Photovoltaic power station dust monitoring system

1. Product overview of dust monitoring system for photovoltaic power stations

Photovoltaic power station dust monitoring system is also known as photovoltaic module battery board dust detector, photovoltaic power station dust online monitoring system, photovoltaic power station dust monitoring system measures and calculates dust loss index and dust accumulation rate, the operation and maintenance personnel of the power station according to the dust given by the monitoring system The coefficients are cleaned accordingly.

Contaminants on the glass of solar modules are one of the main problems quickly affecting photovoltaic power plants, reducing power generation efficiency and cost-effectiveness. Dust pollution will greatly reduce the power generation of photovoltaic power plants, which is estimated to be at least 5% per year. Using optical closed-loop measurement of blue light pollutants (OMBP) technology, it can be easily installed into new or existing photovoltaic arrays and integrated into the power plant management system. The unit is mounted on a frame of photovoltaic panels. The reduction in sunlight reaching the solar modules is calculated by continuously measuring the transmission loss due to contamination on the glass.

By measuring the ratio (SR) of pollutants, it is converted into a loss of power generation in real time. This lets operations and maintenance personnel know when contamination has reached a critical point and it has become necessary to begin cleaning procedures. The product requires no maintenance, just wash it in the same way you wash surrounding components.

Because large-scale photovoltaic power plants have different pollution rates throughout the park, multi-point measurements are required in the IEC 61724-1 standard. Compared with traditional systems, the cost of acquisition, installation and maintenance is much lower, which makes it more economical, so cleaning can be planned when and where it is needed.

2. The impact of dust on photovoltaic power generation

We all know that dust covers the components, forming a shielding phenomenon, which directly leads to a decrease in the power output of the components, and the long-term adhesion of dust has a certain corrosion effect on the components. At the same time, the constant presence of dust will cause hot spots on the components, further reducing the output power of the components, and even affecting the life of the components. And the hot spot effect is irreversible for components. Once there is no way to make up for it, the only option is to replace the component. Otherwise, it will affect the power generation, and may also bring potential safety hazards to the power station.

A number of research institutions at home and abroad have conducted research on the effect of dust on the power attenuation of photovoltaic systems, and the data obtained are shown in Figure 1.

It can be seen from the above figure that the output power of my country's photovoltaic system is affected by dust by about 20% on average.

The impact of dust on photovoltaic power generation is mainly attributed to the following three aspects:

1. Temperature influence

At present, photovoltaic power plants mostly use silicon-based solar cell components, which are very sensitive to temperature. With the accumulation of dust on the surface of the components, the heat transfer resistance of the photovoltaic components is increased, and it becomes the heat insulation layer on the photovoltaic components, affecting its heat dissipation. .

Studies have shown that the temperature of solar cells increases by 1°C, and the output power decreases by about 0.5%. And when the battery module is exposed to sunlight for a long time, the covered part heats up much faster than the uncovered part, resulting in dark spots of burnt out when the temperature is too high.

Under normal illumination conditions, the covered part of the battery panel will change from a power generation unit to a power consumption unit, and the covered photovoltaic cell will become a load resistor that does not generate power, consuming the power generated by the connected battery, that is, heat, which is the hot spot effect. This process will aggravate the aging of the battery board, reduce the output, and cause the components to burn out in severe cases.

2. Occlusion effect

Dust adheres to the surface of the battery panel, which will block, absorb and reflect the light, the most important of which is the light blocking effect. The reflection, absorption and shielding effect of dust particles on light affect the absorption of light by photovoltaic panels, thereby affecting the efficiency of photovoltaic power generation.

Some studies have pointed out that dust deposited on the light-receiving surface of the battery panel will firstly reduce the light transmittance of the panel surface; secondly, it will change the incident angle of some light, resulting in uneven transmission of light in the glass cover.

Studies have shown that under the same conditions, the output power of a clean battery panel module is at least 5% higher than that of a dusty module, and the higher the amount of dust, the greater the decline in module output performance.

3. Corrosion effect

The surface of photovoltaic panels is mostly made of glass, and the main components of glass are silica and limestone. When wet acidic or alkaline dust is attached to the surface of the glass cover, the components of the glass cover can react with acid or alkali.

As the time of the glass in the acidic or alkaline environment increases, the glass surface will be slowly eroded, resulting in pits and depressions on the surface, resulting in diffuse reflection of light on the surface of the cover plate, and the uniformity of transmission in the glass will be destroyed. , The rougher the cover plate of the photovoltaic module, the smaller the energy of the refracted light, and the energy actually reaching the surface of the photovoltaic cell decreases, resulting in a decrease in the power generation of the photovoltaic cell. And rough, sticky surfaces with adhesive residue are more likely to accumulate dust than smoother surfaces. Moreover, the dust itself will also absorb dust. Once the initial dust exists, it will lead to more dust accumulation, which will accelerate the attenuation of the power generation of photovoltaic cells.

3. Product Features of Photovoltaic Power Plant Dust Monitoring System

1. Real-time data monitoring: four types of data can be collected and analyzed: pollution ratio, cleanliness ratio, dust thickness, and backplane temperature. Dual probes are used for pollution ratio and cleanliness ratio

The average data calculation mode ensures accurate and reliable data.

2. Scientific and technological collector: The dust environment data collector adopts a new generation of 32-bit MCU processor, and integrates high-precision 4G and Bluetooth digital chips on board, so that the collected data can be sent to the data monitoring platform through wired or wireless methods.

3. Innovative blue light technology: adopts a new generation of blue light pollutant optical closed-loop measurement (OMBP) technology, which can effectively ensure high-precision dust data detection, and effectively prevent sunlight from interfering with closed-loop optical path collection data. It can be used for a long time under all-weather conditions, which is better than the requirement in the "IEC 61724-1 Standard" that it can only monitor effectively for three hours at 11-13 o'clock every day.

4. Smart power station cleaning: built-in a new generation of Internet of Things management and control module, with four control modes: normally open and normally closed, cycle control, time control, and manual control. According to the set pollution threshold and control mode, it can be linked with cleaning robots or IoT management and control equipment to automatically clean the dust on the battery panels to ensure the high-efficiency power generation needs of photovoltaic power plants.

5. Accuracy self-calibration: There is a one-key accuracy self-calibration button integrated on the device. According to different application environments and different use times, the acquisition accuracy of the device will decrease. The blue light monitoring circuit can be automatically recalibrated through the self-calibration button to ensure accurate and reliable data observation.

6. Green power supply management: The data acquisition instrument can adopt two power supply modes of AC220V and DC12V. And a new generation of green power management module is integrated inside to realize the intelligent switching of AC and DC power supply.

4. Technical indicators of dust monitoring system for photovoltaic power stations