Overview and application of solar photovoltaic power generation

1. Introduction to solar photovoltaic power generation

Solar photovoltaic power generation is a power generation method that uses the photovoltaic effect of solar cells (a semiconductor device similar to a crystalline diode) to directly convert the sun’s radiant energy into electrical energy. The energy converter of solar photovoltaic power generation is a solar cell, also called PV. When sunlight hits the solar cell (consisting of two different types of homogeneous semiconductor materials of P and N type), part of the light is reflected, part of the light is absorbed, and part of the light passes through the cell. The absorbed light can excite the bound electrons in the high-energy state to generate electron-hole pairs. Under the action of the built-in electric field of the PN junction, the electrons and holes move with each other (as shown in Figure 1). The holes move to the P area, and the electrons in the P area move to the N area, so that a large amount of negative charges (electrons) accumulate on the light-receiving surface of the solar cell, and a large amount of positive charges (holes) accumulate on the backlight surface of the battery. If a load is connected to both ends of the battery, current will flow through the load. When the light keeps shining on, there will be a continuous flow of current through the load. A monolithic solar cell is a thin semiconductor PN junction. Under standard light conditions, the rated output voltage is 0.5~0.55V. In order to obtain higher output voltage and larger power capacity, multiple solar cells are often used in practical applications. The batteries are connected together to form a battery module, or more battery modules are used to form a photovoltaic array, as shown in Figure 2. The output power of the solar battery is random, and the output power of the same solar battery is also different under different time, different locations, different light intensity, and different installation methods.

Overview and application of solar photovoltaic power generation
Figure 1 – Principle of solar photovoltaic cell power generation
Overview and application of solar photovoltaic power generation
Figure 2 – From cell, cell module to photovoltaic array

2. Application of solar photovoltaic power generation

Solar cells and photovoltaic power generation systems have been gradually applied to industry, agriculture, science and technology, national defense, and the daily lives of ordinary people. It is expected that by the middle of the 21st century, solar photovoltaic power generation will become one of the main forms of power generation, occupying a certain amount of renewable energy structure. Proportion. The specific applications of solar photovoltaic power generation mainly include the following aspects.

(1) Applications in the communication field: including solar unattended microwave relay stations (as shown in Figure 3), optical cable communication systems and maintenance stations, mobile communication base stations, broadcasting and communication power systems, satellite communication and satellite TV receiving systems, and rural program control Telephone, carrier telephone photovoltaic system, small communication machine, etc.

Figure 3 – Solar Microwave Relay Station

(2) Applications in highway, railway, and shipping transportation: such as railway and highway signal systems, railway signal lights, traffic warning lights, sign lights, signal lights, road solar street lights, solar road stud lights, high-altitude obstacle lights, highway monitoring systems, Highway and railway wireless telephone booths, unattended road crews power supply, navigation beacon light beacon and navigation beacon light power supply, etc. An example of the application of solar lamps is shown in Figure 4.

Figure 4 – Application of solar lamps

(3) Applications in the fields of petroleum, ocean and meteorology: solar power systems for cathodic protection of petroleum pipelines and reservoir gates, life and emergency power supplies for oil rigs, marine testing equipment, meteorological and hydrological observation equipment, observation stations, power supply systems, etc. .

(4) Application in rural and remote areas without electricity: solar off-grid photovoltaic power generation systems, villages, schools, hospitals, restaurants, hostels, shops, etc., applied in rural areas and remote areas without electricity such as plateaus, islands, pastoral areas, border posts Small wind and solar hybrid power generation system. Solar photovoltaic water pumps to solve power problems such as deep-water well drinking and farmland irrigation in areas without electricity. There are also applications such as solar sprayers, solar electric fences, and solar black light insect killers (as shown in Figure 5).

Figure 5 – Rural solar photovoltaic power station and solar pest killing lamp

(5) Application of solar photovoltaic lighting: solar street lights, garden lights, lawn lights, solar landscape lighting, solar road signs, signal indicators, advertising light box lighting, etc., as well as household lighting (as shown in Figure 6) and portable lamps , Camping lights, climbing lights, fishing lights, tapping lights, energy-saving lights, flashlights, etc.

Figure 6 – Solar small desk lamp

(6) Application of large-scale ground-based photovoltaic power generation system (power station): Mainly used in the central and western regions of China with good sunlight resources and a large amount of non-agricultural land.

(7) Application of distributed photovoltaic power generation and building-integrated photovoltaic power generation system (BIPV): use industrial and commercial roofs, public facility roofs and family residential roofs to install distributed photovoltaic power generation systems, and use solar cell modules to replace building materials and serve as buildings The use of roofs and facades of buildings enables various buildings to realize the grid-connected operation of photovoltaic power generation systems and power grids, mainly for self-generation and self-use, and the surplus power is sent to the grid (as shown in Figure 7). This will be the current situation. And the main form and development direction of photovoltaic power generation applications for a period of time in the future.

Figure 7 – Solar photovoltaic building integration

(8) Application of solar products and toys: solar radios, solar clocks, sun hats, solar mobile phone chargers, solar watches, solar calculators, solar toys, etc., as shown in Figure 8.

Figure 8 – Solar cell phone charger and solar toy

(9) Applications in other fields: solar electric vehicles, electric bicycles, solar yachts, solar charging equipment, solar car air conditioners, ventilators, cold drink boxes, etc., as well as regenerative power generation systems for solar hydrogen production and fuel cells, and power supply for seawater desalination equipment. Satellites, spacecraft, space solar power plants, etc., as shown in Figure 9.

Figure 9 – Space applications of solar cells