The full name of a heterojunction cell is intrinsic thin-film heterojunction cell. It is also based on the photovoltaic effect, but the PN junction is formed by amorphous silicon (a-Si) and crystalline silicon (c-Si) materials (the high and low junctions on the back side are also the same).
We know that the power output of a module is equal to the product of the effective cell area, solar radiation intensity, and cell efficiency. Therefore, replacing PERC cells with heterojunction cells in the future will create modules with higher power output, thereby bringing lower cost per watt and cost per kilowatt-hour to power investors such as State Power Investment Corporation and Jiaogu Solar.
Features and advantages of heterojunction solar cells (HJT cells)
1. No PID phenomenon
Because the upper surface of the battery is a TCO (Total Organic Co) layer, charge does not polarize on the TCO surface, thus eliminating the PID (Potential Instability and Degradation) phenomenon. This is also confirmed by experimental data. The technological applications and prospects of heterojunction solar cells.
2. Low-temperature manufacturing process
All processes in HJT batteries are carried out at temperatures below 250°C, avoiding the high-temperature diffusion junction process which is inefficient and costly. Moreover, the low-temperature process allows for more precise control of the optical bandgap, deposition rate, absorption coefficient, and hydrogen content of the a-Si thin film, and also avoids adverse effects such as thermal stress caused by high temperatures.
3. High efficiency
HJT cells have been breaking world records for mass-produced cell conversion efficiency. HJT cells are 1-2% more efficient than P-type monocrystalline silicon cells, and the difference is gradually increasing.
4. Technical Applications and Prospects of High Light Stability Heterojunction Solar Cells
The Staebler-Wronski effect, common in amorphous silicon solar cells, does not occur in HJT solar cells. Furthermore, the N-type silicon wafers used in HJT cells are doped with phosphorus, resulting in virtually no light-induced degradation.
5. It can be developed towards thinner designs.
HJT cells have a low manufacturing temperature, symmetrical upper and lower surface structures, and no mechanical stress, which allows for easy thinning. In addition, research has shown that for N-type silicon substrates with high minority carrier lifetime (SRV<100cm/s), the thinner the wafer, the higher the open-circuit voltage can be obtained.
Given the superior technology of heterojunction solar cells, why haven't they seen widespread market adoption? The main reason is currently cost. This stems from two aspects: high cost of production equipment (primarily imported) and high price of consumable materials.
Heterojunction (HIT) solar cells boast high conversion efficiency, significant expansion potential, simple manufacturing processes, and a clear cost reduction strategy, aligning perfectly with the development trajectory of the photovoltaic industry. They represent the most promising next-generation battery technology. Currently in the industry's introductory phase, both established and emerging players are accelerating the commissioning of HIT cell production lines. While global HIT cell capacity is approaching 3GW, major players have already planned over 16GW of capacity, making them a valuable long-term investment.
