I-V Curves

The I-V curve describes the electrical behavior of a photovoltaic module by showing the relationship between the current (\(I\)) it can deliver and the voltage (\(V\)) across its terminals. Electrical power is simply the product of these two quantities, \(P = I \times V\). When the terminals are short-circuited, the module delivers its maximum current, known as the short-circuit current. When the terminals are open, the module reaches its maximum voltage, known as the open-circuit voltage. Between these two extremes lies a characteristic curve that reflects the balance between current and voltage for a given set of operating conditions.

The most important point on the I-V curve is the maximum power point (MPP)—the combination of current and voltage at which power output is maximized. Since irradiance and temperature vary over time, the position of the MPP also shifts. Photovoltaic systems use maximum power point tracking (MPPT) to maintain the operating point near this optimum. The shape of the I-V curve and the position of the MPP thus provide a practical means of understanding and predicting the performance of a photovoltaic module under real operating conditions.