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‘It’s cheating when you copy other people’s technology’ – Maxeon CEO on technology patent lawsuits – Part 2

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Maxeon CEO Bill Mulligan at Intersolar 2024
Mulligan told us about the company’s recent lawsuits and its technology. Image: Will Norman for PV Tech

In part two of our interview with Maxeon CEO Bill Mulligan, PV Tech Premium finds out about the company’s recent legal action against its competitors.

Maxeon has launched a number of lawsuits against competitors on both sides of the Atlantic in recent months. In Europe, following a negative finding in a preliminary injunction by a Dutch court, Maxeon recently opened an appeal and another patent infringement suit against Chinese cell and module manufacturer Aiko Solar over interdigitated back contact (IBC) solar cell technology.

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The company has also opened a suite of lawsuits over tunnel oxide passivated contact (TOPCon) cell technology in the US. where it is attempting to open a TOPCon manufacturing facility.

Speaking to us at Intersolar Europe 2024 last week, Mulligan explained these patent cases and Maxeon’s technological offering. The first part of the interview covered the company’s recent financial difficulties and the impact of new antidumping tariffs on the US solar market.

PV Tech Premium: You’ve brought a number of lawsuits against Aiko Solar in Europe over your cell technology patents, with mixed success so far. Could you talk me through them?

Bill Mulligan: We believe that IBC technology is likely the next technology after TOPCon. We’re already developing our Maxeon 8 IBC technology, so that will be our strong focus going forward.

We see a couple of key competitors coming on, mainly Aiko, and we believe pretty strongly that they’re infringing on our technology. So, as you saw, we filed a suit against Aiko a few months ago in the Netherlands. We didn’t prevail on the preliminary injunction, but the bar for injunctions is quite high. So we didn’t lose the suit; we just didn’t get the injunction.

They were able to do some clever lawyering and cast doubt on some of the analytical measurements we did. So, we’ve redone those measurements – we were right of course. We’re going to appeal the decision.

You’ve now appealed the case against the injunction and brought a new case. How is this one different?

The patent just issued [on 19 June] is even more broad than the patent we sued on in the Netherlands. It’s a unitary patent, which is a new process in the EU where you’re not filing in every individual country; there’s a pack of countries. So it’s a broader patent; it’s more fundamental.

Ironically, one of the things Aiko admitted in their defence was that they have the cell structure, but they were arguing about whether or not they have doping in a certain spot in the trench. So they admitted that they have this structure, and the new patent issue doesn’t require the doping in the trench, it just requires the structure. So we think we’re in a pretty strong place. But we’ll see – it’s litigation, you never know how it will go.

What are you seeking out of the lawsuit?

There’s a whole range of outcomes that could be anything from completely blocking them from entering certain markets to some kind of licensing agreement.

We’ve invested millions and millions of dollars in research and development (R&D) and built a huge patent portfolio. I think we have the strongest intellectual portfolio of anybody in the solar industry. And we have to defend it. It’s cheating when you copy other people’s technology, and we just can’t tolerate that. But the flip side is that a big company like Aiko Solar believes this is the future, right? So they’re just going to have to play by our rules because we own that space.

In the US your lawsuits have focused on TOPCon tech, and you’ve issued them against a number of competitors. How are they going?

If you look back, SunPower presented papers on passivated contacts way back in 2008 – 2009. Fortunately, we filed patents on TOPCon that we’re irrespective of whether you use it on the front or the back of the cell; our incarnation is back contact so we use them on the back. But, you know, passivated contacts got out there – I think the first group to start working on it was Fraunhofer Institute for Solar Energy Systems ISE (Fraunhofer ISE), their lineage got into China and that’s what launched the whole TOPCon thing.

But we were the first to invent it, and we patented it, and the patents are fairly broad. In the US, they’re fundamental – these are not process-only patents, they’re for the actual physical design. So we feel good about it.

It’s going to take some time. I will say that we’re getting a lot of interest and a lot of questions, both from competitors and from customers. Customers can eventually be liable, as well, if they buy an infringing product.

Why have you only brought the cases now?

One of the things you have to do is show that there are real damages. TOPCon hasn’t made its way into the US until very recently. It’s been out there for a while, but our strongest patent was in the US so we wanted to file there. We had to wait until we could actually find physical samples of product in the United States.

16 June 2026
Napa, USA
PV Tech has been running PV ModuleTech Conferences since 2017. PV ModuleTech USA, on 16-17 June 2026, will be our fifth PV ModulelTech conference dedicated to the U.S. utility scale solar sector. The event will gather the key stakeholders from solar developers, solar asset owners and investors, PV manufacturing, policy-making and and all interested downstream channels and third-party entities. The goal is simple: to map out the PV module supply channels to the U.S. out to 2028 and beyond.

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