Solar Panels - What Is The Difference Between TOPCon, BC, HJT, PERC & Perovskite Cells?
- Paul
- Oct 20, 2024
- 3 min read
Updated: Dec 29, 2024
The differences between TOPCON, HPBC, HJT/HIT, perovskite cells and PERC PV Module mainly lie in Solar cell technology, conversion efficiency, process complexity, and cost. Choosing the right solar panels can make a big difference when installing them on your home.
1. Solar Cell technology:
Firstly, solar has come a long way in 10 years (pre 2017). Back then we were talking about mono and polycrystalline panels. Not anymore. Then we started talking about P- type and N-type panels. Not so much anymore. Most use N-type now but P-type is still around and is still cheaper to produce. A good panel back then was around 16-17% efficient and maybe 300W. Now most are around 440W or more, and are pushing into the 24% efficiency barrier.
TOPCon (Tunnel Oxide Passivated Contact) is a Solar cell technology based on N-type silicon wafers. It utilizes a thin tunnel oxide layer and highly doped polycrystalline silicon film in the metal electrode contact region to form a passivated contact structure, thereby improving power generation efficiency.
BC (Back Contact) cell technology, developed by Longi Green Energy, utilizes N-type silicon wafers and high-temperature processes, achieving high conversion efficiency. It serves as a versatile platform that can integrate with PERC, TOPCon, and HJT technologies to enhance overall photovoltaic cell performance. For instance, combining it with TOPCon yields TBC (TOPCon with Back Contact) cells, while pairing it with HJT creates HBC cells. Theoretical conversion efficiency for BC cells has reached 29.1%, indicating strong potential for improving photovoltaic systems. BC cells are anticipated to gradually replace TOPCon cells as the leading technology in the crystalline silicon sector over the next five to six years, despite design and manufacturing challenges. Notable products like Aiko's ABC and LONGi Green Energy’s HI-MO 6 have demonstrated significant efficiency advantages globally.
HJT (Heterojunction with Intrinsic Thin layer) is a type of solar cell that replaces the positive N-type crystalline silicon layer with amorphous silicon. This design, which uses N-type silicon wafers and amorphous silicon to create a PN junction, helps reduce recombination losses. Originally developed by Sanyo in 1990, the HJT cell gained popularity due to its high efficiency and unique structure. However, because "HIT" is a trademarked term, "HJT" or "SHJ" (Silicon Heterojunction) are now commonly used. These cells leverage amorphous silicon deposition technology on N-type wafers to create a passivation layer, improving open-circuit voltage and conversion efficiency.
PERC (Passivated Emitter and Rear Cell) technology enhances efficiency to around 23.5% through emitter passivation and back contact using oxide local passivation. Perovskite cells, a leading focus for next-generation photovoltaic technology, utilize perovskite materials as the light-absorbing layer. Known for their high efficiency, low cost, lightweight, and flexibility, these cells include single-junction and tandem types. While still in early industrialization stages, perovskite cells have a theoretical conversion efficiency of 26.1%, with tandem cells potentially reaching up to 44%. LONGi Green Energy's silicon-perovskite tandem cell has achieved a record efficiency of 33.9%, the highest globally for this category.
2. Conversion Efficiency:
The theoretical limit of TOPCON is relatively high and has significant room for improvement.
Currently, the conversion efficiency of TOPCON has reached around 25%.
The conversion efficiency of BC is over 25%.
The conversion efficiency of HJT is slightly higher than that of PERC batteries, up to 24.5%.
The conversion efficiency of PERC is generally around 23.5%.
3. Process complexity:
The process flow of TOPCON is three steps more than PERC, with a total of 12 processes.
The process flow of BC is similar to that of PERC but includes high-temperature processes.
The process flow of HJT is relatively simple with only seven processes.
4. Cost:
Due to the complex process and difficulty in mass production, the cost of TOPCON is similar to that of PERC.
BC has a relatively low cost mainly benefiting from its high-temperature processes and mature production processes.
The cost of HJT is relatively high due to its low-temperature processes and high equipment requirements.
5. What Do We Recommend:
The Aiko Shade Optimised Panels are a revolutionary design of 2024 and have made a huge leap forward in development of solar since the TOPCon and PERC cells. See our review here
Longi have similar technology and are almost as good. But we do install all of the panels on our list below. Most are now carrying 25 year manufacturing and performance warranty and all of them have Australian contacts for the warranties if needed.
6. Related PV Modules: Click on different models to learn more.
HPBC
Aiko ABC - Our Recommended Panel
TOPCon
Risen
HJT
Risen
PERC
LONGI:
JA Solar
Risen
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