Can prolonged shading affect series performance more than parallel?

Series Wiring and Shading Effects

Series-wired solar panels are connected end-to-end, meaning that any shading on one panel will affect the entire string. This is because the current from each panel adds up to the total string current, and shading on any one panel will reduce its current output, causing the entire string to be reduced. As a result, a 10% shading on one panel can reduce the string’s voltage by up to 10% due to the current drop, even if the overall solar irradiance remains high.

Effects of Shading on Series Performance

In a series-wired system, the voltage is additive, but current is subtractive. If one panel is shaded, its output current is reduced, which in turn reduces the total string current. To calculate the impact, consider this example: a 10% shading loss on a 100W panel reduces its output to 90W. If the system is wired in series with 10 panels, each producing 100W, the total string current will be 1000W. With one panel shaded at 10%, the total string current will drop to 900W, resulting in a loss of 100W.

Shading Mitigation Techniques

To minimize the effects of shading on series performance, consider the following techniques:

• Implement a string monitoring system to track individual panel performance and detect shading issues.
• Use a DC power optimizer, which can adjust the output of each panel to match the remaining panels in the string, maximizing overall system performance.
• Consider reconfiguring the system to use parallel wiring, which distributes the current from each panel, minimizing the impact of shading on individual panels.