Solar cell efficiency, marketing efficiency factors
(1) Solar cell efficiency:
When the solar cell is irradiated, the ratio η of the output electric power to the incident light efficiency is called the efficiency of the solar cell, and is also called the photoelectric conversion efficiency. Generally refers to the maximum energy conversion efficiency when the external circuit is connected to the optimal load resistance RL.
If At is replaced by the effective area Aa (also called the active area), that is, the area of the grid line is subtracted from the total area, the calculated efficiency is higher, which should be noted when reading domestic and foreign literature。
Prince of the United States first calculated the theoretical efficiency of silicon solar cells was 21.7%. In the 1970s, M. Wolf made a detailed discussion, and the theoretical efficiency of silicon solar cells was 20% to 22% under AM0 spectral conditions, and later changed to 25% (AM1). .0 spectral condition).
Estimating the theoretical efficiency of a solar cell requires all possible losses from incident light energy to output power. Some of them are losses related to materials and processes, while others are determined by basic physical principles.
(2) Factors affecting efficiency
In summary, to improve the efficiency of the solar cell, it is necessary to increase the three basic parameters of the open circuit voltage Uoc, the short circuit current ISC, and the fill factor FF。 These three parameters are often mutually restrained。 If one of them is raised unilaterally, it may be lowered to the other, so that the overall efficiency has not only increased but decreased。 Therefore, in the selection of materials, design techniques must be considered in full, and strive to maximize the product of the three parameters。