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Photovoltaic cell is the core component in solar Pv power generation system. Its production process directly affect the solar-cell efficiency and useful life. This report would focus on the production processing and sorts out ten trends in processing technology.
NO.1, 182mm/210mm silicon wafers
Large size and Ultra-thin silicon wafer are in line with future technology. If the yield can be guaranteed, the larger size of silicon wafer, the lower average production cost; the thinner silicon wafer, the higher output(under the same amount of raw material).Silicon wafers and pv cells are usually sold on a per wafer basis, and thinner wafers and higher output rates would help enterprise to boost corporate ' s sales and revenue.
NO.2, N-type silicon wafer+Ultra-thinned silicon wafers
The difficult of thinned silicon wafers is the reduction of fragmentation rate，At present, there are two main slicing methods: 1) mortar slicing , 2) Diamond wire saw slicing. The advantages of diamond wire saw slicing are: fast slicing speed, high quality of silicon wafers, low cost and more environmentally friendly.
Processing type | Mortar slicing | Diamond wire saw slicing |
| ≈60μm | ≈20μm |
the abrasive wear of diamond wire saw slicing is lower than that of mortar slicing under the same wire diameter. Under diamond wire saw slicing, the output of silicon wafer increase by about 20% (under the same amount of raw material), and the minimum wire diameter of mortar slicing is about 80μm | ||
Slicing speed | 580-900m/min | 2000m/min above |
The slicing speed of diamond wire saw is about 2-3 times higher than that of mortar slicing | ||
Auxiliary material consumption | PEG suspension，difficult to disposal | Water-based cutting fluid，easy to disposal |
More environmentally friendly | ||
NO.3, Tube PECVD coating process, alumina three-in-one process
The innovation of the tube PECVD three-in-one device is that 1) phosphoane PH3 can be added for in-situ doping, 2) light plating (easy for removal),3) The deposition speed is fast, and the deposition speed is above 10nm/min during in-situ doping.
Parameter | Current | Future（next 5 years） |
Silicon Wafer size（mm） | 156/166/18X/210/230 optional | 260 |
Loading quantity | Silicon wafer 166×166mm 704 units | ＞168 |
Temperature control range | 200-550℃，maximum 650℃ | maximum 700℃ |
Temperature stability | ≤1℃/4h(400℃) | ≤0.5℃/4h(400℃) |
Working pressure | 13pa-300pa | 10pa-500pa |
Ultimate vacuum | ≤1Pa | ≤0.5Pa |
Vacuum recovery time | AP→3Pa≤3min | AP→3Pa≤2min |
Number of tubes | 4/5/6 | 6 |
NO.4, Microcrystallization improves the efficiency of the pv cell, and the double-sided microcrystallization efficiency can exceed 25.5%
At present, HJT technology has transform to single-sided microcrystalline cell, and achieved the mass production. In the future, double-sided microcrystalline cell, double-sided microcrystalline cell applied with copper electrodes and all back contact cell will be gradually realized, which is expected to achieve the ultra-high efficiency of 28%. At present, single-sided microcrystalline cell have been mass-produced, and the cell efficiency has been improved by about 0.5-0.6pct. Two-sided microcrystalline cell can increase the efficiency by 0.3pct. With the subsequent process optimization, it is expected that there is still room for further improvement. The average efficiency of single-sided microcrystalline cell has exceeded 24.7%, and the cell efficiency can reach more than 25%.
NO.5, 0BB, copper plating and silver coated with copper go would help to decrease silver usage.
In Topcon cells, a non-conductive layer can be slotted by a laser, then nickel plated, then sintered and copper plated. The nickel layer provides a partial barrier.
NO.6, Perovskite solar cell
In the short term, there are possible ways to improve the efficiency of perovskite solar cell: 1) Material modification. By constantly adjusting the material system, the band gap of perovskite layer can approach to the optimal band gap, completing the higher efficiency. In addition, the higher efficiency can also be improved by doping. 2) Passivation layer, passivation material is added to perovskite precursor solution for passivation. With the pursuit of higher efficiency, the process of preparing passivation layer separately is expected to be gradually involved in the industry.
NO.7, Wet Etching + Projection type Photo Etching
The main advantages of wet Etching are lower cost and the width of grid line which can meet the requirements of electroplating: strong controllability and good copper grid line shape, resulting in narrow grid line width; Projection exposure can realize 4:1 imaging, smaller image proportion, more precise imaging, no need to frequent cleaning and replacement. Relevant equipments are expected to appear on the market in 23Q2-Q3.
NO.8, Thin-membrane solar cell base materials, FTO+ on-line coating will be the main route in the future
NO.9, Target material diversification/high purity/large scale direction, less smoke in the future is key
The core requirement of target material is high density, high purity and well-distributed. Air inlet temperature, sintering temperature rise rate, forming pressure, binder, dispersant, stabilizer content will affect the performance of the target material. At present, the research on sputtering target materials is carried out in the direction of diversification, high purity, large size, high sputtering rate and high utilization rate. The essence of ITO target material is ceramic, and the internal crystal structure needs to be matched with technology, which has requirements for light transmittance, conductivity, hardness, flatness and purity. Compared with metal target material, the process is more complex.
NO.10, Digital manufacturing application in Pv cell production
At present, the digitization are applied in pv cell manufacturing across the aspects of equipment connection, workshop management, production and operation, which greatly improve the efficiency of pv cell manufacturing and develop product technology.