How is the current affected if one panel in a series connection has reduced performance?

In a series connection of solar panels, the same current flows through each panel. This means that the current produced by the entire string of panels is determined by the panel with the lowest performance. When one panel experiences reduced performance—such as due to shading, a malfunction, or any other issue—it creates a bottleneck in the current flow.

The current in a series circuit cannot exceed the value of the weakest link. Therefore, if one panel's performance decreases, the overall current produced by the string will also decrease. This reduction occurs because all the panels must operate at the same current level, and the underperforming panel limits the entire system's output.

Consequently, the current will be diminished to that of the affected panel, leading to less power generation from the entire series. Thus, the correct understanding is that the overall current decreases when one panel in a series connection has reduced performance.