Solar panels mainly generate electricity by absorbing solar energy and converting them into electrical energy. Cleaning as required can ensure the cleanliness of the surface of solar panels, which helps to absorb as much sunlight as possible, thereby ensuring power generation; if the components accumulate dust for a long time, it will not only Loss of power generation, severe hot spot effect, resulting in short life and even damage to the components; therefore, it is recommended to always pay attention to the cleanliness of the components and clean them appropriately to ensure the power generation.
Therefore, we also did an experiment. The output power of the panels that were cleaned every day increased by 32% compared with the panels that were never cleaned. It can be seen that the degree of occlusion on the surface of the components still has a significant impact on the power generation. The specific impact mechanism is mainly divided into the following Three aspects cause attenuation of power generation.
1. The radiation acceptance rate decreases
The dust covering the surface of the photovoltaic panel blocks the solar radiation, resulting in a reduction in the effective area irradiated on the panel, and a decrease in the transmittance of the glass, which reduces the intensity of the solar radiation received by the panel, and will cause uneven solar radiation and power generation The amount is reduced and the output power is reduced.
Figures (a) and (b) are respectively calculated and actually measured I-V characteristic curves by changing the shadow transmittance. When a battery on the module uses different transmittances (a module is composed of 36 cells), the short-circuit current roughly changes little. The result is that the lower the transmittance, the faster the current drops with the increase in voltage. On the other hand, the open circuit voltage is basically the same.
The above figure is to study the I-V characteristics of the module by changing the number of blocked cells (the shadow transmittance is 35%). As the number of shields increases, the short-circuit current is significantly lower, but the open-circuit voltage does not change much.
2. Temperature rise
The dust covered on the photovoltaic panel reduces the transmittance through the glass plate, hinders solar radiation, and also affects the heat transfer form of the photovoltaic panel. Dust attaches to the surface of the panel to block heat transfer, which may prevent the panel's own heat from being released, making the temperature higher and higher, and affecting the efficiency of photovoltaic power generation. Most of the existing photovoltaic power plants use silicon-based solar cells, which are very sensitive to temperature. When a certain thickness of dust accumulates on the surface of the panel, it will increase its heat transfer and thermal resistance, which will keep the panel warm and reduce its heat dissipation function. Affect and even produce hot spots to damage components. Experimental results show that whenever the battery temperature rises by 1℃, its output power drops by about 0.5%.
The composition of dust is more complicated, some are acidic substances, some are alkaline substances, and the main components of crystalline silicon photovoltaic panels are silica and limestone, etc. If the dust comes into contact with the moisture in the air and becomes humid, it can be produced with the composition of the panel. Acidic or alkaline reaction. After a period of time, the surface of the photovoltaic panel will gradually undergo corrosion and damage under the erosion of an acidic or alkaline environment, making the surface pitted, causing the optical performance of the photovoltaic panel to attenuate, and the diffuse reflection of solar radiation on the surface of the panel will damage the solar radiation in the photovoltaic. The uniformity of propagation in the panel affects the amount of power generation.
Judging from the above points, the hazards of dust accumulation to the components are still very serious, and it is very necessary to clean the components regularly and in a timely manner. Related recommendations How to clean the solar panels?
Of course, not all solar panels need to be cleaned. Like many portable solar panels, they do not need to be cleaned. For example, our ITEHIL 100W 18V solar panel, ITEHIL solar panels use ETFE film, and the characteristic of ETFE is high temperature resistance. , Better light transmittance, corrosion resistance, and waterproof. Therefore, ITETHIL 100W 18V solar panel are definitely the best choice for high quality and low price.