issued</a> in October. For a wind turbine model to qualify under ALMM (Wind), it must possess a valid type certificate issued by an accredited certification body.

Vayona to Supply 65 MW of Wind Turbines to Oyster Renewable

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					</table>For nearly a decade, India’s interstate transmission system (ISTS) charges waiver has quietly shaped renewable power economics. By lowering landed tariffs on interstate sales, it encouraged the adoption of corporate open access and gave developers the confidence to scale. That cushion is now disappearing. The full waiver for solar and onshore wind expired on June 30, 2025, and has been replaced with a phased taper that will run until June 30, 2028.
The new framework <a href="https://www.mercomindia.com/no-ists-charges-waiver-solar-wind-june-2028" target="_blank" rel="noopener">reduces</a> charges by 75% in the financial year (FY) 2026, 50% in FY 2027, and 25% in FY 2028 before complete withdrawal. Developers and offtakers are now weighing how this shift will alter tariffs, project viability, and long-term growth in a sector that leaned heavily on waiver-driven competitiveness.
Tariff Impacts 
Industry leaders are split on how much the tapering will affect tariffs. Some argue it has no direct bearing on discovered prices, while others warn it will push landed costs higher and dampen demand.
Rahul Mishra, Senior VP and Head of C&amp;I Business at <a href="https://blupineenergy.com/" target="_blank" rel="noopener">BluPine Energy</a>, believes that competitive bidding shields tariffs from transmission charges. Since bids are placed at the grid substation level, transmission costs are not factored into the quoted price.
He feels efficiency in capital deployment, technology, and execution discipline matter far more than transmission dynamics.
Others see the reality differently. Sanjeev Gupta, Director – Technical and Projects at <a href="https://hartek.com/" target="_blank" rel="noopener">Hartek Group</a>, pointed out that the full waiver effectively lowered landed tariffs by ₹0.40 (~$0.00457)/kWh to ₹0.50 (~$0.00571)/kWh. With tapering, he expects tariffs for distribution companies (DISCOMs) and corporate buyers to climb, which could strain procurement in a price-sensitive market.
Siddharth Bhatia, Managing Director at <a href="https://www.oysterrenewable.com/" target="_blank" rel="noopener">Oyster Renewables</a>, added that once the waiver is fully withdrawn, renewable power supplied through the grid could cost ₹0.80 (~$0.00914)/kWh to ₹1 (~$0.01143)/kWh more. While operational efficiencies and contract arrangements may offset some of the increase, buyers would still see higher bills overall.
The contrasting views highlight a deeper divide: tender tariffs may not formally reflect transmission costs, but landed prices at the buyer’s end do. Gupta warned, “Under the 75%, 50%, and 25% phase-down, tariffs could move upwards by 8% to 12%,” a level that could influence demand in states with strict tariff caps.
Deadline Pressure 
The phase-down has triggered a wave of accelerated project execution. Developers across the sector pushed capacity forward to meet waiver-linked commissioning deadlines.
BluPine fast-tracked projects to align with the June 2025 cutoff and sought the Ministry of New and Renewable Energy-backed extensions in cases where land clearances, supply disruptions, or force majeure held things up.
Oyster Renewables adopted a similar approach, front-loading parts of its pipeline to maintain tariff competitiveness for DISCOMs and commercial and industrial buyers, while documenting bottlenecks, such as land acquisition delays or module import slowdowns, to justify extensions. Hartek moved aggressively to speed up nearly a third of its planned pipeline.
The net effect has been a sector-wide rush to deliver, driven not only by market economics but by regulatory timelines that have left little room for slippage.
Rethinking Siting Strategies
The taper is also pushing companies to rethink where they build. BluPine is already shifting its attention to within-state, state transmission utility-connected projects for corporate buyers, viewing them as a means to retain competitiveness once interstate transmission charges fully return after 2028.
Mishra noted that factors such as falling equipment prices and efficiency gains could eventually help absorb transmission costs. Still, in-state siting provides an added layer of cost stability for clients.
Oyster Renewables is taking a dual approach. The company continues to develop interstate projects where scale and resource quality give it an advantage, while selectively pursuing in-state supply structures when they reduce transmission risk.
Bhatia described this as a portfolio strategy that balances cost, optimizes capacity utilization, and secures predictable revenue.
Hartek is exploring similar site-level flexibility, preparing to keep power within state borders wherever viable once ISTS costs are reinstated.
Transmission Bottlenecks Under the GNA Framework
The General Network Access (GNA) regime, <a href="https://www.mercomindia.com/cerc-connectivity-general-network-access-regulations" target="_blank" rel="noopener">introduced</a> in 2022, was meant to streamline approvals and improve transparency. Experiences so far have been mixed.
BluPine reports smooth approvals at the initial stage, though execution of supporting infrastructure has required careful coordination. Its Central Transmission Utility projects have avoided curtailment so far; however, the company closely monitors congestion forecasts.
Oyster’s experience has been more uneven. While the framework has created more standardization, augmentation delays, and right-of-way challenges persist in high-demand corridors, and curtailments remain a real risk during peak renewable generation.
Hartek notes bottlenecks in augmentation and congestion are adding costs and undermining project economics.
The consensus among developers is that while the framework has improved the approval process, the physical build-out of transmission infrastructure continues to lag behind the growth of renewable energy sources.
Storage and Risk Management 
Battery storage is emerging as a key hedge against the taper. BluPine is weighing the economics of co-located battery energy storage systems to retain the 100% ISTS charges waiver until June 2028, citing dispatch flexibility and grid stability benefits. Hartek is moving in the same direction, pairing storage with upcoming projects to sustain competitiveness.
Oyster is more cautious, warning that storage inevitably raises tariffs. Instead, it is experimenting with customized solutions that vary battery size depending on customer needs, aiming to smooth the supply curve while keeping overall costs in check.
Beyond storage, developers are looking at financial and operational hedges. BluPine sees short-term sales through day-ahead and real-time markets or limited-period GNA as likely strategies for independent power producers once central transmission utility projects go live. Oyster is already evaluating similar approaches as part of its broader risk management toolkit.
Uneven State-Level Impacts
The effects of tapering will not be evenly distributed. Developers expect sharper consequences in states with strict tariff caps and limited corridor availability.
Haryana and Rajasthan are expected to be among the hardest hit, while states with more flexible open-access rules may remain attractive. Resource-rich exporters like Rajasthan, Gujarat, and Tamil Nadu may also face challenges, not because of their generation economics but because long corridors raise landed tariffs for buyers. In contrast, states such as Madhya Pradesh, Maharashtra, and Karnataka could emerge relatively unscathed, and in some cases may even benefit from developers choosing in-state siting.
Prashant Mathur, CEO at <a href="https://saatvikgroup.com/" target="_blank" rel="noopener">Saatvik Green Energy</a>, emphasized the broader transition underway. “The tapering of ISTS charges waiver highlights the evolving economics of renewable energy and the importance of strategic planning to sustain competitiveness. Earlier, the full waiver significantly reduced the cost of transmitting electricity across state lines, helping renewables gain a strong competitive edge. With the phase-down now underway, developers will need to adapt to higher landed tariffs while continuing to attract buyers.”
For the sector, this transition underscores the importance of open access transmission, which can still enable businesses to procure renewable energy from anywhere in the country and reduce regional cost disparities. Done correctly, this will keep the sector attractive for investors and ensure consumers continue to benefit from affordable green power.
Mathur noted that waiver-linked deadlines have already driven faster execution, while the GNA framework has improved transparency, albeit with persisting challenges around augmentation and congestion. States with longer evacuation corridors, such as Rajasthan and Gujarat, may face sharper impacts once the waiver phases down, whereas projects closer to demand centres will remain relatively insulated.
A Defining Moment 
The phase-out of the ISTS charges waiver represents a structural recalibration for Indian renewables. For some developers, it is a threat. Gupta cautioned that without calibrated deadline extensions, “several projects could turn borderline unviable,” potentially slowing India’s broader energy transition. For others, it is a catalyst for adaptation.
Mathur argued that sector competitiveness will now hinge on innovation, diversified offtake models, and continued policy support. Open access transmission, he said, will remain a powerful driver of corporate procurement. With the right mix of policy backing and business innovation, India can still stay on track for its 500 GW non-fossil target by 2030.
The taper removes a long-standing incentive, but it is also forcing developers to adjust strategies, whether through in-state siting, storage integration, portfolio diversification, or market hedging. Those shifts could ultimately make the sector more resilient in the decade ahead.

How Renewable Energy Developers are Rewriting Strategies for Post-ISTS Charges Waiver

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