Explore the impact of solar panel shading on overall performance

The fact that solar panel shading is bad seems obvious. But how bad are they, really? Well, in the worst-case scenario, a small shadow in the corners of one panel could ruin the production of the entire array.

How to solve the shading problem? What are the objects that block sunlight? What about a tree that has grown tall next to your solar system in the last 10 years? In this article, we will look at the solar panel shading problem.

1. How much impact solar panel shading has on power generation

At present, the construction of photovoltaic power stations on residential and industrial and commercial rooftops has become a popular trend, and the amount of power generated by photovoltaic power stations directly affects the final income.

Solar panel shading is one of the most common problems affecting power generation. In many rooftop photovoltaic power plants, many owners often cannot completely avoid shadows in order to be in place at one time during installation.

Because the owners feel that the area shaded by solar panels is not large anyway, the impact should not be very large. But in reality, the power of small shadows is often overlooked.

According to estimates, the slightest shade and power line shading in the distributed pv system can lead to a power station yield of about 20-30%. Under certain conditions, some cells in the photovoltaic system will be blocked by other surrounding objects, causing local shadows.

This will cause some 12v 100ah lithium ion batteries to heat up, creating the so-called "hot spot" phenomenon. If the shadow effect persists for a long time, when the hot spot effect reaches a certain level, the solder joints on the module will melt and destroy the grid, resulting in the scrapping of the entire solar module.

Obviously, the shading seriously affects the service life of the junction box and panels, and at the same time seriously affects power generation and reduces owner's income.

2. Common sources of solar panel shading

• Wires and guardrails

Although the construction scope of photovoltaic power plants is fixed, the surrounding environment of the power station is diverse. Even a very professional system design company will ignore the invisible obstruction of wires and power station guardrails.

• Fix the building

There are two types of buildings here:

Buildings that existed before the construction of the power station were blocked.

Buildings built the day after tomorrow are shaded.

• Nearby plants

When the PV system was first built, there were no plants nearby. But later, new plants grow, and these plants act as a shield for the power station.

• Bird droppings and dust

Photovoltaic modules are often built on rooftops and grounds, and for photovoltaic systems placed outdoors, it is even easier to attract dust. When the module is covered with a layer of dust, don't underestimate this layer of dust, which has a great impact on the power generation of photovoltaic module.

In addition, photovoltaic modules will also become a place for birds to gather, and bird droppings and scattered bird feathers have become frequent visitors to photovoltaic modules.

3. How to effectively avoid solar panel shading

① Pay attention to pre-construction shadow analysis

Before the construction of the photovoltaic system, it is necessary to do a good job of preliminary survey work to determine whether the surrounding high-voltage lines, railings, vegetation, and existing buildings (planned buildings should also be expected in advance) will be blocked, and find ways to eliminate the shielding and change the installation location.

In the survey and installation, the growth year of the plant should be fully considered, and whether the shade, branches and leaves of the tree should be considered to cause shading, and if there is shading, it can be cut down.

There is also a difference in terrain to consider whether the north and south of the module and the east and west of the module cause shading. Different sub-arrays of the same row of squares are occluded. Shadows between floors should also be considered.

② Clean the surface of the PV module

Shadow occlusion is mainly due to the effects of bird droppings, dust, shade, etc. So first of all, we can choose a suitable location to install the photovoltaic modules, and try not to install the modules in a sheltered place.

When it's unavoidable, choosing the right way to place components can mitigate the effects of shadows. In daily operation and maintenance, pay attention to the cleaning of photovoltaic modules, and remove foreign objects such as dust accumulation in a timely manner.

③ Avoid man-made occlusion

For example, installing a fence and erecting a bird repellent pole in order to drive away birds is a well-intentioned and positive move, but it has a counterproductive effect.

There are also people who lack knowledge of photovoltaic operation and maintenance, and make mistakes such as drying clothes and vegetables in photovoltaic modules, which will invisibly bring shelter to the power station.

④ Select multi-channel MPPT inverter

From the perspective of the system itself, the implementation of multi-channel MPPT will reduce the impact of shadow occlusion. For example, a solar microinverter system is designed with fully parallel circuits, with each module having its own MPPT for maximum power output.

The partial shading of shadows, dust, and leaves on the solar panel no longer has a short board effect, eliminating the mismatch caused by different module shading, orientation and angle, and greatly improving the power generation.

However, based on this type of system, each solar panel is equipped with an 3000w inverter, and the cost is also relatively high. It can only be said that, based on the site conditions and basic calculations, if the cost budget allows, the use of such a system can avoid the limitations of solar panel shading and bring higher power generation efficiency and benefits, making it is a good choice.

⑤ Brand and types are matter

The ability of PV modules to perform well in low-light conditions and in the shadows is one of the selling points. Monolithic solar cells have good shading resistance.

Some PV modules have bypass diodes that allow them to maintain higher efficiency in the shade. Finally, consider connecting solar panels in parallel. So that the performance of the panel will not affect the other panels. Keep in mind that this type of connection voltage remains low, but the current is cumulative for all panels.

4. Conclusion

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