The solar panel parameters are given by the manufacturer under STC (Standard Test conditions). Under STC, the corresponding solar radiation is equal to 1000W/m2, the battery operating temperature is equal to 25°C, and Am is equal to 1.5.
The parameters of solar cells are as follows:
ISC, short circuit current. Short-circuit current is the maximum current produced by A solar panel and is measured in amperes (A) or milliamps (mA). The value of the short circuit depends on the area of the solar panel, the amount of solar radiation falling on the solar panel, the battery technology, etc. Sometimes manufacturers give the current density instead of the current value. The current density is denoted by "J", and the short-circuit current density is denoted by "JSC". The relationship between them can be expressed by the following formula: JSC = ISC/A. For example: a solar panel at STC has a current density of 50mA/cm2 and an area of 300 cm2. Then the short-circuit current can be determined as follows: ISC=JSC * area =50*300=15000mA=15A.
VOC, open circuit voltage. The open circuit voltage is the maximum voltage that the solar panel can generate under the open circuit condition. It is measured in volts (V) or millivolts (mV). The value of VOC depends on the solar panel technology and operating temperature.
PM, peak power. The unit of measurement is usually W. The maximum power represents the maximum power that the solar panel can generate under the STC. It is measured in Wpeak or simply WP. In addition to the STC, solar panels and 10 awg solar cable also have PM at different radiosity and operating temperature values. The solar panel can operate under different combinations of currents and voltages. But it can only produce the maximum power PM for a specific combination of voltage and current, which can be expressed by the following formula: PM = IM × VM.
Imp, current at maximum power point. It represents the current generated when the solar panel is operating at its maximum power point. Its value is always less than the short circuit current (ISC). It is measured in amperes (A) or milliamps (mA).
Vmp, voltage at maximum power point. It represents the voltage generated when the solar panel is operating at its maximum power point. It is measured in volts (V) or millivolts (mV).
FF (%), the fill factor, which is expressed as a percentage (%), the higher the fill factor, the better the battery. The fill factor is defined as the maximum power generated (at MPP) divided by the product of ISC and VOC. As we can see, the fill factor is always less than 1. Because of the difficulty of measuring the conversion efficiency quickly, filling factors are usually measured instead. It is usually expressed by the following formula: FF = Pm/(Isc ×Voc) , efficiency. The efficiency of a solar panel is defined as the maximum power output (PM) divided by the power input (PIN). It is measured as a percentage (%), which indicates that this percentage of input solar power is converted into electricity. The input power is the power density. The efficiency can be calculated as follows: ǫ = PM/(PIN × Area)