A current-voltage (I-V) curve is meant to display a photovoltaic device's possible combinations of current and voltage output. The x-axis displays voltage, measured in volts, while the y-axis shows current, expressed in amps.
A solar panel, which is a type of photovoltaic device, produces its maximum current when there is no resistance in the circuit. This describes a situation in which the panel short circuits. This maximum current is known as the short circuit current and is abbreviated "Isc". Under this circumstance, the voltage in the circuit is zero.
Conversely, the maximum voltage occurs when there is a break in the circuit. This is called the open circuit voltage, "Voc". Here, the resistance is infinitely high and there is no current. This describes an incomplete circuit. These two extremes and the range between them, are shown on the I-V curve.
The power available from a photovoltaic device at any point along the curve is the product of the current and the voltage at that point. Units of power are called watts. At the short circuit current point, the power output is zero, since the voltage is zero. At the open circuit voltage point, the power output is also zero, because the current is zero.
The maximum power output, as displayed on the I-V curve is thus somewhere between these points. The exact location varies from solar panel to solar panel because each device's I-V curve is a little bit different.
The I-V curve is dependent on the device being under direct sunlight and having a constant device temperature. Standard sunlight conditions on a clear day are 1,000 watts of solar energy per square meter. This is referred to as 'one sun'. Less than one sun will reduce the current output of the PV device by a directly proportional amount.
A solar panel, which is a type of photovoltaic device, produces its maximum current when there is no resistance in the circuit. This describes a situation in which the panel short circuits. This maximum current is known as the short circuit current and is abbreviated "Isc". Under this circumstance, the voltage in the circuit is zero.
Conversely, the maximum voltage occurs when there is a break in the circuit. This is called the open circuit voltage, "Voc". Here, the resistance is infinitely high and there is no current. This describes an incomplete circuit. These two extremes and the range between them, are shown on the I-V curve.
The power available from a photovoltaic device at any point along the curve is the product of the current and the voltage at that point. Units of power are called watts. At the short circuit current point, the power output is zero, since the voltage is zero. At the open circuit voltage point, the power output is also zero, because the current is zero.
The maximum power output, as displayed on the I-V curve is thus somewhere between these points. The exact location varies from solar panel to solar panel because each device's I-V curve is a little bit different.
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