What are the shadows and dirt of photovoltaic modules?

We know that photovoltaic modules have shadows and dirt. So, what are the shadows and dirt of photovoltaic modules? Let's go take a look next.

Here is the content list:

• Shadow

• Dirt

Shadow

The electrical output of photovoltaic modules is extremely sensitive to shadows ("Christmas light effect"). Even if a small part of the cell, module, or array of the photovoltaic module is shaded, the rest of the photovoltaic module is in the sun, due to the internal "short circuit" of the photovoltaic module (electrons reverse through the shadow part of the PN junction). If the current of the photovoltaic module drawn from the series battery string is not greater than the current of the photovoltaic module that the shadow cell can produce, the current (and therefore the power) of the photovoltaic module produced by the battery string is limited. If the cells of other photovoltaic modules in the string provide sufficient voltage, the current will be forced through the cells of the photovoltaic module by breaking the nodes in the shaded part. The breakdown voltage of ordinary batteries is between 10 and 30 volts. The shadow unit of the photovoltaic module is not to increase the power generated by the panel, but to absorb the power and convert it into heat. Since the reverse voltage of the cell of the shaded photovoltaic module is much greater than the forward voltage of the cell of the light-emitting photovoltaic module, a cell of a shaded photovoltaic module can absorb the power of many other cells in the string, thereby disproportionately affecting the panel output. For example, at a certain current level, the battery of a shaded photovoltaic module may drop by 8 volts instead of increasing by 0.5 volts. Therefore, the photovoltaic device mustn't be blocked by trees or other obstacles.

Several methods have been developed to determine the use of shadows in two large areas, from the loss of trees to the photovoltaic system lidar, and a separate system-level 3D modeling software is being used. Most modules have bypass diodes between each battery or battery string, which can minimize the impact of shadows and only lose power in the shadows of the array. The main job of the bypass diode is to eliminate the hot spots formed on the unit, which will further damage the array and cause a fire.

Dirt

Sunlight will be absorbed by dust, snow, or other impurities on the surface of photovoltaic modules (collectively referred to as dirt). Pollution will reduce the light irradiated on the cell, thereby reducing the power output of the photovoltaic module. The fouling loss of photovoltaic modules will accumulate over time, and if the photovoltaic modules are not sufficiently cleaned, they will become very large. In 2018, the global annual energy loss of photovoltaic modules due to pollution is estimated to be at least 3%-4%. However, pollution losses vary greatly in different regions and regions. Keeping the surface of the module clean will improve the output performance during the entire life cycle of the photovoltaic module. In snowy areas (in a study conducted), cleaning flat-mounted solar panels after 15 months increased their production by nearly 100%. However, the 5° tilted array was sufficiently cleaned by rainwater. In many cases, especially in arid areas, or near deserts, roads, industry, or agriculture, it is cost-effective to clean photovoltaic modules regularly. In 2018, the revenue loss of photovoltaic modules caused by pollution is estimated to be between 500 and 7 billion euros.

The long-term reliability of photovoltaic modules is critical to ensuring the technical and economic viability of photovoltaics as a successful energy source. Analysis of the degradation mechanism of photovoltaic modules is the key to ensuring that the current service life exceeds 25 years.

The solar team of the manufacturer of Anhui JF Solar Technology Co., Ltd. (JF Solar) focuses on the production and development of solar photovoltaic modules with more than 12 years of experience, so there is a unique method for the shadow and dirt of photovoltaic modules. If you are right If you are interested in photovoltaic modules, please contact us. Our website is https://www.jf-solartech.com/.