Part 1 Background
In the past decade, the growth of the global photovoltaics (PV) industry has been impressive. Great technological developments have been made in both laboratory and industrial mass production. As shown in Figure 1, emerging technologies have appeared in the past decade or so, meanwhile, the efficiencies of cells with different technologies have rapidly increased. The efficiency of single crystal silicon cell has reached a laboratory efficiency of 26.7%. Another promising emerging technology is Perovskite and Si tandem cell technology, which has reached a laboratory efficiency of 29.8%.
Figure 1 Best Research-cell Efficiencies
However, the mainstream technology in the industry is still single crystal silicon solar cell technology. With the development and maturity of p-type PERC technology, there is limited space for further improvement of cell efficiency. On the other hand, the efficiency of n-type silicon cell has been improving rapidly in recent years. The production capacity of n-type cell is expected to expand in the next 1-2 years, as maturity of technology and equipment increases and cost decreases. The n-type PV module is expected to become the mainstream product in the market in 5 years, as shown in Figure 2.
Figure 2 2021-2030 Market Share of Modules with Different Tech
Part 2 Introduction of DeepBlue 4.0 X
Now, along with the progress of the whole industry chain, we have come to the first year of industrialization of n-type products. What kind of PV module are customers seeking in the n-type era?
On May 18th 2020, JA Solar launched the DeepBlue 3.0 series products, starting a new chapter of 182 modules. DeepBlue 3.0 has now become one of the mainstream products in the market. JA Solar has never stopped innovating and surpassing itself, and is committed to creating PV products with real core technical competitiveness. Now, two years later after DeepBlue 3.0 was born, we are once again witnessing the birth of a new product - DeepBlue 4.0 X. It is a product that inherits the value of "customer-centric" of the DeepBlue series; it is a top product based on the latest n- type high-efficiency cell and module technologies; it is a product that leads the industry in the era of high efficiency and opens an infinite future; it is a breakthrough product born at the right time.
Figure 3 DeepBlue 4.0 X
Core features and advantages of DeepBlue 4.0 X are shown below.
1. BYCIUM+ n-type high-efficiency bifacial cells
DeepBlue 4.0 X is JA Solar's first official n-type product, but JA Solar has been developing the n-type solar cell for 13 years and have gone through multiple iterations. The cell efficiency has been continuously improved. The core technologies of high-efficiency n-type Bycium+ solar cell cover wafer, cell and process.
1) Wafer for BYCIUM+ cell: the wafers are JA Solar's self-developed phosphorus-doped n-type wafers. The minority carrier lifetime is much higher, at the millisecond level (over 50 times of p-type wafer). The n-type cell needs to go through an ultra-high temperature process. In order to eliminate the negative effects of oxygen in the high temperature environment, we effectively reduce the oxygen content in the silicon wafer to less than 12 ppm, and this can make the wafer meet the requirements of n-type cells which is highly sensitive to oxygen. In terms of wafer size, JA Solar will continue with the proven M10 wafer size which has been adopted for our p-type products. This ensures that the module size is exactly the same as the P-type module, so it is convenient for module installation and application.
2) Surface passivation structure: for many years, the efficient way for improving cell efficacy is better surface passivation. The passivation of the front and rear surfaces of the BYCIUM+ cell has been optimally upgraded. As shown in Figure 4, with a combination of chemical and field passivation effects on both surfaces as well as an innovative passivation contact at the rear surface, it is able to reduce the surface recombination to near zero. In addition, the combination of ultra-thin fingers and double-sided anti-reflection coating is also adopted to allow solar cells to harness more light energy. The cell Voc exceeds 720mv, and the mass-production efficiency is over 24.8%.
Figure 4 Structure of BYCIUM+ n-type high-efficiency bifacial cell
2. Gapless Flexible Interconnection (GFI) Technology
The advanced n-type cell technology contributes greatly to improving the efficiency of the final module product. In order to achieve higher module efficiency, DeepBlue 4.0 X also employs a new-generation high-density module technology - Gapless Flexible Interconnection (GFI) technology. As shown in Figure 5, the GFI technology eliminates the micro crack problem for high-density module by adopting regular round ribbon together with a special buffer design which deals with mechanical stress at the cell connections. It ensures stable and reliable long-term power generation performance. Besides, GFI is totally compatible with both monofacial and bifacial modules. Through GFI technology, module power can be increased by more than 5 watts and module efficiency increased by at least 0.2%.
Figure 5 Gapless Flexible Interconnection (GFI) Module
3. Excellent Reliability of DeepBlue 4.0 X
The IEC standards require a module power loss below 5% after the tests. As can be seen from Figure 6, the power loss of DeepBlue 4.0 X is only around 2%, which is far below the IEC standards. This demonstrates the excellent reliability of DeepBlue 4.0 X, and ensures the power generation performance during the 30-year lifetime.
Figure 6 Excellent Reliability of DeepBlue 4.0 X
4. Higher power and efficiency
With the advanced cell and module technologies, DeepBlue 4.0 X has higher power density. Compared with p-type module, the power of DeepBlue 4.0 X is about 25W higher and module efficiency is about 1% higher (Figure 7).
Figure 7 Power Comparison of n-type and p-type Module
5. Lower Degradation
When we evaluate a module product, in addition to power and efficiency, the module's power generation performance is also critical, because this affects the customer's benefits from the PV power station. Power generation performance is mainly affected by some factors, including degradation, temperature effect, bifaciality, low light performance and so on.
JA Solar provides a 30-year power output warranty (Figure 8), with a first-year degradation of 1%, and linear degradation rate of 0.4% every year. After 30 years, the power of DeepBlue 4.0 X module can still be at least 87.4% of the initial value, which is 2.4% higher than conventional p-type module. Because of this lower degradation rate, the n-type module generates 1.8% more electricity in 30 years, compared with p-type module.
Figure 8 Power Degradation of n-type and p-type Module
6. Lower Temperature Influence
As known, higher temperature brings down the power output of PV modules. For the BYCIUM+ cell, because its open circuit voltage can be as high as about 715 mV, so finally the DeepBlue 4.0 X has a better temperature coefficient. The temperature coefficient of power is -0.30%/°C, while it is -0.35%/°C for p-type module. This excellent temperature coefficient allows the DeepBlue 4.0 X to generate more power in high temperature environments. As can be seen from Figure 9, thanks to the excellent temperature coefficient, the DeepBlue 4.0 X generates about 2% more electricity than p-type module in one year, if we suppose that the operating temperature is 65°C.
Figure 9 Effect of Temperature on Power Output
7. Higher Bifacial Benefits
Under standard illumination of 1000 W/m2, DeepBlue 4.0 X has a higher bifaciality of 80%, while the typical value for p-type module is only 70%. If we suppose that the irradiation at the back side is 10% of the front side, the extra bifacial gain is about 0.9% for DeepBlue 4.0 X compared with p-type module.
8. Better Low Light Performance
Because of lower internal resistance and higher minority carrier lifetime of n-type cells, DeepBlue 4.0 X has a better performance under low irradiation. The test result shows (Figure 10) when the irradiation is below 600 W/m², n-type module obviously produces more electricity than p-type. So, the energy gain in the morning or evening would be about 0.2%.
Figure 10 n/p Low-light Relative Power Gain
The following picture (Figure 11) summarizes the features and benefits of the DeepBlue 4.0 X module.
Figure 11 Features and Benefits of DeepBlue 4.0 X
Part 3 Data from Demonstration Project and Simulation
"Maximizing customer value" is the core design concept of DeepBlue 4.0 X. The excellent power generation performance of n-type module perfectly improves the customer value. JA Solar and TÜV NORD launched a one-year (February 2021-February 2022) energy yield test at China Photovoltaic Test Center, Yinchuan base (North west China). The results (Figure 12) from this demonstration project show that the power generation of n-type modules is 3.9% higher than that of p-type modules. Excellent power generation performance is essential for excellent module products.
Figure 12 Power Generation Performance (n-type vs p-type)
BOS and LCOE are the core indicators to assess the customer value for PV power plant. We made simulations of a 100MW project in Dubai to compare the BOS and LCOE of DeepBlue 4.0 X and p-type module. The results show the BOS for DeepBlue 4.0 X is 2.1% lower, and LCOE is 4.6% lower than p-type module (Figure 13). The DeepBlue 4.0 X module will bring significant gain of the PV system.
Figure 13 Comparison of BOS and LCOE
In addition, for different regions, we also did corresponding simulations (Figure 14). LCOE of n-type module is better than that of p-type, and the average difference is about 2.3%.
Figure 14 Comparison of LCOE of n-type and p-type Modules in Different Regions
Part 4 Closing
"High quality, high efficiency, low cost" is the eternal theme of the PV industry. The cost will directly affect the large-scale commercial applications. The cell manufacturing cost of DeepBlue 4.0 X is still a little higher than p-type product. However, with further improvement of technology and production capacity, we believe that, the cost of DeepBlue 4.0 X will be more competitive in the next 1-2 years. In the future, JA Solar will continue to provide customers with PV products with the best LCOE and highest customer value, and contribute to facilitate the achievement of carbon neutrality goals.
