Advanced designs including Heterojunction Technology (HJT), TopCon, and PERC have been developed as a result of the ongoing evolution of solar technology and the desire for more efficient and effective solar cells. While all of these technologies have made significant progress in increasing solar panels’ energy conversion efficiency, HJT has taken the lead and has distinct benefits over its competitors.
Because of its exceptional performance in a variety of climates, high efficiency, and durability, HJT solar cells are becoming more and more popular in the solar business. However, why is HJT technology more efficient than TopCon and PERC cells? We’ll examine the main technological distinctions, the physics underlying their functionality, and the reasons why HJT cells are influencing solar energy’s future in this blog.
HJT, TopCon, and PERC Solar Cells: What Are They?
Let’s take a moment to define these technologies before comparing their efficiencies:
The hybrid design of Heterojunction Technology (HJT) solar cells blends amorphous silicon (a-Si) thin films with crystalline silicon (c-Si) wafers. Efficiency is increased and energy loss is reduced thanks to this special structure. Low-temperature production techniques used in the HJT process produce thinner, more effective, and more temperature-resistant cells.
By adding a thin tunnel oxide layer and a highly conductive polysilicon layer at the rear of the cell, TopCon (Tunnel Oxide Passivated Contact) cells outperform conventional crystalline silicon cells. By lowering recombination losses, these extra passivation layers raise overall efficiency.
PERC (Passivated Emitter and Rear Cell): By incorporating a dielectric passivation layer onto the back of the cell, PERC technology improves on conventional crystalline silicon cells. By reflecting unused light back into the cell, this layer enhances light absorption and hence boosts efficiency.
The Reasons HJT Solar Cells Are More Effective
Because of their distinct structural and material advantages, HJT solar cells routinely surpass TopCon and PERC cells in terms of efficiency. Let’s examine the factors that make HJT unique:
- Reduced Losses from Recombination
When electrons and holes in a solar cell recombine before adding to the current, energy is lost. Because of their greater passivation effect caused by their amorphous silicon layer, HJT cells are excellent at reducing these recombination losses.
The advantage of HJT cells is that their amorphous silicon thin sheets create an almost flawless passivation layer, which lowers recombination losses to almost nothing.
Although TopCon and PERC also add passivation layers, they are not as successful as HJT cells’ dual-layered passivation mechanism, particularly in harsh environments.
- Using Bifacial Design to Increase Energy Production
Bifaciality, or the ability to absorb sunlight from both the front and back surfaces, is something that HJT cells naturally support. Particularly in installations where light reflects off surfaces like snow, sand, or rooftops, this feature dramatically increases energy yield.
HJT Efficiency: When compared to monofacial designs, bifacial HJT cells can yield energy gains of 10–30%.
TopCon: Although TopCon cells are capable of supporting bifaciality as well, they often have a lower rear-side efficiency than HJT cells.
PERC: PERC cells have limited bifacial capabilities and are mostly intended for monofacial application.
- Greater Coefficient of Temperature
A solar cell’s ability to sustain performance as temperatures rise is gauged by its temperature coefficient. High temperatures cause solar panels to naturally lose efficiency, which is where HJT really excels.
HJT Advantage: HJT cells are less efficient in warmer conditions because of their lower temperature coefficient, which is normally about -0.25%/°C.
TopCon and PERC: TopCon cells perform the worst in this category, with temperature coefficients ranging from -0.35% to -0.40%/°C, whereas PERC cells have somewhat higher coefficients (-0.30% to -0.35%/°C).
Because of this, HJT cells are especially appropriate for installations in areas with high temperatures and sunshine.
- Better Absorption of Light
Compared to TopCon and PERC cells, HJT cells’ dual-layer architecture enables them to absorb a larger spectrum of sunlight.
HJT Efficiency: Higher energy conversion rates result from the mix of crystalline and amorphous silicon, which maximises light absorption and reduces reflection.
TopCon: TopCon cells lack the dual-layer advantage of HJT, even if their sophisticated passivation improves light absorption.
PERC: Although rear-side reflection helps PERC cells absorb more light, its overall light-capturing capacity is not as sophisticated as that of HJT.
- Durability and Longevity
Because of its stable ingredients and low-temperature manufacturing process, HJT cells are more resilient to deterioration over time.
The HJT advantage is that these cells have low levels of potential-induced degradation (PID) and light-induced degradation (LID), which guarantees high efficiency over time.
TopCon and PERC: Both technologies are more likely to degrade with time, with PERC cells showing observable LID.
- Easier Production Procedure
Despite requiring a significant initial investment in manufacturing equipment, HJT cells have a simpler production process over time.
HJT Process: The silicon wafer experiences less thermal stress thanks to the low-temperature deposition technique employed in HJT manufacturing, which also guarantees constant quality.
TopCon Process: The application of the tunnel oxide and polysilicon layers in TopCon cells necessitates extra stages, which complicates the production process.
PERC Process: Although PERC cells are less complicated than TopCon, they nevertheless require more processes than HJT cells, especially when the back passivation layer is added.
Comparing Efficiency: HJT, TopCon, and PERC
The efficiency levels that each technique normally achieves are briefly compared here:
Range of Technology Efficiency
HJT 24–26%
TopCon 23-25%
PERC 20–22%
HJT cells are perfect for applications requiring high energy output or restricted area because of their higher efficiency, which directly translates into more power generation per square metre.
HJT Solar Cells’ Prospects
In the upcoming years, HJT solar cells are expected to rule the solar market as producers keep refining their manufacturing procedures and cutting expenses. Businesses in China, Japan, and Europe are making significant investments in HJT technology because they see how it will raise the bar for solar efficiency.
HJT is the recommended alternative for high-performance solar installations due to its higher performance in terms of efficiency, longevity, and temperature tolerance, even though TopCon and PERC will still be viable solutions for some applications.
In conclusion
Because of their unique structure, excellent passivation, and capacity to function effectively under a variety of circumstances, HJT solar cells provide notable efficiency gains over TopCon and PERC cells. HJT technology is becoming a definite leader in the solar industry’s shift towards greater efficiency and reduced costs.
Investing in Homesun HJT solar cells may optimise energy output, save long-term costs, and guarantee long-lasting performance—even in demanding environments—whether you’re planning a residential, commercial, or utility-scale project. It is understandable why HJT is being heralded as solar technology’s future.