Electrical standards for solar cells
The graph of the relationship between current and voltage produced by the solar cell is the standard form for representing the cell’s output. This graphical representation is called the IV 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 used in this curve are as follows
Short Circuit Current (ISC)
This is the maximum current (in amperes A) produced by the cell under certain conditions of radiation and the surrounding temperature. The short current is generated when the load circuit is short; this occurs when the ends of the positive and negative wires come into contact.
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):
It is the maximum energy that a cell can produce under specific environmental conditions, 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):
The voltage that produces the most energy also called the « output voltage from the cell ».
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