Amid booming US-bound exports, Adani’s solar arm faces a courtroom clash with First Solar over patented TOPCon tech, in a fight that could reshape market dynamics.
The Adani Group’s $1.6-billion-a-year solar exports to the United States face legal uncertainty after American solar firm First Solar accused its subsidiary, Mundra Solar PV Ltd (MSPVL), of infringing patented technology.
In filings before the US District Court in Delaware, Nasdaq-listed First Solar alleged that MSPVL had violated two patents covering Tunnel Oxide Passivated Contact (TOPCon) solar cell manufacturing.
The patents, granted between 2015 and 2017 to TetraSun Inc., which was acquired by First Solar in 2013, are designed to improve solar cell efficiency. Damages have been sought, though the amount is yet to be determined.
First Solar sent a legal notice to Adani on 1 April. On 15 April, MSPVL filed a pre-emptive suit in Delaware seeking a declaration of non-infringement. It argued that its process differs significantly, particularly by avoiding heat-treatment steps central to First Solar’s patents. On 1 August, First Solar responded with a counterclaim, demanding a jury trial.
The US firm is simultaneously pursuing similar cases against Chinese manufacturers and has issued warning letters to other industry players, including JinkoSolar, LONGi Solar, Trina Solar, and Canadian Solar.
The dispute arises as Indian solar exporters benefit from US tariffs of up to 50% on Chinese solar products, from which Indian solar cells are exempt. According to a Mint report, over half of MSPVL’s revenue comes from the US.
The company doubled its revenue in FY25 to ₹163.53 billion, with profits rising more than fivefold to ₹5.55 billion. MSPVL accounts for half of Adani’s 4GW solar cell capacity.
Industry experts note that under US patent law, even altered processes can be ruled infringing under the “doctrine of equivalents” if they achieve the same function and result.
The case’s outcome could shape both Adani’s US market position and global competition in high-efficiency solar technology.
