R & D and equipment development
Grid Parity is Our Goal
Advantages of HDT Solar Cells Technologies
1、Low processing temperature:All processes for HDT solar cells are carried out at temperatures below 220°C；
2、Hetero-junction emitter:Band engineering technology improves the quality of the amorphous silicon and widens its band gap, making the layer more transparent, resulting in Isc and Voc. The world record efficiency for this type of solar cells has reached to 26.3%；
3、Low power-temperature coefficient:The power-temperature coefficient of HDT solar cell is less than ~-0.28%/ºC， making it more suitable working in hot outdoor environment.
4、Readiness of flexible solar cells technology：GS-Solar developed the technology to fabricate the very thin silicon solar cells.
5、Double-sided module technology：HDT solar cell has a double-sided structure, which can receive the sunlight from both sides, well for making the glass-glass modules. With optimal positioning on the ground, the modules could generate ~10% more output power.
Functions of Amorphous Silicon
HDT solar cell contains a total of four layers of silicon film, in which P-type and N-type silicon doped layer as the emitter and back electrode field of the cell to build the internal electric field of the solar cell, with the thickness of about 5nm.
The main role of the intrinsic silicon layer in the front and back of the monocrystalline silicon wafer is to passivate the surface of the monocrystalline silicon (Note: the surface of monocrystalline silicon due to the long-term structure of the crystal structure damage, resulting in a large number of surface defects), increase the minority carrier lifetime, and decrease the recombination of minority carrier on the interface.
The intrinsic silicon layer of HDT solar cell has a thickness of 10nm or less, usually about 5nm. While in the traditional silicon thin film solar cells, the intrinsic silicon as the light absorption layer, the thickness is generally between 200nm ~ 300nm, the difference is about 50 times. Thus, the light-induced degradation effect in silicon thin film solar cells is recognized as not exist in HDT solar cells.
Road Map for Increasing Conversion Efficiency of HDT Solar Cells
1、Reduction of Optical Loss：Reduce the textured surface reflection / Reduce the light absorption by TCO layer and amorphous silicon / Decrease the grid covering area by increasing its aspect ratio
2、Reduction of Surface Recombination Velocity：Improve the cleaning process for textured surface／Optimize the doping concentration of the doped amorphous silicon／Improve the quality of intrinsic layer
3、Reduction of Series Resistance：Increase the conductivity of TCO layer／Reduce the contact resistance between TCO layer and doped amorphous silicon
Unique Texturing and Surface Cleaning Processes
The use of non-IPA-containing texturing additive improves the stability of the texturing and extends the lifetime of the solution.
The removing the surface layer completely eliminates the mechanical damage on the wafer surface, and effectively controls the size and size distribution of the pyramids.
A unique cleaning process is developed to ensure the cleanliness of silicon surface before passivation; an intellectual proprietary process has been developed for pyramids sharpening treatment method to avail the silicon films to cover evenly on the pyramids.
Advanced Technology of Metallization Process
GS-solar brings in the concept of semiconductor microchip technology, using special equipment to complete high-conductivity metal fine line, and provides customers with the best technology to achieve equipment and operating costs far lower than the traditional low-temperature screen printing of Ag.
The conductivity of high conductivity material is 10 times the conductivity of silver, and the metal fine line is easy to weld, the line width can be controlled below 40μm.
Innovated Stable & High Yield PECVD Equipment
The proprietary high-end PECVD equipment designed and developed by GS-Solar is featured by its high capacity, stable operation, continuous batch production, and stable repeatability.
GS-Solar’s high-end PECVD equipment adopts a unique RF electrode design with adjustable RF electrode gap, low RF power ignition and stability, realizing good carrier temperature uniformity and thickness uniformity of the film deposited.
The process window is wide, and after low-power film passivation, the minority carrier lifetime of crystalline silicon can be close to its intrinsic lifetime.
Independently Developed Stable & High-Yield PVD Equipment
GS-Solar independently developed double-sided deposition PVD equipment with rotary target, which improved the target utilization rate up to 80% and reduced the maintenance time by 40%.
GS-Solar’s PVD equipment uses a unique cathode target design, resulting in stable and repeatable sputtering process. The uptime of the equipment is over 90% and its through-put is over 3000 wafers per hour.
The pre-heat chamber and the deposition chamber are all equipped with in-situ heating element that can heat substrate up to 200ºC during TCO thin film deposition. The film thickness variation is controlled within 5%.
Strategy for Technology leadership
Focus on innovative technologies that have real market potential. Develop new manufacturing process for low cost, high efficiency solar cells.
Attract global photovoltaic industry technology leaders and build globally influential R&D team.
Attract capital from top notch global investors; continue to invest in R&D and innovation.
Build a patent portfolio that has true technology and market value. Today, we’ve acquired over 150 patents through independent R&D.
Principle of Lowest Cost
Seek to provide the end users of our solar cells with the lowest TCO (total cost of ownership).
Seek to provide our clients the highest ROI (return on investment) on a complete solar cell production line.
Reduce cost without making any compromises on high quality
Photovoltaic industry is growing exponentially and the competition in the industry is heated up. Only the companies who possess strong R&D and innovation competence can become global industry leaders.