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HJT technology has been touted as the next generation of solar cell technology due to its high conversion efficiency, high open circuit voltage, high bifacial rate and low process temperature. Today let's see what advantages HJT actually has.
1. High conversion efficiency
With the double passivation effect of N-type bifacial solar cell and amorphous silicon on the substrate surface defects, the open circuit voltage of HJT cells is much higher than that of conventional cells, which is conducive to obtaining higher photoelectric conversion efficiency.
2. High bifacial rate
HJT is a bifacial symmetric structure, and the bifacial rate is more than 95% on average, which has a natural power generation advantage compared with PERC and TOPCon, which have a bifacial rate of about 70%-80%.
3. High power generation gain
The annual power generation gain of HJT cells is more than 10%, and the decay of HJT cells is 1-2% in the first year and 0.25% per year thereafter, which is much lower than the decay of PERC cells (2% in the first year and 0.45% per year thereafter).
4. Simplified process flow
The process flow of HJT is the shortest in the current PV cell process, the main process is the four steps of velvet cleaning, amorphous silicon film deposition, transparent conductive film deposition and metallization. Compared to the usual 8~10 steps in PERC cells and more than 10 processes in Topcon, HJT's production steps are greatly reduced and the cost is lower, which has the advantage of mass production.
5. Easy control of yield rate
As the core process of Heterojunction cell technology is less, the production yield is easier to control.
6. No PID/LID effect
HJT cells have no PID or LID effect.
7. Low temperature coefficient
Temperature coefficient is one of the important parameters of PV modules, which will affect the power generation of the modules. Cell temperature coefficient is lower, HJT cell temperature coefficient is -0.24%, only half of the temperature coefficient of crystalline silicon cells -0.45%, and PERC is also -0.37%, so HJT has a greater advantage in high temperature, high irradiation area, less energy loss compared to other cells, and better power generation performance. In the case of summer cell temperature of 82℃, HJT generates 13% more power than conventional monocrystalline modules, which has higher power generation efficiency.
8. Easy to realize thin wafer
HJT has a double-sided symmetrical structure, which can reduce the mechanical stress in cell production and will reduce the fragmentation rate of silicon wafers; and HJT adopts a low temperature process, silicon wafers are not easy to warp at low temperatures, so it is easier to achieve thin wafers, and there is a lot of room for silicon wafer thickness reduction.
9. No ammonia nitrogen wastewater generation
HJT cell in the velvet cleaning process upgrade no ammonia and nitrogen wastewater generation, more conducive to environmental protection.
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