At present, solar street lights have been installed in most cities and even rural streets in my country. As a new type of street lamp that saves energy, solar street lights have been widely recognized by the society, and the state has also invested huge manpower and material resources to support this aspect. So that the solar street light has a long-term and benign development, so what are the performance parameters that affect the solar street light battery module?
(1) Short circuit current (Isc)
When the solar cell is placed under the illumination of a standard light source and the output end of the solar cell module is short-circuited, the current flowing through both ends of the solar cell is the short-circuit current of the cell module. The method of measuring the short-circuit current is to connect the two ends of the solar cell with an ammeter whose internal resistance is less than 1Ω. The short-circuit current varies with the light intensity.
(2) Peak current (Im)
The peak current is also called the maximum working current or the optimum working current. The peak current refers to the working current when the solar cell module outputs the maximum power, and the unit of the peak current is A.
(3) Peak voltage (Um)
The peak voltage is also called the maximum working voltage or the optimum working voltage. The peak voltage refers to the working voltage when the solar cell outputs the maximum power, and the unit of the peak voltage is V. The peak voltage of the module varies with the increase or decrease of the number of cells in series. The peak voltage of the module with 36 cells in series is 17-17.5V.
(4) Open circuit voltage (Uoc)
Under the illumination of the light source, when both ends are open (the positive and negative poles of the solar cell module are not connected to the load), the output voltage of the solar cell is the open-circuit voltage. The unit of open circuit voltage is V. The open circuit voltage of a solar cell module changes with the increase or decrease of the number of cells in series. The open circuit voltage of a module with 36 cells in series is about 21V. The open circuit voltage of the battery can be measured with a high internal resistance DC millivoltmeter.
(5) Maximum output power
If the selected load resistance value can maximize the product of the output voltage and current, the maximum output power can be obtained, which is represented by the symbol Pm. The working voltage and working current at this time are called the optimum working voltage and optimum working current, which are represented by symbols Um and Im respectively, Pm=UmIm
The product of rated voltage and rated current is rated power. The rated output power is the maximum output power under normal conditions (can work for a long time). The rated output power of a solar cell is related to the conversion efficiency. Generally speaking, the higher the conversion efficiency of a battery module per unit area, the greater the output power. The current conversion efficiency of solar cells is generally between 14 percent and 17 percent . The output power of each square centimeter of cells is 14 to 16mW, and the output power of solar cell modules per square meter is about 120W.
(6) Peak power (Pm)
Peak power is also called maximum output power or optimum output power. Peak power refers to the maximum output power of the solar cell module under normal working or test conditions, that is, the product of the peak current and the peak voltage: Pn=ImUm. The unit of peak power is watts. The peak power of a solar cell module depends on the solar irradiance, the solar spectral distribution and the operating temperature of the module, so the measurement of the solar cell module should be carried out under standard conditions. The test standard of solar cells: the spectral distribution when the air quality is AM1.5 (for specific regulations, please refer to the relevant national and international standards in my country), the solar radiation emitted by humans is 1000W/m², and the temperature is 25 degree . The output power of the solar cell under this condition is defined as the peak power of the solar cell.
(7) Fill factor (ff)
It refers to the ratio of the maximum power of the solar cell module to the product of the open-circuit voltage and the short-circuit current: f=Pm/(IsU.). It reflects the variation characteristics of the output power of the battery with the load, and the fill factor is one of the important parameters to characterize the pros and cons of solar cells. The larger the fill factor, the better the solar cell performance.
