The following is a presentation given by Sewon Tech and data related to RSC.
1. What is RSC?
It is an ultra-high efficient solar cell that is adapted on crystalline silicon and reaches over 200% output power (over 33% of efficiency on Multi-Si Cell) into the condition of same unit area comparing the conventional solar cell.
It has 3-dimensional form that can significantly increase the surface area as it absorbs the solar light and resorbs the reflected sunlight.
2. RSC photovoltaic mechanism
RSC is a 3D-structured wafer to absorb the reflected light one more time, and especially has a very low reflectance in short wavelength range than that of the conventional solar cell.
3. Design and wafer cutting
A conventional solar cell has a flat shape. However, RSC formed a 3D-structured wafer surface through a special wafer sawing machine that has a specialized wafer cutting technology. By doing this, the above mechanism can be achieved on the wafer surface.
4. Reflectance measurement
A. There is no big difference about reflectance before texturing between RSC wafer and planar wafer, but there was an obviously decrease after texturing for wave wafer; it reaches up to AVG 20.41%.
B. When the light is inclined 10° at a right angle for each specimen textured, variable range at (b) RSC wafer is narrower than (a) planar wafer.
C. When reflectance was measured after AR-Coating process under the same condition, RSC wafer shows low reflectance in the short wavelength range of 400~600nm. (Measured at K university in China)(b) RSC wafer is narrower than (a) planar wafer.
D. As a result of measuring reflectance at 500nm, which has highest density of energy under sunlight, RSC shows noticeably low reflectance.(Measured at S university in Korea).
E. Spectrum of sunlight and Xe-Lamp were compared first and the reflectance graph of conventional flat wafer with AR-Coating and RSC water was overlapped for comparison.
RSC Shows overall lower reflectance than that of the conventional cell from reflectance analysis, and especially shows high light absorbance at short-wavelength range of sunlight.
5. Measurement of Jsc & Power
To evaluate performance of the manufactured RSC, the current density of conventional flat type solar cell with efficiency of 16.6% and RSC was measured in 30-minute interval from 10:30 in the morning to noon on a sunny day under sunlight. As a result of reviewing current density per unit area (Jsc), the difference from conventional cell grows greater as the stronger the sunlight, the more significant the characteristics of RSC.
The current density per unit area of RSC, Jsc and power density were found to be over 200% greater than the conventional solar cell under the sunlight. (If converted to efficiency, over 33% expected.)
6. Conclusion
Sewon Tech succeeded in processing a 3D-structured wafer, which started from a basic idea that if crystalline silicon solar cell has a curved surface rather than a flat surface then it will have broader area of light absorbency and the generating efficiency will increase through trapping of light. The processed 3D-structured wafer was used to produce a cell under the conventional production line through the same process.
As shown in the above data, primarily reflectance was lower in the 3D-structured wafer than the conventional wafer and secondarily it was confirmed changes in incidence angle of light do not have a great influence in absorbing capacity. Thirdly, it was confirmed that it has about 3 times the light absorbency of the conventional planar cell at a short wavelength area of 500nm. When concluding from such results, RSC has shown the minimum of over twice the generating effect of the conventional solar cell.
7. Vision
Sewon Tech will achieve an energy revolution of allowing unlimited use of cheap and safe energy for all over the world by providing a solar cell with over 40% of efficiency in multi-silicon through optimization of a RSC manufacturing technology and mass production with a ambitious partner.
