Shading of photovoltaic panels reduces the performance of photovoltaics. What can be done about it?

A chimney, a neighbor's tree, or even a building across the street. Shading of a single photovoltaic panel is enough to significantly reduce the performance of the entire system. Long-term shading of panels not only affects performance but can also cause panel degradation. The installation company should take this into account when designing a photovoltaic system. If shading cannot be avoided, there are solutions in the form of bypass diodes or power optimizers that help mitigate the effects.

Why is shading a problem?
A photovoltaic power plant consists of modules that are most often connected in series. In this case, the performance of the entire chain is affected by the weakest link – if one panel is shaded, the current in the entire series is reduced.

Any shading leads to a decrease in photovoltaic performance, but if it is significant (e.g., it affects key parts of the panel), it can reduce electricity production by tens of percent. This is then reflected in a longer return on investment.

We divide shading into two main categories:

• Hard shading: caused by solid objects (e.g., a chimney or neighboring building). It has clearly defined edges and can activate bypass diodes, which mitigate its impact.
• Soft shading: caused by scattered light from moving branches, distant trees, or clouds. This type of shading does not usually activate bypass diodes, which means that the reduction in power is transferred to the entire string of panels and can cause higher losses.

How to deal with shading of photovoltaics
When designing a photovoltaic system, it is essential to thoroughly analyze possible shading. We recommend using professional shading simulations to optimize panel placement and minimize power losses.

One modern solution for reducing the impact of shading is half-cut panels. These panels are divided into two independent halves, which means that if one part is shaded, the other can still generate energy efficiently. This reduces losses compared to conventional panels.

Bypass diodes
Bypass diodes are an important component of photovoltaic panels that minimize power loss in the event of shading. If a shadow covers an entire section of the panel (usually one third), the bypass diodes are activated and redirect the electrical current away from that section, preventing overheating and power loss.

Bypass diodes are particularly effective in hard shading, where the panel is clearly separated by the shadow. However, in soft shading, bypass diodes are not usually activated because part of the panel still generates current, which leads to a reduction in the output of the entire string.

Advantages:

• Effective in hard shading of a large part of the panel
• Inexpensive solution integrated into photovoltaic modules

Disadvantages:

• Ineffective in soft shading
• Local overheating and degradation may occur when a smaller part of the panel is shaded

Power optimizers
Power optimizers are devices that are installed on individual panels and allow them to operate independently of others within a single string. This means that if one panel is shaded, the optimizer adjusts its output so that it does not affect the other panels in the string.

Optimizers are effective in both hard and soft shading because they allow each panel to be controlled independently. This significantly improves the overall performance of the system, especially if there is uneven lighting or different panel orientations in the installation.

Advantages

• Effective in both hard and soft shading
• Allows independent optimization of each panel, maximizing system performance

Disadvantages

• Higher price
• Risk of failure due to added complexity and components

You can ensure the long-term performance and service life of photovoltaics mainly by placing the panels in an unshaded location. However, if shading cannot be completely avoided, it is important to choose the right technology to minimize losses.

Choose from our wide rangeOur range includes a wide variety of solar panels from leading global manufacturers, many of which are the half-cut panels mentioned above. You will also find optimizers in our range.