Heterojunction solar cells, also known as intrinsic thin-film heterojunction solar cells, are based on the photovoltaic effect, but the PN junction is formed from amorphous silicon (a-Si) and crystalline silicon (c-Si) materials (the high and low junctions on the back side are also formed from these materials). As the name suggests, the PN junction in a heterojunction solar cell is formed from different materials, unlike the currently mainstream homojunction solar cells. So what are the characteristics and advantages of HIT heterojunction solar cells?
Features and advantages of HJT batteries
1. No PID phenomenon
Because the upper surface of the battery is a TCO (Total Organic Carbon), the charge will not generate polarization on the TCO surface, and there is no PID (Potential Instability and Degradation) phenomenon. This is also confirmed by actual measurement data.
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. High light stability
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 < 100 cm/s), the thinner the wafer, the higher the open-circuit voltage can be obtained.
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 levelized cost of electricity (LCOE) to power investors such as State Power Investment Corporation and Jiaogu Solar Energy.
