Performance parameters of solar cells.

1, open circuit voltage

Open circuit voltage UOC: that is, the solar cell is exposed to AM1.5 spectral conditions and 100 mW/cm2 light source intensity, and the output voltage value of the solar cell is open at both ends.

2, short circuit current

Short-circuit current ISC: It is the current value that flows through both ends of the solar cell when the solar cell is exposed to AM1.5 spectral conditions and 100 mW/cm2 light source intensity.

3. Maximum output power

The working voltage and current of solar cells change with the load resistance, and the working voltage and current values corresponding to different resistance values are made into curves to obtain the volt-ampere characteristic curve of solar cells. If the selected load resistance value can maximize the product of output voltage and current, the maximum output power can be obtained, which is represented by the symbol Pm. At this time, the working voltage and working current are called the best working voltage and the best working current, which are represented by the symbols Um and Im respectively.

4. Fill factor

Another important parameter for solar cells is the fill factor FF (fill factor), which is the ratio of the maximum output power to the product of the open circuit voltage and short circuit current.

FF: is an important indicator to measure the output characteristics of solar cells, is the representative of the solar cell with the best load, can output the maximum power characteristics, the greater the value of the solar cell output power. FF is always less than 1. The series and parallel resistors have great influence on the filling factor. The larger the series resistance is, the more the short circuit current drops and the more the filling factor decreases. The smaller the shunt resistance, the greater its component current, resulting in the more the open circuit voltage drops, and the more the fill factor drops accordingly.

5. Conversion efficiency

The conversion efficiency of a solar cell refers to the maximum energy conversion efficiency when the optimal load resistance is connected on the external circuit, and is equal to the ratio of the output power of the solar cell to the energy incident on the surface of the solar cell. The photoelectric conversion efficiency of solar cell is an important parameter to measure the quality and technical level of the battery, which is related to the structure of the battery, junction characteristics, material properties, working temperature, radiation damage of radioactive particles and environmental changes.