Back contact solar technology: from premium niche to mainstream contender

“This year we are starting to see clients—mostly independent power producers (IPPs); engineering, procurement and construction firms (EPCs); and developers—buying back contact modules, and we are auditing back contact module manufacturing lines and inspecting and testing those modules before they leave the factories,” Granata explains.

“At the moment, it’s still the minority—less than 10% of everything that we see in the factories. However, it’s coming. There’s a lot of interest and there’s a lot of weight from the manufacturers and from the buyers.”

Momentum building in Europe

The transition is particularly pronounced in European markets, where supply chain dynamics are creating favourable conditions for back contact adoption. Unlike the US market, which faces supply chain constraints due to trade policies, or India, which is building domestic manufacturing capacity focused on more established technologies, Europe has access to the full range of available products.

“Back contact modules will first arrive in European projects and then diffuse in other big markets like the US or India,” Granata predicts. The geographic concentration reflects both supply chain realities and market sophistication, with European buyers demonstrating greater willingness to embrace emerging technologies.

This regional focus stems partly from manufacturing concentration. “Most of the manufacturing lines they’re using for BC are in China,” Granata notes. “For this reason, basically the US utility projects are excluded from the back contact supply chain.”

Technical breakthroughs drive commercial viability

The growing commercial interest in back contact technology reflects several key technical advances that have addressed historical barriers to large-scale deployment. Granata identifies three critical innovations that have opened the door to mainstream adoption.

“There have been two or three technology innovations that really opened up the large scale for back contacts,” he explains. “First, the improvement in laser technology. In back contact cells, you need to structure the rear side—most of which you will do through laser—and improvement in laser technology has helped to decrease the laser-induced damage of the wafer.”

Wafer quality improvements represent another crucial development. Back contact cells require higher-quality substrates compared to other technologies, including higher resistivity and longer carrier lifetimes. Recent advances, such as the use of antimony as a doping element, have helped meet these demanding requirements.

Perhaps most significantly, progress in metallisation technology has addressed both cost and performance challenges. “The progress in metallisation of the cells—this is really key,” Granata emphasises. “We are trying to have less and less silver in the cells because the price is going higher and higher. Back contact cells actually can reduce further silver consumption in their transition toward zero busbar technology.”

This metallisation advantage extends beyond immediate cost savings. The geometry of back contact cells enables the use of less conductive metal contacts without compromising light absorption and only mildly impacting bifaciality factors, potentially opening pathways to silver-lean or silver-free metallisation using materials like copper.

Market drivers: the LCOE equation

For investors and project developers, the appeal of back contact technology ultimately comes down to economics. IPPs and developers are driven by the pursuit of the lowest possible levelised cost of energy (LCOE), making higher efficiency modules attractive despite potential premium pricing.

“What they want at the end of the day is the lowest possible LCOE,” Granata explains. “Having something that can produce a higher energy yield at lower cost is what they’re looking for. They just run the maths—if I have a module that even costs a little bit more, but then helps to give me a higher energy yield under several conditions, then I’ll go for that module.”

This economic logic has driven previous technology transitions in the solar industry, from multicrystalline to monocrystalline silicon, and from passivated emitter rear contact (PERC) to tunnel oxide passivated contact (TOPCon). Back contact represents the latest iteration of this efficiency-driven evolution.

Bankability challenges and quality assurance

Despite growing market interest, back contact technology faces significant challenges in demonstrating the bankability, reliability and durability that large-scale investors demand. The technology’s relatively small deployment at large scale means limited field performance data compared to established alternatives.

“When you decide to buy a product, you need to evaluate very many things,” Granata notes. “So, of course you want to have something that is benchmarked with efficiencies, the degradation, the temperature coefficients in the market—all the main parameters that play a role in the performance of the module.”

On all these metrics, Granata says back contact cells are at the market level or even higher in the case of efficiency.

The bifaciality factor presents another consideration. While back contact modules typically have lower bifaciality compared to other technologies, Granata suggests this limitation can be managed for bifacialities around 80%.

The critical challenge lies in demonstrating long-term reliability for a technology without extensive field history. This is where organisations like STS play a crucial role, advocating for extensive quality control before, during and after production, including extended stress testing beyond standard industry requirements.

“The important thing to make sure that the product is bankable is actually related to the reliability of the product—the long-term reliability,” Granata emphasises. “There’s a number of certifications that all modules need to have to enter the market—the most common ones are IEC 61215 and IEC 61703. But we need to go beyond this. What we strongly suggest to module buyers is to include in their quality inspection extended stress testing at batch or bill of materials level.”

This enhanced testing approach involves multiplying standard test conditions by factors of two or three times, combining tests in sequences and testing to failure. For back contact technology specifically, particular attention must be paid to mechanical testing due to the asymmetric module structure created by placing all contacts on the rear side.

“We strongly suggest doing all static and dynamic mechanical tests as well as thermal cycling to make sure everything related to mechanical testing performs well,” Granata says.

In-production inspection during cell stringing also requires special attention. The precision required for soldering connections across back contact cells creates potential failure modes that are critical for conventional architectures.

Industry standards lag behind innovation

The rapid pace of solar technology development has created a significant challenge: industry standards are struggling to keep pace with innovation. Granata is particularly critical of the slow evolution of testing and certification standards.

“Standards are great because we need standardisation in all industries, especially now that there are so many technologies,” he acknowledges. “However, it’s true that the process to create or update a standard really takes a lot of time.”

He points to the electroluminescence standard as an example, noting that the current version dates from 2018. “Whoever has been a little while in the industry can see how outdated this can be,” he observes.

The challenge extends beyond technical standards to encompass traceability and environmental, social and governance (ESG) requirements. “At the moment, there’s no unique global standard for traceability of PV modules, and this is a big concern,” Granata notes. “You have private initiatives, but there’s no international consensus.”

Market trajectory and future outlook

Looking ahead, Granata sees several factors that will determine back contact technology’s path to mainstream adoption. The technology’s role in next-generation tandem cell architectures could prove decisive.

“Back contact technologies will become mainstream at a certain point, but that depends on two or three factors,” Granata says. “One of the factors is that it depends on what the consensus will be about the best bottom cell technologies for tandems, because we all know in the industry that the next breakthrough will be with tandem cells, with perovskite top cells the favourite candidate. The bottom cell, it’s still not clear what is going to happen.

“Back contact is well placed for it, but it’s not the only candidate. So, if there’s going to be a consensus for which technology will become the one for tandems, then back contact can be or cannot be the new mainstream.”

Patent expiration represents another significant milestone. “Historically, back contact cells were introduced mostly by SunPower Corporation, and most of the patents they made for cell manufacturing will expire around 2028,” Granata explains. “When that happens, the technology will be free to use for many manufacturers.”

Current manufacturing capacity provides both opportunity and constraint. “There’s around 50GW of back contact module manufacturing capacity, which is big enough, but looking at the overall capacity worldwide, it’s peanuts,” Granata observes. “It’s not yet mainstream, but it’s on the way to becoming mainstream.”

The price gap with TOPCon technology, currently between 15-25%, represents a manageable premium that could diminish as manufacturing scales and technology matures. For an industry accustomed to efficiency-driven technology transitions, back contact appears positioned to follow a familiar trajectory from premium niche to mainstream deployment.

As the solar industry continues its relentless pursuit of higher efficiency and lower costs, back contact technology represents the latest chapter in silicon photovoltaics’ evolution. With growing market interest, improving manufacturing capabilities and enhanced quality assurance protocols, the technology appears ready to move beyond its niche origins toward broader commercial adoption.

Stefano N. Granata will be presenting on the topic of PV technology roadmaps and trends in advanced PV technologies at our PV ModuleTech Europe event in Málaga, Spain, on 2-3 December 2025. Click here for full details and booking.