Solar energy is a renewable and clean energy source that is increasingly being noticed and utilized. Solar panel is a device that converts solar energy into electricity, which is widely used in various occasions, such as home, business, industry, agriculture, transportation and so on. In this article, we will introduce the basic principles of solar panels, power generation efficiency, influencing factors, storage methods, etc. to help better use and maintain solar panels.

 

What is the photovoltaic effect?

The photovoltaic effect is the phenomenon of generating a voltage or current when light strikes a semiconductor material. A solar panel is a device that utilizes the photovoltaic effect to convert the energy of sunlight into electricity. A solar panel consists of multiple solar cells, each consisting of two layers of different types of semiconductor material, one layer being N-type and the other P-type. When sunlight shines on a solar cell, photons (particles of light) excite electrons, which flow from the N-type layer to the P-type layer, forming an electric current. This is the basic principle of the photovoltaic effect.

 

How do solar panels generate electricity?

The process of generating electricity from solar panels can be divided into three steps:

 

The first step is that the solar panel converts the energy from sunlight into direct current. This step is realized using the photovoltaic effect, as described above.

 

The second step is to convert the direct current into alternating current. This step requires the use of a device called an inverter. The function of the inverter is to adjust the voltage and frequency of the DC power to AC power that matches the grid for transmission and use. The inverter is usually installed near the solar panels or in the meter box.

 

The third step is to deliver the AC power to the grid or to the user. This step requires electrical equipment such as wires, switches, and protectors to ensure the safety and stability of the electricity. If the solar panel generates more electricity than the user uses, the excess can be delivered to the grid and sold to the power company, or stored for future use.

 

How much energy can be generated at one time?

The amount of power generated by a solar panel depends on several factors, the main ones being the following:

 

• The area and efficiency of the solar panel. The larger the area, the more efficient it is and the more electricity it generates. The efficiency of a solar panel refers to the percentage of the solar cell that converts the sun's energy into electricity, which is generally between 15% and 25%, and varies between different types and brands of solar panels. The area of the solar panel can be determined according to the user's electricity needs and installation space, usually in square meters.

 

• Intensity and duration of sunlight. The higher the intensity and the longer the duration, the more electricity is generated. The intensity of solar light is affected by geographic location, season, climate, weather and other factors, and is generally measured in watts per square meter. The time of sunlight refers to the length of time the solar panel receives sunlight, generally measured in hours. The amount of electricity generated by a solar panel can be estimated using the following formula:

 

Electricity generation (kWh) = area of the solar panel (square meters) x efficiency of the solar panel (%) x intensity of the sunlight (watts/square meter) x duration of the sunlight (hours)

 

• Angle and orientation of the solar panel. The more appropriate the angle and the more positive the orientation, the more electricity will be generated. The angle of the solar panel refers to the angle between the solar panel and the horizontal plane, which should generally be similar to the local latitude to ensure that the solar panel receives the most sunlight during the year. The orientation of the solar panel refers to the front face of the solar panel, which should generally face due south (northern hemisphere) or due north (southern hemisphere) to ensure that the solar panel receives the most sunlight during the day. If the angle and orientation of the solar panel is not appropriate, it will result in the solar panel being less efficient in generating electricity.

 

How to improve the efficiency of solar energy conversion?

There are several ways to improve solar panel conversion efficiency:

 

• Choose an efficient solar panel. Different types and brands of solar panels have different efficiencies. Generally speaking, the efficiency of crystalline silicon solar panels is higher than that of amorphous silicon solar panels, and monocrystalline silicon solar panels have the highest efficiency of more than 25%. Of course, efficient solar panels will be correspondingly more expensive, so users need to choose the right solar panel according to their budget and needs.

 

• Install a tracking system. A tracking system is a device that automatically adjusts the angle and direction of a solar panel so that it always faces the sun. Tracking systems can be categorized into single-axis tracking, which can only adjust the horizontal angle of the solar panel, and dual-axis tracking, which can adjust both the horizontal and vertical angles of the solar panel. Tracking systems can significantly improve the power generation efficiency of solar panels, but they can also increase the installation cost and maintenance difficulty of solar panels.

 

• Clean solar panels. Dust, dirt, snow, bird droppings, etc. on the surface of solar panels can block sunlight and reduce the power generation efficiency of solar panels. Therefore, users should clean the solar panel regularly to keep its surface clean and smooth. There are several ways to clean solar panels:

 

• Wipe the surface of the solar panel with a soft cloth or sponge to remove dust and dirt. Be careful not to use hard objects or harsh detergents that may scratch or corrode the solar panel.

 

 

• Rinse the solar panel surface with water to remove snow and bird droppings. Be careful not to use hot water or a high-pressure water gun as this may damage the solar panel.

 

• Deep clean and inspect solar panels regularly with professional cleaning tools or services. This will detect and repair any damage or deterioration of the solar panels and increase the life and efficiency of the solar panels.

 

Does weather have an effect on solar panels?

The effect of solar panel power generation is affected by the weather in the following ways:

 

• Cloudy weather. When it is cloudy, the intensity of sunlight decreases, resulting in less power being generated by solar panels. However, solar panels can still utilize the scattered sunlight to generate electricity, it will just be less efficient. Typically, solar panels are about 50% less efficient at generating electricity when it's cloudy.

 

• During the winter, the duration of sunlight is shortened, resulting in a reduction in the amount of electricity generated by solar panels. However, the angle of the sunlight decreases in winter, resulting in an increase in the receiving area of the solar panel, which increases the power generation efficiency of the solar panel. In addition, the temperature of solar panels decreases in winter, which also helps to increase the efficiency of solar panels. In general, the power generation efficiency of solar panels increases by about 10% during winter.

 

• Rainy days. When it rains, the intensity of sunlight decreases dramatically, resulting in almost zero power generation from solar panels. However, when it rains, the surface of the solar panel is rinsed with water, which removes dust and dirt and improves the cleanliness and efficiency of the solar panel. Generally, the efficiency of solar panels in generating electricity is reduced by about 90% during rainy days.

 

• Snowy days. On snowy days, the intensity of sunlight decreases, resulting in less power generation from solar panels. However, on snowy days, the sunlight is reflected by the snow, increasing the amount of light received by the solar panel, thereby increasing the solar panel's power generation efficiency. In addition, the temperature of the solar panel decreases during snowy days, which also helps to increase the power generation efficiency of the solar panel. Generally speaking, the power generation efficiency of solar panels increases by about 20% during snowy days.

 

Where does the unused electricity go?

The amount of electricity generated by the solar panel and the amount of electricity used by the user are not always equal, and sometimes there is excess or shortage. In this case, there are several ways to deal with it:

 

• Grid-connected system. Grid-connected system is a system in which solar panels are connected to the power grid, allowing for a two-way flow of electricity. When the solar panel's power generation exceeds the user's electricity consumption, the excess power can be delivered to the grid and sold to the power company for revenue. When the amount of electricity generated by the solar panels is less than the user's electricity consumption, the user can purchase electricity from the grid to supplement the shortfall. The advantage of a grid-connected system is that it saves electricity, reduces electricity bills, and improves economic efficiency. The disadvantage of a grid-connected system is that it requires the installation of equipment such as inverters, meters, and switches, which increases installation costs and maintenance difficulties. In addition, grid-connected systems are also affected by the stability of the grid and policies, and sometimes there are power cuts or restrictions.

 

• Off-grid system. An off-grid system is a system in which solar panels are isolated from the grid and only supply electricity for the user's own use. When the solar panel's power generation exceeds the user's electricity consumption, the excess power can be stored in batteries for later use. When the amount of electricity generated by the solar panels is less than the user's electricity consumption, the user can take out the electricity from the battery to supplement the shortfall. The advantage of an off-grid system is that it can be independent of the grid, free from outside interference, ensuring the safety and stability of the electricity. The disadvantage of off-grid systems is that they require the installation of batteries, controllers and other equipment, which increases installation costs and maintenance difficulties. In addition, off-grid systems are also limited by the capacity and life of the batteries, which can sometimes result in insufficient or wasted power.

 

• Hybrid system. A hybrid system is a system in which solar panels are connected to both the grid and the battery, allowing for multiple flows of electricity. When the solar panels generate more power than the user's electricity consumption, the excess power can be delivered to the grid, stored in the battery, or both, depending on the user's choice. When the amount of electricity generated by the solar panels is less than the amount of electricity used by the user, the user can, at the user's option, purchase electricity from the grid, take it out of the battery, or both. The advantage of a hybrid system is that the flow of electricity can be flexibly regulated to maximize the use of electricity and increase its efficiency. The disadvantage of hybrid systems is that they require the installation of equipment such as inverters, meters, switches, batteries, and controllers, which increases installation costs and maintenance. Also, hybrid systems are affected by both the grid and the batteries, which can sometimes lead to complications.

 

Conclusion

Solar panel is a device that utilizes solar energy to generate electricity, which has the advantages of being clean, renewable, economical and environmentally friendly. The power generation and efficiency of solar panels are affected by a variety of factors. Users should choose the right solar panel for their situation, install it at the right angle and direction, use the right treatment, and clean and maintain the solar panels on a regular basis to ensure proper operation and optimal performance of the solar panels.