Before we start, let's look at a piece of news:
This news comes from Inner Mongolia, China. A large number of photovoltaic module arrays in a local photovoltaic power station were crushed or damaged by heavy snow, resulting in heavy losses.
Here are some pictures of the scene after the snow:
According to people familiar with the matter, the photovoltaic power plant project has an installed capacity of 60 megawatts, and it is initially estimated that up to 80 to 90 percent of the photovoltaic module arrays have collapsed or been damaged.
European countries often snow in winter, and heavy snow warnings are often issued. Partners with photovoltaic power plants at home need to take precautions in advance to avoid the tragic situation of the previous news.
To take precautions, you need to know three things:
One: The load capacity of photovoltaic modules:
The maximum allowable surface pressure is in Pascals, 6000 Pascals. This means that the surface of the PV modules can withstand a maximum load of 6,000 Newtons per square meter. One kilogram of snow results in a weight of 9.81 Newtons. Divide the maximum pressure in Pascals by 10 to get the maximum allowable snow load per square meter in kilograms.
Two: How much snow is:
Snow changes its weight over time. This happens through the absorption of moisture on the one hand and the compression of the snow by its own weight on the other. The dry snow that has just fallen does not pose a threat to PV modules, and one meter of snow depth is equivalent to a load of about 50 to 60 kilograms per square meter. When the snow gets wet and thick, things change dramatically. In these cases, the weight may increase by a factor of about ten.
Three: The relationship between snow thickness and load
1 square meter * 10 cm = 25㎏
1 square meter * 20 cm = 50㎏
1 square meter * 30 cm = 75㎏
100 square meters * 30 cm = 7.5 tons
At present, the design load of steel structure factory roof is generally within the range of 30~50㎏.
After knowing the three knowledge points, you can calculate the maximum weight of snow that your photovoltaic power station can bear. How to prevent the snow accumulation of photovoltaic power station from reaching the maximum bearing weight?
Four: How to prevent snow in the early stage
In winter, PV modules are easy to accumulate dust and snow, and the power loss of PV modules by dust and snow is more than 5%. Cleaning of PV modules can avoid the hot spot effect and prolong the service life of PV modules.
For areas in Europe where it often snows, it is recommended to install photovoltaic modules with a larger inclination angle, as the snow will slide off to a certain extent, reducing the accumulation speed of snow. When installing, keep a certain distance between the bottom of the photovoltaic module and the ground, and the snow will fall off and accumulate on the bottom, so that it will not accumulate on the photovoltaic module later.
Five: How to clear snow
If there is heavy snow on the PV modules after snow, it needs to be cleaned. You can use soft objects to push the snow down, and be careful not to scratch the glass. Photovoltaic modules have a certain load-bearing capacity, but they cannot be stepped on to clean them, which will cause cracks or damage to the photovoltaic modules and affect the life of the photovoltaic modules. It is generally recommended not to wait until the snow is too thick before cleaning, so as to avoid freezing of photovoltaic modules.
In many cases, the reflection of snow contributes a small amount to photovoltaic power generation. If the snow does not cover the PV modules, the snow on the ground will act as a mirror to send sunlight back, so that the power generation will increase. However, if the snow cover completely covers the photovoltaic modules, and only a small part of the sunlight passes through the snow and irradiates the photovoltaic modules, it will affect the photovoltaic power generation.
Six: Precautions for cleaning snow
Be sure to pay attention to the use of soft items to prevent scratching the glass and reduce the light transmittance of solar cell modules;
Be sure not to wash the solar panel surface with hot water, as the unevenness of cold and heat will seriously damage the solar panel surface;
Be careful not to step on the photovoltaic modules for cleaning. The photovoltaic modules have certain load-bearing requirements, which may cause cracks or damage to the photovoltaic modules and affect the life of the photovoltaic modules.
Be careful not to wait until the snow is too thick before cleaning, so that the photovoltaic modules will not freeze.
Snow removal must be clean, do not underestimate the snow strips. If there is only a small piece of snow on the solar panel, it should be cleaned up. The blocked solar panel will fail as a whole, and the power generation efficiency of the inverter will be significantly reduced.
Seven: The way to clear the snow
1. Mop snow removal
Use a soft cloth mop to push the snow down. This method of snow removal saves money and trouble.
But be careful: do not use sharp objects, so as not to scratch the glass
2. Cover with cloth or plastic bag
Small photovoltaic power stations can also be covered with cloth or plastic bags when it snows, and they can be uncovered when the snow stops.
3. Robotic snow removal
Large-scale photovoltaic power stations can use robots to remove snow. Reminder: When cleaning snow for photovoltaic power plants, pay attention to safety, especially when standing on the roof.