1. Introduction to solar photovoltaic power generation Photovoltaic power
generation is a power generation method that uses the photovoltaic effect to
convert solar radiation energy into electrical energy. It is the mainstream of
solar power generation today. Solar power generation is the generation of
electricity that directly converts light energy into electrical energy without
going through a thermal process... Keywords: solar photovoltaic, photovoltaic
power generation system, electrical energy.
1. Introduction to solar photovoltaic power generation
Photovoltaic power generation is a power generation method that uses the
photovoltaic effect to convert solar radiation energy into electrical energy. It
is the mainstream of solar power generation today. Solar power generation is a
power generation method that directly converts light energy into electrical
energy without going through a thermal process. It includes photovoltaic power
generation, photochemical power generation, light induction power generation and
photobiological power generation.
2. Categories of solar photovoltaic power generation systems
Solar power generation systems can be divided into two major categories,
one is an independent system, and the other is a system-connected system (also
known as a system connected to the AC grid). The independent system is the most
basic form of solar power generation system, also known as the prototype system
of solar power generation. This kind of system is mostly used as a power supply
for offshore lighthouses, buoys, wireless relay stations on mountaintops, etc.
that are far away from urban areas (unmanned operation). The DC power output by
the solar array is directly supplied to the load. If the load is AC, the DC
power must also be converted into AC power through an inverter. In addition, the
output DC energy also supplies electricity storage
battery charging. Since the voltage of the load often fluctuates, a
controller should also be set up to regulate the voltage. In power system terms,
it is called countercurrent operation or colloquially known as selling
electricity. On the contrary, for the power company, normal operation is to
provide power to users, which is called positive power flow. The advantage of
the system-connected solar power generation system is that when the solar power
generation is insufficient in rainy weather or at night, power can be purchased
directly from the mains power grid through the system connection. Another
important advantage of the system connection system is that the battery can be
eliminated, which reduces the cost and enhances the stability and reliability of
the power supply.
3. Power generation method of solar photovoltaic power generation
system
Solar power generation methods There are two ways of solar power
generation, one is the light-heat-electricity conversion method, and the other
is the light-electricity direct conversion method.
3.1. Light-heat-electricity conversion method
By utilizing the thermal energy generated by solar radiation to generate
electricity, a solar collector generally converts the absorbed thermal energy
into steam as a working fluid, and then drives a steam turbine to generate
electricity. The former process is a light-to-heat conversion process; the
latter process is a heat-to-electricity conversion process, which is the same as
ordinary thermal power generation.
3.2. Direct light-to-electricity conversion method
This method uses the photoelectric effect to directly convert solar
radiation energy into electrical energy. The basic device for photo-electric
conversion is the solar cell. A solar cell is a device that directly converts
sunlight energy into electrical energy due to the photovoltaic effect. It is a
semiconductor photodiode. When the sun shines on the photodiode, the photodiode
converts the sun's light energy into electrical energy, producing current. When
many batteries are connected in series or parallel, a solar cell array with
relatively large output power can be formed.
4. Main factors affecting solar photovoltaic power generation
The utilization of solar energy mainly utilizes the solar radiation
reaching the ground. Solar radiation can be divided into two types. One is the
optical radiation emitted from the surface of the photosphere. Because it
spreads light and heat in the form of electromagnetic waves, it is also called
electromagnetic wave radiation. This radiation consists of visible light and
invisible light. The other is particulate radiation, which is a particle flow
composed of positively charged protons and roughly equal amounts of negatively
charged electrons and other particles. Particulate radiation is usually weak and
the energy is unstable. During the maximum period of solar activity, The most
intense, it has a certain impact on humans and the earth's upper atmosphere, but
generally speaking, it gradually disappears on the long journey between the sun
and the earth before it radiates to the earth's surface. For this purpose solar
radiation is mainly optical radiation. Due to the existence of the atmosphere,
the amount of solar radiation that actually reaches the earth's surface is
affected by many factors. Generally speaking, the main factors are solar
altitude, atmospheric quality, atmospheric transparency, geographical latitude,
sunshine time and altitude.
5. Composition of grid-connected solar photovoltaic power generation
system
The photovoltaic system consists of the following three parts: solar cell
components; power electronic equipment such as charge and discharge controllers,
inverters, test instruments and computer monitoring, and batteries or other
energy storage and auxiliary power generation equipment. (As shown in Figure
1).
Figure 1 Photovoltaic grid-connected system structure diagram
Photovoltaic systems have the following characteristics:
(1) There are no rotating parts and no noise is generated;
(2) No air pollution or waste water discharge;
(3) There is no combustion process and no fuel is required;
(4) Simple maintenance and low maintenance costs;
Photovoltaic systems are widely used. The basic forms of photovoltaic
system applications can be divided into two categories: independent power
generation systems and grid-connected power generation systems. The main
application fields are mainly in space special equipment, communication systems,
microwave relay stations, TV differential turntables, photovoltaic water pumps
and household power supply in areas without electricity.
6. Development and Prospects
Since the 1990s, my country's photovoltaic power generation has developed
rapidly. During this period, my country's photovoltaic module production
capacity increased year by year, costs continued to decrease, the market
continued to expand, and installed capacity increased year by year. In 2006, the
cumulative installed capacity reached 35MW, accounting for approximately 3% of
the world's share. For more than 10 years, my country's photovoltaic industry
has maintained a long-term average It maintains a share of about 1% of the
global market. By 2020, my country's photovoltaic technology industry will
continue to be improved and developed, costs will continue to drop, and the
photovoltaic market will undergo tremendous changes: It is expected that from
2005 to 2010, my country's solar cells will mainly be used in independent
photovoltaic power generation systems to generate electricity. The cost will be
approximately 1.20 yuan/kWh by 2010;
From 2010 to 2020, photovoltaic power generation will shift from an
independent system to a grid-connected power generation system, and the power
generation cost will be approximately 0.60 yuan/kWh by 2020. By 2020, the
technical level of my country's photovoltaic industry is expected to reach the
world's advanced ranks. At present, the world's solar photovoltaic power
generation industry is still in its infancy. In order to ensure the healthy
development of the solar photovoltaic power generation industry, the following
work needs to be done:
(1) Develop a maximum power tracking algorithm for solar photovoltaic cells
to achieve maximum power tracking of sunlight;
(2) Develop an optimal combination algorithm for solar photovoltaic arrays
to achieve optimal combination of solar photovoltaic cell arrays;
As the world's energy consumption continues to rise, environmental
pollution caused by the abuse of fossil energy is becoming increasingly serious.
While dealing with sustainable economic development, humans must also focus on
the issue of ecological balance. Humanity will be more active in exploring and
researching the use of solar energy, which also indicates that solar
photovoltaic grid-connected power generation will play an increasingly important
role in future society.
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