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Solar photovoltaic (PV) power plant: construction under EPC contracts and project cost
Today photovoltaic power stations dominate the field of renewable energy, and PV projects and technology is rapidly changing the landscape of the global energy sector: EPC contracting and cost.
Among the reasons for investors’ interest in renewable energy sources are growing concerns about climate change, the effects of air pollution on health, the issue of energy security and affordability, as well as fluctuations in hydrocarbon prices.
Currently, the total installed capacity of PV power stations in the world exceeds 600 GW, excluding concentrating solar systems.
It is the second largest renewable energy source after wind farms.
Since the late 2010s, this technology has been a leader in the pace of construction of new power plants.
These figures are twice as much as that of wind farms.
They are even higher than those of fossil fuel plants and nuclear power plants together.
In 2020 alone, the installed PV capacity is planned to be increased by 140 GW.
According to experts from the International Renewable Energy Agency (IRENA), the development of solar energy is driven by cost savings, technological advances and the creation of the necessary associations to support the sector.
Solar photovoltaic power plant construction
Given the availability of economic and technological resources, significant market potential and competitiveness, it is expected that photovoltaic technologies will continue to lead in the field of renewable energy in most regions of the world over the next decade.
According to IRENA forecasts, the number of new solar photovoltaic stations can increase 5 times over the next 10 years, reaching a total capacity of 2840 GW by 2030 and 8500 GW by 2050.
This means that the installed PV capacity in 2050 will be 18 times more than in 2018. According to European experts, in 2050, 60% of the installed capacity will come from large-scale photovoltaic installations, and the remaining 40% from in-roof PV systems.
Although large-scale power plants will dominate in 2050, we expect faster growth in distributed PV systems, which are supported by government policies and incentives.
Asia dominates the global solar energy market today, accounting for more than half of the world’s new photovoltaic capacities.
In 2019, China added over 30 GW of installed capacity, while the European Union added 16 GW and the United States 13.3 GW.
Construction of new solar photovoltaic power stations in 2019:
| Country | New installed capacity, GW |
|---|---|
|
People’s Republic of China |
30,1 |
|
European Union (total) |
16,0 |
|
United States of America |
13,3 |
|
India |
9,9 |
|
Japan |
7,0 |
|
Vietnam |
4,8 |
|
Spain (EU) |
4,4 |
|
Germany (EU) |
3,9 |
|
Australia |
3,7 |
|
Ukraine |
3,5 |
|
South Korea |
3,1 |
Asian countries, led by China, are currently leading in the production of photovoltaic energy.
Europe is in second place and North America in third.
Projections show that Asia will continue to lead in installed PV capacity with a share of about 65% of total capacity in 2030. The most significant growth is expected in China, where the installed PV capacity will exceed 1,400 GW in 2030.
North America will take second place with 430 GW by 2030, with 90% of the facilities being built in the United States.
Europe will occupy third place with an installed capacity of about 300 GW.
In 2050, Asia will still dominate with almost half of the installed photovoltaic power in the world. According to the estimates, this figure will be 4,800 GW, of which 2,800 GW will be concentrated in China. By then, Chinese solar power will show CAGR of about 9%.
North America will retain its second position with an installed photovoltaic capacity of1720 GW.
The United States will continue to dominate the region.
Europe will retain third place with a total installed PV capacity of 890 GW in 2050. About 22% of European PV installations will be concentrated in Germany.
At the same time, market growth is likely to shift to other, less saturated markets. In the future, the rapid development of solar energy is expected in South America and Africa.
The future growth of solar energy depends largely on a balanced energy policy and a reduction in the cost of PV technology. The ways to achieve this are to use cheaper materials for solar cells, reduce the cost of manufacturing equipment and increase its efficiency.
Five countries contribute three-quarters of estimated solar capacity additions in 2024
The combined additions of China, the United States, India, Germany and Brazil are on track to make up 75% of global solar additions in 2024.
Other countries we tracked for this analysis add a further 5%. The remaining 20% are derived from analysis of Chinese solar PV exports that act as a proxy to indicate countries where significant installations may be taking place without being reported.
Innovative materials for solar PV power stations
Today, we are witnessing continuous progress in research and development for both existing and new photovoltaic technologies in order to further reduce costs and increase productivity.
Crystalline silicon (c-Si) cells are the first generation of photovoltaic cells, accounting for 95% of world production.
Due to the use of the common materials, silicon c-Si panels are more affordable and efficient than other solutions.
Over the past few decades, solar cells have improved significantly in terms of efficiency and power output. The average efficiency in 2006 was 13.2% for polycrystalline and 14.7% for single-crystal photovoltaic panels. Since then, this indicator has been growing steadily, reaching 18% and 19%, respectively.
It is expected that this positive trend will continue until at least 2030.
Currently, the strong position of c-Si in the market makes it difficult to develop other technologies. However, despite the high level of efficiency of this first-generation photovoltaic technology, there are many opportunities for improvement.
Among them:
- Lower cost of c-Si modules for higher profits
- Reduction of metal inclusions and prevention of defects
- Limiting environmental impact through waste reduction
- Obtaining finer elements due to improved material properties
PERC technology (Passivated Emitter and Rear Cell) uses an advanced silicon cell architecture. The structure of the PERC elements is slightly different from the structure of typical single-crystal cell.
The key improvement here is the integration of the surface with the passivated layer, which increases the efficiency of the cell.
The passivated layer achieves this by the recombination of electrons, increasing the absorption of light, and providing a higher internal reflectivity.
The increase in the efficiency of solar cells due to the implementation of the PERC architecture for single-crystal cells is about 0.8-1%, while the growth for polycrystalline cells is slightly lower, from 0.4 to 0.8%. PERC technology has only recently entered the global market, but is quickly becoming the new industry standard for single-crystal photocells.
Tandem solar cells are a set of individual elements located one above the other. Each of these layers converts light with a specific wavelength, allowing residual light to be absorbed and converted into electricity by the lower element.
New technologies in solar energy include several options for tandem cells, which can be grouped by the materials used (organic, inorganic, hybrid), as well as by the type of connection used.
In practice, tandem cells have been used to design the world’s most efficient solar cells, which can convert up to 50% of the energy of sunlight into electrical energy. Unfortunately, these devices use very expensive materials and production processes, so it is difficult to bring them to market.
Thin-film solar technology
Thin-film solar cells are also called second-generation photovoltaic panels.
The semiconductor materials used in the production of thin-film elements have a thickness of only a few microns.
These elements include two main varieties, including silicon-based elements (amorphous and micromorphic a-Si / c-Si) and non-silicon elements (perovskites, cadmium telluride and copper-iridium-gallium selenide, CIGS).
Thin-film solar cells can be cheaper to manufacture and easily commercialized, but their performance is still low.
Currently, most solar cells are made of silicon. But one of the areas that our engineers are focusing on is the development of new materials.
One of the most promising is perovskite, a rare mineral with a very high ability to absorb light. The first perovskite devices in 2009 converted only 3.8% of the energy of sunlight, but their efficiency is rapidly increasing.
Since crystals are very easy to make in the laboratory, their production is increasing. In 2018, the efficiency of perovskite solar cells has already reached 24.2%, which is close to the efficiency of laboratory silicon cells (26.7%).
Unfortunately, perovskite photocells still face a number of serious problems that hinder their distribution. One of them is low stability. Since perovskite crystals dissolve readily, they cannot be used in humid environments. Such elements require moisture protection by coating them with a layer of alumina or other materials.
Another problem for scientists is that the high efficiency of small perovskite solar cells is difficult to reproduce on larger systems.
If these barriers can be overcome, technology will change the economy of solar energy. Perovskite elements are much cheaper to manufacture and do not require such difficult high-temperature production conditions as silicon devices.
CIGS solar cells are also relatively highly efficient compared to crystalline silicon cells. But large-scale industrial production of CIGS elements is difficult in the short term due to the high cost of indium, complex stoichiometry and multi-stage production.
Cadmium telluride elements currently have an efficiency of more than 21%, similar to that of CIGS.
This material is characterized by rather high absorption and low energy loss.
CdTe cells are produced using low-temperature processes, which makes their production flexible and affordable. CdTe is currently the market leader among the major thin-film technologies in the solar industry.
Advanced solar PV modules
One option for double-sided modules is a glass-glass solar panel.
These are devices whose photocells are located between glass panels.
They are widely used for utilities and are considered the optimal solution for harsh and inhospitable environmental conditions (such systems are more resistant to moisture).
Despite considerable experience in the production of such panels, the high cost and significant weight of the equipment inhibits market growth. As of 2020, their market share reached 10%, but within 10 years it is expected to grow to 40%.
Semi-cells are photocells cut in half, which are produced using advanced laser machines. The development of this technology is facilitated by the simplicity of the process and minimal changes in the operation of laser machines.
Semi-cells increase the efficiency and durability of PV modules, offering an immediate increase in efficiency. Thanks to PERC integration, the semi-cell technology brings the efficiency of traditional systems to 18% or more.
Silicon solar cells are metallized in thin stripes on the side and back surfaces.
These buses are required to conduct the current generated by the cell.
Older panels usually have two buses, but the industry is moving toward higher efficiency, and the number of buses currently reaches 3, 4, or even more. A larger number of buses is associated with higher efficiency of the PV modules due to reduced losses due to internal resistance.
A brief history of solar energy
Everyone knows that photovoltaic systems convert solar energy into electricity.
However, few people know the interesting origin of the term “photovoltaic“.
The word first appears at the end of the 18th century. It consists of two parts – “photo”, derived from the Greek word “light”, and “volt” in honour of the discoverer of electricity Alessandro Volta.
The photoelectric effect was first discovered by the French physicist Edmond Becquerel back in 1839. Photovoltaic systems have long been a part of our everyday life. Today, solar power plants provide consumers with one of the most affordable and cleanest forms of energy.
After the discovery of selenium photoconductivity at the end of the 19th century, a new stage in the development of solar energy sector began. In 1941, the first selenium photocell was constructed, with an efficiency of approximately 1%.
In 1955, Western Electric Company was the first company in the world to commercialize solar panels.
Since solar radiation is much higher in space, these low-efficiency cells have been of limited use to power satellites and space stations.
In 1958, the first solar-powered satellite, Vanguard 1, was launched. Today it is considered the oldest operational satellite. It was followed in 1962 by Telstar, which was the first communications satellite to be equipped with 14W photovoltaic cells. In 1971, Soviet space stations participating in the Salyut programme were equipped with this technology.
In the 1970s, driven by the oil crisis, NASA and the US Department of Energy began developing a project to power the Earth using satellites. In 1979, a satellite fleet was proposed with an installed capacity of up to 10 GW, but in 1981 the project was closed due to the high cost of manufacturing these satellites.
The first solar photovoltaic power plants were developed in the early 1980s, and most of them were built in the United States. By the 1990s, almost all developed countries began to generate electricity using this technology, among which were Japan, Spain, Germany, Italy and others.
The important role of China in the construction of solar power plants should be emphasized. By 1997, this country had surpassed the United States to become the largest solar energy producer in the world.
Today, China is also one of the world leaders in the manufacture of equipment for solar power plants.
Using sunlight to generate electricity
Solar energy is vital to our planet. It determines the temperature of the Earth’s surface and ensures the course of numerous biological processes.
How does a photovoltaic cell convert solar energy into electricity?
To answer this question, we need to understand the properties of sunlight.
Some stars provide energy in the form of X-rays and radio signals, but the sun emits most of the energy in the form of visible light. However, visible light is only a fraction of the electromagnetic spectrum. Almost all the energy of the Sun has the wavelength from 2×10-7 to 4×10-6 meters.
Each electromagnetic wavelength has a specific frequency and energy. The shorter the wavelength, the higher the frequency and the more energy it carries. For example, red light lies at the low energy end of the visible spectrum, and violet light lies at the opposite end of the spectrum.
The same is observed in the invisible part of the electromagnetic spectrum: ultraviolet light is high energy, and infrared light is low energy. Therefore, infrared light, which we perceive as heat, carries less energy than visible light.
Photocells react differently to waves of different lengths. For example, crystalline silicon uses the visible spectrum and part of the infrared spectrum. But the amount of energy in the infrared spectrum is too little to generate electricity.
However, light containing too much energy also cannot be effectively used by photovoltaic cells to generate electricity.
The main reason is that some of this energy is converted to heat.
How powerful is solar radiation?
The sun constantly emits a colossal amount of energy.
The planet receives a tiny fraction of this energy.
For every square meter of the outer layer of the Earth’s atmosphere, there is an average of 1,360 watts of solar energy. The atmosphere absorbs and reflects some of this radiation, including most of the X-rays and ultraviolet rays. However, the amount of solar energy that reaches the earth’s surface every hour exceeds the total amount of energy that humanity uses in a whole year.
How much energy does light lose as it travels from the upper atmosphere to the Earth’s surface?
These losses depend on the thickness of the atmosphere through which the sunbeam must pass.
The energy that reaches sea level at noon in temperate latitudes with clear skies reaches 1000 W / m².
As the sun moves lower and lower in the sky, the sunbeam travels through an increasing layer of air, losing more energy. Since the Sun stays at its zenith for a short period of time, the available energy during the day is significantly less than 1000 W / m².
Features of direct and diffused light
As noted, Earth’s atmosphere and clouds absorb, reflect, and scatter some of the sunlight. However, the fraction of solar energy that reaches the Earth’s surface is sufficient to generate solar power. It should be borne in mind that part of the solar radiation is direct, and the other is scattered.
The distinction between the two types of sunlight is extremely important. Some solar power plants can use both types, however photovoltaic systems can effectively work only with direct sunlight.
Direct light includes radiation emanating directly from the Sun, which is not reflected from clouds, dust, the earth’s surface, or other objects. Experts talk about “perpendicular radiation”, meaning the portion of light that comes directly from the sun and hits the surface of a photovoltaic module at an angle of 90 degrees.
Diffuse light means the sun’s rays that are reflected by clouds, dust, the earth’s surface, or other objects. Obviously, reflected light is much more difficult to reach the module than direct sunlight. Scattered light cannot be focused by the concentrator optics.
Total solar radiation is defined as the total amount of solar energy falling on a horizontal surface. It consists of two components, direct (perpendicular) and diffuse light. It should be borne in mind that scattered and direct sunlight has different spectra.
Solar PV modules
Controllers
Inverters
Batteries
Types of solar photovoltaic power plants
Today, solar power plants can be seen in the most isolated places on Earth and in the heart of megacities.
There are different types of systems, including:
- Autonomous photovoltaic solar systems
- Solar photovoltaic power plants connected to the grid
- Solar photovoltaic power plants with a backup generator
- Hybrid PV solar systems, etc
