Photovoltaic power generation is the process of directly converting light energy into electricity by using the photovoltaic effect generated at the semiconductor interface. The DC energy generated by the generator is converted into AC energy through an inverter, which is then boosted and transmitted to the power grid through a booster transformer station, and the electricity is transmitted to the consumer side through the grid transmission line.
Photovoltaic power plants are mainly divided into two categories: centralized power plants and distributed power plants. Because of the high flexibility of PV power plant installation compared to wind power, compared to traditional large-scale wind power plants, PV power plants can not only be installed centrally on a large scale, but can also be distributed on the surface of buildings, outdoors and many other scenarios.
Centralized photovoltaic power plant is the PV array installed in the mountains, water, desert and other wide areas, sunlight photovoltaic array can produce DC electricity, inverter and then DC electricity into AC electricity, through the booster station to connect to the grid. The scale of centralized photovoltaic power plants is generally larger, generally above 10MW, and the number of very large photovoltaic power plants above 100MW is gradually increasing.
Distributed photovoltaic power plants generally have a small installed capacity and are more flexible in installation. Distributed power plants can be mainly divided into two categories: those combined with buildings and those not combined with buildings, and those combined with buildings can be divided into building integrated photovoltaic (BAPV) and building integrated photovoltaic (BIPV).
Under the background of carbon peak and carbon neutral, PV power generation is developing rapidly as the backbone of China's energy transformation, and its main advantages include.
(1) Green and environmental protection. PV power generation itself does not consume fuel, does not emit anything including greenhouse gases and other exhaust gases, does not pollute the air and does not produce noise.
(2) Improving national energy stability. Through photovoltaic power generation, people can reduce their dependence on fossil fuel power generation and effectively avoid shocks caused by energy crises or unstable fuel markets, thus improving national energy security.
(3) Extensiveness. The sun's rays irradiate the earth's surface and are not limited to any geographical area, whether on land, sea, mountains or flatlands, and can be exploited. Although the irradiation time and intensity vary, they are widely distributed and will not be inaccessible due to geographical or weather reasons.
(4) Infinity and sustainability. Based on the current rate of nuclear energy generated by the sun, it is estimated that there is enough hydrogen in storage to last for tens of billions of years. In today's increasingly serious ecological pollution, solar energy resources are inexhaustible, a truly renewable and clean energy.
(5) Low operation and maintenance costs. Photovoltaic power generation has no mechanical transmission parts, and is stable and reliable. A set of photovoltaic power generation system as long as there are solar modules can generate electricity, coupled with the extensive use of automatic control technology, basically unattended, low maintenance costs.
(6) Flexible installation location. The roof of a building is open, and has the advantages of not being affected by the orientation of the building, receiving light for a long time, and avoiding shadow interference to the greatest extent. Photovoltaic power generation can be installed not only on the roofs of residential facilities, but also in industrial-scale facilities to obtain electricity through solar power generation to meet the electricity demand in buildings. In the field of rural revitalization, the development of rooftop distributed photovoltaic technology can also effectively solve the problem of electricity consumption in county areas.
At the same time, there is no denying that there are some disadvantages of PV power generation at this stage, and better development of the industry in the future should focus on overcoming these disadvantages. The main disadvantages are manifested in.
(1) Wide footprint. Due to the small energy distribution density of sunlight irradiation, this leads to the large-scale application of photovoltaic power generation, the equipment covers a large area relative to other power generation equipment.
(2) Unstable energy supply. Photovoltaic power generation is affected by seasonal changes, weather conditions, alternating day and night, and the intensity of solar radiation. Long-term rainy and snowy days, cloudy days and even changes in cloud cover can affect PV power generation, and when there is no sun it cannot generate electricity or the amount of electricity generated is very small, which can affect the normal use of electricity-using equipment.
(3) Strong geographical dependence. Due to different geographical locations and different climates, sunlight resources vary greatly from region to region. Some areas rich in light energy resources are far away from the load center of electricity consumption, and the local economy is underdeveloped, so the ability to consume is weak, which requires long-distance centralized transmission through the transmission grid, resulting in the inevitable loss of energy generated by photovoltaic power generation.