With the development of society, the utilization of solar energy can basically be divided into several major categories: light-to-heat conversion, light-to-electricity conversion, light-to-biological conversion, and light-to-chemical conversion. For example, the solar water heaters we use at home are products that utilize light-to-heat conversion. In modern society, electricity can be regarded as the cornerstone of human civilization. If we can generate electricity using solar energy that is inexhaustible and renewable, our society will become cleaner and more efficient.
The principle of photovoltaic power generation
When it comes to solar power generation, the first thing that comes to mind is photovoltaic power generation. Under the sunlight, the electricity generated by the solar panels is charged into the battery or directly supplied to the electrical appliances. This type of power generation is called photovoltaic power generation. In this process, the solar panels play a core role, serving as the hub for converting solar energy into electricity.
Photovoltaic working principle diagram
How do solar panels work? This brings us to the topic of the photoelectric effect. In 1887, German physicist Hertz conducted an experiment and discovered that if the electrode receiving electromagnetic waves was exposed to ultraviolet light, spark discharge became more likely to occur. In 1905, Einstein proposed the concept of “photons” and successfully explained the effect where metals emit electrons under the irradiation of light. In 1941, Bell Laboratories successfully produced the first single-crystal silicon solar cell and it has continuously evolved, developing into the current solar panels.
Solar panels are devices that respond to light with photoelectric effects and can convert light energy into electrical energy. Most of them are made of silicon materials. Under the illumination of sunlight, some photons are absorbed by the silicon materials in the solar panels. The energy of the photons is transferred to the silicon atoms, causing the electrons orbiting around the silicon nucleus to undergo a transition and become free electrons. These free electrons gather at different positions, like building a dam, forming a potential difference. If there is a connection between the two, the electrons, like water, flow from a higher position to a lower position, forming a circuit of current, successfully converting the energy in sunlight into electrical energy.
However, the voltage generated by a single solar panel in this situation is simply too low to meet our daily life needs. On this basis, scientists discovered that if a series of solar panels are connected in series and encapsulated to form a large-area solar cell module, and then combined with components such as power controllers, a photovoltaic power generation device that can meet our needs can be formed.
Nowadays, solar power generation can be seen everywhere around us. In some places, solar panels are installed on the rooftops, which are used for generating electricity or for lighting purposes, or to supply power to the grid. Solar street lights use solar energy to charge the batteries during the day, and at night, the batteries supply power to the lamps, allowing the lamps to provide us with bright lighting. Most of the signals we need for watching TV are transmitted by satellites, and the main source of energy for the satellites in space is the solar panels on them. Some places also have photovoltaic parking shelters, which combine solar power generation with the car shelters, providing power for electric vehicles and reducing the electricity pressure on cities.