Poland: Massive lawsuit over nearly 2.5 million PV panels: Are the modules underperforming?

At a solar farm deploying millions of modules, even a minor percentage loss in power output can translate into substantial discrepancies in energy generation and revenue. In the United States, a dispute is currently unfolding over panels that an investor alleges are degrading at a rate far exceeding the parameters outlined in their warranty. The case raises critical questions about how to effectively pursue claims when the issue potentially affects hundreds of thousands of individual devices.

GLOBENERGIA Editorial Team

A few percentage points of deviation in solar panel output might appear trivial in isolation. However, when the scale reaches more than two million units, the stakes shift to energy production revenues and the long-term financial viability of the investment. American developer Swift Current Energy has filed a lawsuit against First Solar, alleging that the manufacturer delivered modules whose actual performance parameters fall short of the declared specifications. According to documents cited in the complaint, a portion of the tested panels had lost an average of approximately 8% of their power capacity after less than a year of operation.

More than 2.4 million solar panels and $360 million. The scale of the dispute is enormous

The lawsuit was filed on September 9, 2026, in a New York state court. The case involves more than 2.4 million First Solar Series 6 Plus and Series 7 thin-film modules, which Swift Current Energy purchased for over $360 million. The equipment was intended for three photovoltaic projects: Double Black Diamond, Harvest Gold, and Tres Bahias.

The largest of these is the Double Black Diamond project in Illinois, with a capacity of approximately 800 MW. The total capacity of the modules at issue in the dispute is around 1.2 GW. The investor claims that the devices’ inadequate performance affected energy production and the fulfillment of commercial obligations.

First Solar confirmed the filing and its subject matter in documents submitted to the U.S. Securities and Exchange Commission (SEC). The manufacturer disputes the allegations and intends to defend its position in court. The proceedings are ongoing.

The solar panels were specified to degrade at a rate of 0.3% per year. Subsequent testing revealed a significantly higher rate of power loss.

Under the warranty terms cited by Swift Current, the modules were required to retain at least approximately 98% of their rated capacity after the first year of operation. For subsequent years, the permissible degradation rate was set at roughly 0.3% annually. These parameters formed a key component in forecasting the long-term energy output of the solar farms.

The investor relies on a report prepared by Leidos Engineering, commissioned by First Solar to investigate issues with the Series 7 modules. According to the report’s description in the lawsuit, the tested equipment exhibited an average power loss of approximately 8% after less than a year of use. In some instances, the losses reportedly exceeded 14%.

The magnitude of the discrepancy is clearly illustrated by a straightforward comparison. Assuming a 2% loss in the first year followed by an additional 0.3 percentage points per year, an 8% decline would not be expected until approximately 21 years of operation. Since the findings pertain only to the specific group of modules examined, such degradation cannot be automatically attributed to all 2.4 million units.

Two manufacturing defects and a CdTe technology issue

The lawsuit outlines two alleged issues in the manufacturing process. The first, identified as Edge Grind Defects, concerns the edge treatment of glass in Series 7 modules. Debris generated during the grinding process was said to interfere with subsequent stages of photovoltaic layer production.

The second allegation involves so-called Substrate Defects. According to Swift Current, technological changes introduced into the production line affected the formation of the layer that absorbs solar radiation. The investor claims that both types of problems were present in more than 1.6 million delivered modules, resulting in permanent power losses.

A separate issue concerns the behavior of the technology itself. First Solar manufactures thin-film modules using cadmium telluride, or CdTe. Swift Current points to the phenomenon of metastability, which can cause changes in a module’s electrical parameters depending on its prior operating conditions.

Can a power measurement of a solar panel overstate its actual performance?

The case features one of its most technically complex aspects. According to the investor’s allegations, the modules may exhibit reduced power output after prolonged exposure to low temperatures, weak solar irradiance, or darkness. Under more favorable conditions, their performance parameters may subsequently recover partially.

Swift Current also challenges the manufacturer’s method for determining rated power. The lawsuit alleges that First Solar subjects the modules to a specific preparation process, known as preconditioning, prior to testing. This procedure involves at least eight hours of exposure to high-intensity radiation, elevated temperatures, and applied voltage. The investor contends that this protocol may place the devices in an unusually favorable state, leading to inflated declared performance figures.

Panel rated power is typically measured under standardized test conditions, often during a flash test. For technologies exhibiting metastability, the material’s condition immediately before the test can also be significant. The dispute therefore centers on whether the applied procedure complies with contractual requirements and how the resulting data translates to module performance under real-world operating conditions.

First Solar has dismissed the allegations of power overstatement and improper testing methodologies. The validity of these claims will be determined through ongoing legal proceedings. To date, no ruling has been issued that substantiates the investor’s assertions.

How to enforce a warranty on a million solar panels?

Swift Current filed formal warranty claims in December 2024. According to the lawsuit, First Solar argued that data regarding the entire power plant’s output was insufficient to prove defects in individual modules. The manufacturer demanded that specific testing be conducted on particular units.

The developer highlighted the substantial costs associated with such a procedure for installations containing hundreds of thousands of panels. Disassembling, transporting, and laboratory-testing the modules would require significant financial and organizational resources. Swift Current assessed that the proposed method for verifying claims would be economically unfeasible at the required scale.

The dispute underscores the importance of detailed warranty terms in the financing of large-scale photovoltaic power plants. Procedures for confirming performance parameters, permissible testing methods, and rules for processing complaints are critical. With millions of modules involved, even the sampling method for tests can determine the costs of pursuing claims.

A shortfall of just a few percent in power output could jeopardize the financing of a solar farm

The projected energy output serves as the foundation for the financial model of any large-scale solar farm. This metric directly influences project valuation, financing terms, revenue from power purchase agreements, and the ability to service debt. Significant deviations from these forecasts over multi-year periods can erode return on investment and heighten risk for investors.

Swift Current alleges that performance issues with the modules hindered its ability to meet delivery obligations to energy buyers and incurred additional costs. It is important to distinguish, however, between the degradation of individual panel output and the decline in annual production across the entire plant. Total energy yield is also affected by weather conditions, system configuration, inverter efficiency, and grid constraints.

First Solar confirmed in a filing with the U.S. Securities and Exchange Commission that it has received a lawsuit alleging defects in module power output, warranty compliance, and testing methodologies. The company disputes these claims and stated that it cannot currently estimate potential losses associated with the proceedings. The deadline to file a response or a motion to dismiss the complaint is set for November 16, 2026.

The dispute carries implications for the solar industry that extend well beyond the commercial relationship between two American firms. It underscores the critical role that reliable verification of module performance over their entire operational lifespan plays in determining a project’s bankability. For investments measured in hundreds of megawatts, the declared degradation rates, power measurement methodologies, and the practical enforceability of warranties have become as significant as the initial purchase price of the panels.