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Photovoltaic power plants are energy systems that are affected by environmental factors and the power generated varies during operation due to environmental factors. Project location, installation direction and tilt angle affect the power generation of the power plant.
Therefore, we need to choose well the site where the photovoltaic power plant will be installed. Regarding how to choose, the project needs specific analysis and design due to various factors such as site selection, installation direction and tilt angle.
Project site selection
Take the fixed installation, the fixed installation is influenced by the latitude and longitude of various regions. As latitude increases from high to low, the optimal tilt angle changes.
Compared to the total radiation in the horizontal plane, the total radiation in the oblique plane is higher in high-latitude regions.
Conclusions: For the same total horizontal radiation, greater power generation in higher latitude regions can be greatly increased by using different installation angles in different seasons;
In low latitude regions, using different installation angles in different seasons does not cause much variation in power generation.
Installation Direction
It is usually installed directly to the south and the angle of inclination of the installation is usually equal to the local longitude and latitude or varies by a few degrees.
As a result of the tests, optimal fixed tilt installations increased radiation by 17% to 30% compared to the monitoring systems, while the dual-axis monitoring system increased radiation by 35% to 43%.
Inclination angle
The tilt angle should closely follow the installation direction and be adjusted according to the seasons. After all, the sun angle is different in different seasons.
In order to maximize the power generation efficiency, it is also necessary that the PV modules can capture the sun and collect energy, and the tilt angle should be adjusted in a timely and effective manner.
Furthermore, factors affecting system efficiency such as line loss, component efficiency and maintenance level should also be considered, which will affect the overall power generation efficiency of the photovoltaic system.
By improving our understanding, we hope to help you solve your questions about photovoltaic power generation.
During the production and transportation of photovoltaic modules, no matter how careful one is, cracks and damages cannot be avoided. These cracks and damages are caused by irregular surface stresses caused by external forces during welding or transportation.
When there is a rapid increase in temperature in a low temperature environment over a short period of time without preheating, a temperature difference occurs between the inner and outer surface and this expansion leads to cracks. Sometimes the instantaneous high temperature during welding can also cause cracks.
The following measures can be taken to prevent the formation of these hidden cracks in photovoltaic modules:
Photovoltaic module cracking is a common problem and the challenge is to prevent cracks as much as possible, reduce the probability of cracking and improve the quality of the manufacturing process of modules.
Since the renewable energy sector, especially the solar energy sector, is still very new, people still have many questions about photovoltaic modules. One of them is“Do solar panels always need direct sunlight?”.
A quick answer would be “No, it doesn’t need it”. In this article we will talk about the relationship between the energy production of photovoltaic modules and the sun and weather.
When the sunlight hits the PV module at a 90° angle, the PV module produces maximum energy. Positioning and angle are therefore very important for solar devices. In the northern hemisphere, solar panels should be oriented to the south to produce the most energy. The tilt of the PV modules will give efficient results at values close to the latitude of the project location.
But photovoltaic modules do not need direct sunlight to work. Even if it is overcast and covered by dark clouds, photovoltaic modules still generate energy.
As the sun emits radiation at different wavelengths, in addition to the rays visible to the human eye, it also contains invisible rays. These invisible rays pass directly through the clouds and enter the photovoltaic module. As long as it is daytime, photovoltaic modules continue to generate energy. Therefore, photovoltaic modules will continue to produce energy even when they are not in direct sunlight.
However, in the case of continuous shade, both the lifespan of PV modules is shortened and energy production can drop by up to 75%.
They usually divide the modules into three or four sections. If the cell in one section is blocked, the diode does not affect the other sections. For example, in a 330W photovoltaic module, if one solar cell is blocked, the four-diode solar cell loses only 25% of its power. A three-diode solar panel loses a third of its output.
If the modules are connected in series and a series inverter is used, the PV module under shade can become a problem. The poor performance of one panel will negatively affect the power production of the other panels. To avoid this situation, you can use a microinverter or combine the series inverter with the power optimizer of each panel.
On cloudy days, the performance of solar panels is reduced by 10-25%. However, in cities and towns that do not have enough sunlight, it can still make sense to utilize solar energy because the profitability of solar photovoltaic systems depends on the price of electricity: the higher the price of electricity, the shorter the payback period of the solar investment.
With technological advances in solar systems in recent years, efficiency can be as high as 95% even when it is cloudy. A good energy conversion rate in cloudy conditions can quickly recover the cost of your solar panels, even in places where it may not seem like a good idea.
Photovoltaic modules are very thin systems. The materials used must be subjected to detailed inspections after a careful production line process to avoid human or machine-induced damage.
The materials of solar cells often show dark spots and fracture problems at the corners and edges.
Broken corners often occur at the edges and corners of the solar cell panel, often related to damage from collisions. Often, incoming materials enter the production process without being checked or verified, resulting in defective products and production losses.
The process to be carried out for corner and edge collapse is to strictly screen the incoming materials and send them back to the manufacturer when defects are detected.
Dark films and broken gratings are usually caused by raw materials. Dark films cause internal damage, leading to confusion in the power range. Broken gratings can occur during the production or transportation process.
We should not underestimate problems such as dark films and broken grids. It is important not to mix power levels during the production process, especially when replacing single cells.
It is also important to strengthen the inspection of incoming materials, increase the sampling rate and timely notify the supplier of any problems detected.
Dust and bird droppings adhering to the surfaces of solar panels in the outdoor environment for a long time reduce the efficiency of the solar panel.
We should perform periodic maintenance on solar panels so that our energy production efficiency does not decrease.
Although the materials of construction of photovoltaic power generation systems vary, all solar modules contain several layers of materials, from the surface to the backlighting surface. Sunlight first passes through a protective layer (usually glass) and then enters the solar cell through a transparent contact layer.
At the center of the solar module is the absorbing material that absorbs photons and completes the “photo-generated current”. Among them, semiconductor materials vary depending on the specific photovoltaic system requirements, and photovoltaic modules are mostly composed of seven main materials.
1. Aluminum alloy frame
Protects glass edges; Aluminum alloy is combined with silicone clamping, improving the sealing performance of solar modules; Greatly improves the overall mechanical durability of solar modules, Facilitates the installation and transportation of solar modules,
The connection carrier, which carries and supports the solar modules, ensures optimal load-bearing capacity from unit fixing to integration, improving the mechanical capacity of the power plant system.
2. Tempered glass
Low iron tempered suede glass (also known as white glass) has a transmittance of more than 93% for the solar cell spectral response (in the wavelength range 320-1100 nm) and has a high reflectivity for infrared light greater than 1200 nm.
This glass is also resistant to solar ultraviolet radiation and its transmittance is not reduced.
The glass must be clean and free from water vapor. The two surfaces of the glass should not come into contact with bare hands. It usually has functions such as supporting the structure of photovoltaic modules, improving the load-bearing and durability of photovoltaic modules, transparency, anti-reflex transparency, water resistance, gas resistance and anti-corrosion.
3. EVA packaging adhesive film
It is a hot melt adhesive, a copolymer of ethylene and vinyl acetate. It is used to encapsulate solar cells, prevent the external environment from affecting the electrical performance of solar cells, increase the transparency of photovoltaic modules, and bond solar cells, tempered glass and backplanes together, and has a certain adhesion strength.
It also has a gain effect on the electrical performance output of the photovoltaic module.
4. Photovoltaic welding strip
Also known as tinned copper strip, it is basically divided into interconnection strip and bar strip. Interconnecting strips are used in the connection between solar cells, acting to conduct electricity and collect current from the solar cells.
The bar strip is used to connect the solar cell arrays of the components, combining the current generated by the solar cells and transferring it to the junction box.
5. Solar cells
Solar cells are devices that convert direct light energy into electrical energy. They are made of semiconductor materials. By illuminating with sunlight, electron-holes pairs are excited and the dissociation of electron-holes pairs is realized using the electrostatic field in the P-N bonding region.
The separated electrons and holes are collected outside through the electrode and form a current.
6. Back panel
The backshield is used as the packaging material, the most common types include TPX, KPX and PET, and improves the aging and corrosion resistance of photovoltaic modules and prolongs the service life; the white backplane improves the light absorption efficiency of the PV module by diffusing the light entering into the PV module.
It also has high infrared emissivity, so it can reduce the operating temperature of the PV module; it also improves the insulation performance of photovoltaic modules.
7. Connection box
It is a box installed on photovoltaic modules, which has the function of current conduction and has good electrical performance. At the same time, the design and size of the junction box should meet the requirements of the use environment, such as electrical, mechanical, heat resistance, corrosion resistance and weather resistance. At the same time, it should not cause harm to users and the environment.