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General Description of pV/solar system
The rated power of the PV / Solar Module in Watts (Pmax) is derived from the above
values of voltage Vmp and current Imp at this Maximum Power Point (MPP):
• Rated power in Watts, Pmax = Vmp X Imp
Example of I-V Curve and Ratings of a 12 V PV / Solar Panel
Fig. 2.9. Example of I-V Curve and Ratings of a 12 V PV / Solar Panel
The I-V Curve for a typical 12 Volt PV / Solar Panel is shown in Fig. 2.9.
This Maximum Power Point in the example curve given above is where Vmp
is 17 Volts, and the current Imp is 2.5 amps. Therefore, the rated or the maximum
power Wmax in watts is 17 Volts times 2.5 Amps, or 42.5 Watts.
Standard Test Conditions (STC) for Specifying PV / Solar Modules
The I-V curve is also used to compare the performance of PV / Solar Modules.
The curve is, therefore, generated based on the performance under Standard Test
Conditions (STC) of sunlight and device temperature of 25 °C. It assumes there is
no shading on the device. Standard sunlight conditions on a clear day are assumed
to be 1,000 Watts of solar energy per square meter (1000 W/m
sometimes called one sun, or a peak sun. Less than one sun will reduce the current
output of the PV device by a proportional amount. For example, if only one-half sun:
(500 W/m
) is available, the amount of output current is roughly cut in half.
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or 1 kW/m
). This is
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