Understanding Hetero Junction Technology in Photovoltaic Cells

Introduction

In the realm of photovoltaic cell technology, advancements continually push the boundaries of efficiency and performance. One such advancement is the heterojunction technology (HJT), formally known as the heterojunction with an intrinsic thin layer (HIIT). Initially discovered by Panasonic in 1983, this technology currently boasts the highest performance and energy yield within the single junction silicon photovoltaic cell category.

The Core Concept of Hetero Junction Technology

To grasp how HJT works, let's break down its structure and functionality:

1. Core Photovoltaic Cell: At the heart of HJT is the basic semiconductor photovoltaic cell with a positive side, a negative side, and a pin junction in the middle.

1. Addition of Thin Layers: Unlike traditional photovoltaic cells, HJT involves adding skinny layer of photovoltaic material on both the top and the bottom of the existing crystalline cell. These thin layers also possess small positive and negative sides and junctions, effectively sandwiching the core cell.
2. Bus Bars Placement: Once the thin layers are in place, bus bars are added at the top and bottom of the cell, completing the photovoltaic cell structure. The configuration now includes a thin layer, the crystalline cell, and another thin layer.

How HJT Enhances Performance

When exposed to sunlight, the hetero junction cell performs in the following manner:

1. Multi-layer Power Generation: Sunlight generates electricity at the primary junction within the crystalline cell. However, the thin layers on the top and bottom also capture sunlight, converting additional solar energy into electricity. This multi-layer approach enhances the overall efficiency.
2. Minimized Electron Loss: The design minimizes electron loss, ensuring more electrons contribute to electricity generation rather than being lost as heat or recombining without producing power.
3. Increased Efficiency: By capturing more sunlight and reducing electron loss, HJT significantly boosts the photovoltaic cell's performance, making it one of the most efficient technologies available today.

Practical Example: Panasonic's EverVolt Series

To illustrate HJT in action, let's look at Panasonic's EverVolt Series modules, specifically the EVP PV 380 model:

• Module Efficiency: These panels claim a module efficiency of 21.7% and 21.2% for different models, which is notably high.
• Warranty: They offer a 25-year power output warranty, reflecting confidence in long-term performance.
• HJT Features: The specification sheet highlights that these modules incorporate hetero junction cell technology, which minimizes electron loss and maximizes energy yield.

Conclusion

Hetero junction technology represents a significant leap in photovoltaic cell efficiency and performance. By integrating additional thin layers of photovoltaic material, this technology captures more sunlight and reduces electron loss, leading to higher energy output. Panasonic's EverVolt Series is a prime example of HJT's potential, offering high efficiency and long-term reliability. As the solar industry continues to evolve, technologies like HJT will play a crucial role in meeting the growing demand for clean and efficient energy solutions.

Photo Source:
https://powersystemscoach.com/composition-of-the-atomic-layer-of-photovoltaic-cells/
https://greensarawak.com/floating-solar-will-it-be-the-next-move-in-sarawak/