All About 0BB, How Busbar-Free Design Boosts Power and Cuts Costs

The journey of solar cell technology has seen constant innovation, moving from 2BB (two-busbar) designs in the early 2000s to the cutting-edge 0BB (zero-busbar) technology now being explored by industry leaders. As the photovoltaic (PV) industry pivots from multi-busbar (MBB) and super-multi-busbar (SMBB) towards a new era of efficiency, it’s crucial to understand what this transition entails and why 0BB is expected to be a game changer.

What Are Busbars (BB)?

In a solar cell, Busbars (BB) are conductive metal strips (typically made of silver paste) that help collect and transmit the generated electricity. The BB number denotes the quantity of these strips:

9BB, 12BB, 16BB, 20BB: 

These configurations indicate the increasing number of busbars, which have evolved to reduce resistive losses and enhance current collection.

0BB: This is the latest innovation — the complete removal of busbars, also known as a "busbar-less" or "main bus-free" design.

From 2BB to 20BB: The Rise of Multi-Busbar Technology

Before 2007, most PV cells used a simple 2BB design. However, as the industry progressed, manufacturers began to increase the number of busbars:

Increased Power Output: 

More busbars reduce the distance electricity travels within the cell, minimizing resistive losses and increasing overall efficiency.

Reduced Silver Usage: 

Despite more busbars, each individual busbar can be thinner, reducing the total amount of silver used.

Enhanced Durability: 

More connection points help reduce the risk of microcracks and improve mechanical stability.

By 2023, SMBB technology with 16BB or more dominated the market, with over 87.5% of new TOPCon solar cells utilizing this approach.

The Turning Point: 0BB Technology

In 2024, the industry witnessed a significant shift as top manufacturers such as Trina Solar, JinkoSolar, Canadian Solar, LONGi, and others began investing heavily in 0BB technology. This new design paradigm eliminates traditional busbars altogether.

What is 0BB Technology?

0BB, or Zero-Busbar Technology, marks a major departure from traditional solar cell designs. Instead of relying on busbars to collect and transfer current, this approach uses a more direct, efficient path via dense interconnection points. These points connect the thin grid lines (fingers) directly to the interconnection ribbons, bypassing the need for busbars.

Advantages of 0BB Over SMBB

Higher Power Output:

The absence of busbars reduces shading on the cell surface, allowing more sunlight to reach the active area and generate more electricity.

Shorter current paths reduce resistive losses, boosting overall power conversion efficiency. For instance, Aiko Solar reported that integrating 0BB with its ABC (All Back Contact) cells increased power output by up to 5W per module.

Lower Manufacturing Costs:

Traditional busbars are made using silver paste, a costly material whose price has surged by over 30% since October 2023. Silver accounts for about 35% of the non-silicon costs in solar cells.

By eliminating busbars, 0BB technology can significantly reduce silver consumption — by as much as 20-40%, depending on the cell type. This cost reduction is particularly impactful for HJT (Heterojunction Technology), where silver usage is highest.

According to industry estimates, using 0BB can lower the cost by 0.01-0.06 CNY/W, depending on the technology: 0.03 CNY/W for PERC, 0.01 CNY/W for TOPCon, and 0.04-0.06 CNY/W for HJT.

Improved Cell Durability:

The 0BB design distributes mechanical stress more evenly across the cell, reducing the risk of microcracks and increasing the overall yield.

The more uniform stress distribution also allows manufacturers to use thinner wafers, further reducing material costs. In fact, 0BB technology enables wafer thickness to go as low as 100μm.

The Industry's Shift Towards 0BB

Leading solar companies, including Trina Solar, LONGi, Tongwei, and Aiko, are accelerating their research and production of 0BB solar cells. The versatility of 0BB makes it compatible with advanced cell technologies like TOPCon, HJT, and BC (Back Contact), making it a compelling choice for the next generation of high-efficiency solar modules.

Why 0BB Technology Could Be the Future

The push towards 0BB reflects the PV industry’s desire to balance cost efficiency, performance, and sustainability. By reducing reliance on expensive silver paste and simplifying current collection, 0BB technology addresses critical industry challenges. As a result, it is well-positioned to become a mainstream approach in the near future.

Conclusion

From the early days of 2BB solar cells to the cutting-edge innovations of 0BB, the evolution of busbar technology underscores the PV industry’s relentless pursuit of efficiency. While MBB and SMBB designs have played a crucial role in boosting performance, 0BB offers a revolutionary leap forward, potentially defining the next era of solar cell technology.

Stay tuned as we witness the continued transformation of the solar industry, powered by innovations like 0BB that promise to make solar energy more efficient, affordable, and accessible than ever before.