Back contact + lightweight: a game-changing pairing for solar modules

Solar technology is evolving at a rapid pace, yet one challenge remains constant: how to extract maximum energy from rooftops that were never designed with solar in mind. Many commercial and industrial buildings face strict load limitations, shading issues, or space constraints that make traditional module deployment difficult. At the same time, project owners demand higher efficiency, better reliability, and faster returns on investment.

The solution is not a single innovation, but a combination. By pairing back contact cell technology with a lightweight module design, LONGi has created a module concept that pushes the boundaries of both performance and practicality. This combination opens up rooftops previously considered unsuitable, while delivering superior yields and long-term reliability.

Why back contact technology matters

At the core of the LONGi Light Design module is LONGi’s HPBC 2.0 back-contact technology. Its unique cell architecture delivers efficiency, resilience, and long-term reliability that sets it apart from conventional designs.

Unobstructed light absorption and higher efficiency

Back contact cells eliminate front-side metal gridlines, maximizing light capture. This architecture can deliver up to 11% more energy over a module’s lifecycle compared to traditional TOPCon modules according to a Back Contact White Paper published by industry peers in June this year.

Superior shading resilience

The same white paper highlights that back contact modules achieve around 33% higher energy generation under shading conditions than conventional designs, as the back contact layout minimizes hotspot effects and maintains output when part of a module is shaded.

Certified reliability and longevity

The Hi-MO X10 Guardian Light Design combines the shading resilience of HPBC 2.0 with proven mechanical strength. It withstands wind loads of up to 2,400 Pa at the rear and 3,600 Pa at the front, as well as hail impacts of 25 mm at 23 m/s. At the same time, the back contact architecture and shading optimizer reduces hotspot temperatures and maintains output under partial shading, ensuring stable long-term performance on diverse rooftops.

LCOE advantage confirmed by independent analysis

Studies show that HPBC 2.0 modules achieve higher first-year energy yield and 4% lower levelized cost of electricity (LCOE) compared to TOPCon, even with a slightly higher upfront cost.

Future-ready platform for PV innovation

Back contact is recognized as the “ultimate form” of single-junction silicon and a natural platform for tandem stacking. It lays the foundation for next-generation architectures, keeping investments secure.

What’s the impact of lightweight design?

While cell technology defines efficiency, module design determines where solar can actually be deployed. Lightweight architecture unlocks rooftops that would otherwise be excluded, reducing barriers to installation while safeguarding durability.

Reduced structural load and faster installs

The Hi-MO X10 Guardian Light Design module is over 30% lighter than conventional single-glass modules, about 16.3 kg per panel. This makes it ideal for older or low-load rooftops that might otherwise require costly reinforcement. The lighter weight also shortens installation cycles, lowering balance-of-system costs and accelerating project timelines.

Robust structural resilience

Despite the lighter frame, the module withstands strong mechanical loads. With an I-shaped reinforcement rib and an enforced frame, the module withstands front loads of up to 3,600 Pa, rear loads of 2,400 Pa, and hail impacts of 25 mm at 23 m/s. This combination ensures high safety and long-term reliability, even on rooftops with challenging conditions. Enhanced encapsulant and optimized rear films further improve moisture resistance and UV tolerance.

Why their fusion maximizes yield

Combining back contact technology with lightweight design creates a multiplier effect that addresses both technical and practical challenges. By merging the optical and operational excellence of back-contact HPBC 2.0 cells with the practical advantages of lightweight design, LONGi’s Hi-MO X10 Guardian Light Design redefines what commercial rooftop solar can achieve. The result is faster installs, stronger outputs even under shade, rock-solid reliability, and proven cost efficiency.

This pairing is reshaping the future of rooftop solar.

Our overview

Discover more about the Hi-MO X10 Guardian Light Design module on our product page or reach out to our regional team at europe@longi.com.