How does shading specifically affect series versus parallel wiring?

Series Wiring and Shading

When connected in series, shading a single panel reduces the overall system voltage. For example, a system with three 60-cell panels connected in series (480V system voltage) will see a 10% reduction in voltage (48V) if one panel is shaded, due to the reduced voltage output of the shaded panel. This voltage drop can lead to reduced efficiency and increased stress on the system.

Parallel Wiring and Shading

In contrast, parallel wiring allows each panel to maintain its voltage, even when shaded. If a single panel is shaded in a parallel system, the remaining panels will continue to operate at full voltage (480V in this example). However, the shaded panel’s reduced current output will be isolated from the rest of the system, eliminating the risk of reduced voltage.

Managing Shading in Solar Systems

To minimize the impact of shading, solar systems should be designed with shading considerations in mind. This includes orienting panels to minimize shading, using panel-level monitoring to detect shading events, and selecting inverters that can handle reduced voltage inputs. In series systems, designers may need to consider using DC-DC converters or other voltage regulators to maintain system voltage when shading occurs.