Solar energy


I-V curve



An I-V curve (short for ‘current-voltage characteristic curve‘), is a graphical representation of the relationship between the voltage applied across an electrical device and the current flowing through it. It is one of the most common methods of determining how an electrical device functions in a circuit.

In Solar panels, l is the standard form for representing the cell’s output. This graphical representation is also called the I-V Curve, and this curve displays a complete picture of all the possible combinations of current and voltage produced by the cell under specific environmental conditions such as radiation, surrounding air mass, and temperature.

The main terms shown in this curve are as follows

  • Short Circuit Current (ISC):

It is the maximum current that the module can reach in the absence of a load or a load with a value close to zero One of the important criteria or tests for expressing the quality of a module. That is, it is the current passing through the solar cell To an external circuit without load (or resistance), which is the maximum current a solar cell can produce from radiation. The solar system, often proportional to the solar radiation

  • Open Circuit Voltage (Voc) 

Equals to 0.58V: it is the maximum voltage that the cell generates under certain conditions of light and temperature; it is the voltage when the cell is not connected to any loads, so the current output is zero, and the energy produced at this stage is also zero.


  • Maximum Power (P.max):

The maximum power a module can produce under specific environmental conditions,, which varies from one module to another, and the greater this ability, the greater the size of the module. and the maximum achievable power on the curve is called the maximum power point of the solar panel (MPP).

  • Current at Maximum Power (Imp) :

is the current that leads to the maximum amount of energy. It is also called the “current rate produced by the cell.”

  • The voltage at Maximum Power (Vmp)

It is the voltage of the module in the case of charging or the presence of a load through which it is possible to know the system of the module; If the module is 12 volts, this voltage is 17 volts or 18 volts, and in a 24-volt system, these voltages are within 30 volts.

The value of both current and voltage at the maximum energy produced by the solar cell is the key by which we know the efficiency of the solar panel. 
The maximum energy of the solar panel can be calculated at this point through the following calculation:

 Vmp × Imp = P.max

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