The PV characteristic curve, which is widely known as the I–V curve, is the representation of the electrical behavior describing a solar cell, PV module, PV panel, or an array under different ambient conditions, which are usually provided in a typical manufacturer’s datasheet.
The I–V curve of a PV cell is shown in Figure 6. The star indicates the maximum power point (MPP) of the I–V curve, where the PV will produce its maximum power. At voltages below the MPP, the current is a relative constant as voltage changes such that it acts similar to a current source.
But a photovoltaic array is made up of smaller PV panels interconnected together. Then the I-V curve of a PV array is just a scaled up version of the single solar cell I-V characteristic curve as shown.
Solar cell I-V characteristic curves that summarise the relationship between the current and voltage are generally provided by the panels manufacturer and are given as: = open-circuit voltage – This is the maximum voltage that the array provides when the terminals are not connected to any load (an open circuit condition).
Other important characteristics include how the current varies as a function of the output voltage and as a function of light intensity or irradiance. The current-voltage (I-V) curve for a PV cell shows that the current is essentially constant over a range of output voltages for a specified amount of incident light energy.
The power curve has a a maximum denoted as P MP where the solar cell should be operated to give the maximum power output. It is also denoted as P MAX or maximum power point (MPP) and occurs at a voltage of V MP and a current of I MP. Current voltage (IV) cure of a solar cell.