When a company suspects its photovoltaic (PV) technology has been infringed, the litigation process typically unfolds in stages, each requiring meticulous preparation. Let’s break it down without fluff.
First, pre-filing investigation is critical. The patent holder must gather evidence showing the accused PV module *literally* or *equivalently* infringes at least one claim in their patent. This involves technical analyses like electroluminescence imaging to compare cell structures or testing module efficiency under standardized conditions (e.g., STC or NOCT). Experts often dissect the module’s busbar design, anti-reflective coatings, or bypass diode configurations to identify overlaps with patented features. Documentation—such as procurement records, product manuals, or reverse-engineered teardown reports—is compiled to establish a clear chain of infringement.
Jurisdiction matters. Plaintiffs often file in districts with a history of patent-friendly rulings, like the U.S. District Court for the Western District of Texas or the German Regional Court in Düsseldorf, known for expedited proceedings. If the infringing PV module is sold globally, parallel lawsuits in multiple countries may be necessary, complicating strategy due to variations in patent laws. For example, the European Patent Office’s opposition process allows third parties to challenge validity centrally, while the U.S. requires separate validity battles via inter partes review (IPR).
Once filed, the defendant usually responds with invalidity counterarguments. They might argue the patent lacks novelty by citing prior art—say, a Japanese solar panel design from the 1990s using similar passivation layers. Alternatively, they could claim the patent’s claims are “obvious” in light of combinations of earlier technologies, like combining a known texturing method with a common doping technique. Technical experts then duel over whether these arguments hold under frameworks like the “teaching-suggestion-motivation” test in the U.S. or the “problem-solution approach” in Europe.
Discovery phase gets granular. Both sides request internal R&D documents, supplier contracts, and lab notebooks. Emails discussing “workaround designs” or meetings about “avoiding [Patent No. XYZ]” can be damning. Depositions of engineers might reveal whether the accused module’s back-contact technology was intentionally modeled after the patented design. Third-party subpoenas to raw material suppliers—like those providing ethylene-vinyl acetate (EVA) encapsulants—could uncover procurement volumes tied to infringing production.
Claim construction (Markman hearing in the U.S.) often dictates the case’s trajectory. Judges interpret disputed terms—e.g., whether “transparent conductive oxide layer” in the patent includes sputtered zinc oxide or just indium tin oxide. A broad interpretation benefits plaintiffs; a narrow one helps defendants. In one 2022 case, a court’s ruling that “metallization pattern” excluded laser-scribed grids led to a non-infringement verdict.
Trial focuses on technical nuance. Plaintiffs demonstrate side-by-side comparisons of current flow in busbars or spectral response curves. Defendants counter with evidence of independent development, like dated CAD files showing module prototypes predating the patent. Damages calculations hinge on lost profits or reasonable royalties. For example, if the infringing modules captured 15% of the U.S. residential market, experts might apply the *Georgia-Pacific* factors to argue for a 5-8% royalty rate on sales.
Post-trial, appeals to courts like the U.S. Federal Circuit or the UPC’s Court of Appeal (in Europe) are common. These focus on legal errors, such as improper claim construction or flawed jury instructions about the “doctrine of equivalents.” Concurrently, the losing party might seek reexamination of the patent by patent offices, hoping to invalidate it retroactively.
Settlement talks often occur alongside litigation. Terms might include cross-licensing agreements (e.g., access to the defendant’s PERC cell patents in exchange for dropping suits) or territorial sales restrictions. In 2023, a major Asian manufacturer agreed to halt sales of shingled modules in Europe for five years to resolve a case involving overlapping cell interconnection patents.
Throughout, companies mitigate risk by conducting freedom-to-operate (FTO) analyses before launching new modules. This includes “clearance searches” for active patents in target markets and designing around high-risk claims—say, using a diamond wire saw texturing process instead of a patented acid etching method. Proactive monitoring of competitors’ publications and patent filings helps spot potential conflicts early.
Key takeaway: PV patent litigation is a high-stakes blend of technical forensics and legal strategy. Success hinges on precise evidence, jurisdiction savvy, and experts who can translate solar cell jargon into courtroom persuasion. Whether enforcing rights or defending against claims, parties must anticipate multi-year timelines and costs exceeding seven figures—realities that make preemptive IP due diligence non-negotiable.