Discover the solar energy's potential in the global electricity supply
Learn about the current photovoltaic technologies and those in development
Design a basic photovoltaic system to meet a specific energy need at a specific location
Discover how cost-competitive solar PV is compared to other renewable and non-renewable electrical power plants
What you'll learn
Solar energy will transform electricity production in the next 10-20 years. Learn how in this engineering PDH course.
According to the Merriam-Webster dictionary, the definition of solar energy is,
"Produced or operated by the action of the sun's light or heat."
Amazingly, this simple concept has inspired dozens of engineering innovations, from passive solar building design to semi-transparent perovskite solar cells. The reason for this is the sheer abundance of energy we receive from the sun.
In this 2-hour engineering PDH course, we will answer the following questions in detail.
1. How much energy do we receive from the sun?
Here's a summary of some key points.
How much energy do we receive from the sun?
The Earth receives 174 petajoules of energy from the sun every second. Over a year, enough solar energy falls on the Earth's surface to replace all of today's global energy production. Its potential surpasses by far the combined energy output of coal, oil, natural gas, hydro, nuclear, and biofuels. Photovoltaic systems allow us to tap into this abundant resource by converting solar energy into electricity. In 2018, solar PV systems produced 2.4% of the global electricity supply, generating 505 GW worldwide and growing.
Solar PV World Electricity Production by Country
According to Eicke Weber, Director of Germany's Fraunhofer Institute for Solar Energy Systems,
Between 2030 and 2050, we will see 10-30% of global energy demand covered by solar PV (photovoltaics). Right now, we are in an embryonic state compared to where we are going in a few decades.
In this course, we will provide an overview of the use of solar energy for electricity production, specifically with solar photovoltaic technologies (also known as solar PV).
How does a photovoltaic solar cell produce electricity?
The solar cell is made of a semiconductor, usually silicon that has been "doped" with an agent that has the propensity to either gain or lose electrons. Examples of doping agents are phosphorus and boron.
Phosphorous-doped silicon can lose electrons and is known as an N-type semiconductor. Since an N-type semiconductor wants to lose electrons, it acquires a positive charge.
On the other hand, boron-doped silicon has a shortage of electrons, or an abundance of "holes," and is known as a P-type semiconductor. Since P-type silicon wants to lose holes and gain electrons, it acquires a negative charge.
Joining these two types of silicon forms a PN junction, the foundation of the solar cell.
The PN Junction of a Solar Cell
Source: Physics Stack exchange
An internal electric field (E) forms at the junction. The force of the electric prevents the free charges found in the P-type and N-type silicon from recombining.
When a photon hits the solar cell, it gives its energy to an electron in the crystal lattice. This energy excites an electron from the P-type silicon and "kicks" it into the conduction band, where it is free to move around within the semiconductor. The difference in energy between the valence band and the conduction band is known as the bandgap.
When the electron leaves the P-type silicon, it leaves its place empty, creating a "hole." An electron from neighbouring atom moves into the "hole," leaving another hole behind.
In this way, holes propagate throughout the crystal lattice. As this happens, electricity begins to flow in the circuit. This phenomenon is known as the photovoltaic effect.
Ideally, a photon with an energy equal to that of the bandgap hits the solar cell and excites an electron from the valence band to the conduction band.
Note that different materials have different bandgap energies, as shown in this table.
Bandgap Energies of Various Semiconductors
Most solar panels today are made of silicon solar cells. However, most photons hitting the Earth have greater energies than the bandgap of silicon. The solar cell still absorbs these high-energy photons, but their "extra energy" is converted into heat rather than electricity. When this happens, the efficiency of the solar cell decreases.
What different types of cells exist today?
How efficient are solar cells at converting solar energy into electricity?
Researchers are continually working to improve the efficiency of solar cells. Each new wave of solar cells gives rise to a new generation of photovoltaic devices.
Today, there exist three generations. They are,
- Crystalline Silicon (Monocrystalline and polycrystalline solar cells)
- Thin film
- Emerging PV
Commercially available mono and multi-crystalline silicon solar cells have efficiencies of around 18-23%.
Second-generation solar cells, or thin-film solar cells, include amorphous, cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS) solar cells. In the lab, both CIGS and CdTe have achieved cell efficiencies of 18% while the efficiency of amorphous-Si is only 13%.
The third generation of solar cells includes several thin-film technologies often described as "emerging photovoltaics." Most third-generation solar cells have yet to be commercialized and are still in the research and development phase. Today, the efficiency of this type of solar cell is about 10%.
Solar Cell Efficiencies
Source: IRENA Letting in the Light
An example of emerging photovoltaics is the Perovskite solar cell. It is based on low-cost materials and shows much promise in terms of efficiency and cost.
Perovskite solar cell efficiency under laboratory conditions has improved dramatically, increasing from 14% to 22% in recent years.
Here is a picture of a perovskite solar module printed by inkjet on a flexible substrate. An external LED shows that the module can generate power under scattered light conditions.
Perovskite Solar Module
Source: Saule Technologies
How much does solar power cost?
When analyzing the cost of any utility, investors look at the "Levelized Cost of Energy" (LCOE). The LCOE is the ratio between the lifetime cost of the energy utility and its energy production. In short, the LCOE is the price the project must earn per megawatt-hour to break even.
This figure shows the range of LCOE for PV projects from 2010 to 2017, taking into account variations in the costs and sizes of individual projects. Between 2010 and 2017, the global weighted average LCOE fell 72%, from 0.36 USD/kWh to 0.10 USD/kWh (360 USD /MWh to 100 USD/MWh).
Cost of Solar PV Has Dropped 72% between 2010 - 2017
The projected reduction in installation costs could result in an average 59% decrease in LCOE of commercial-scale PV projects between 2015 and 2025. By 2025, the global weighted average LCOE could be as low as 0.03 USD/kWh (30 USD/MWh).
How does the cost of solar power plants compare to other electricity-producing technologies?
According to IRENA's 2018 report, "Renewable Power Generation Costs in 2017", solar PV utility-scale plant costs are comparable with other renewable sources of energy as well as fossil fuel-fired plants.
This figure shows the global weighted average LCOE of each technology, excluding any subsidies.
Average LCOE of Solar PV is Comparable to Fossil-Fuel Fired Power Plants
Notice that in 2017, the global average LCOE of solar was well within the range of fossil fuel-fired power plants for many regions around the world, as shown in this figure. It shows the regional average LCOE of each technology and excludes any subsidies. In Asia, Oceania, North America, and Europe, the regional average LCOE falls within the range of fossil-fuel-fired power plants based on 2017 data. The LCOE of solar ranges from 9.5 cents US per kWh in Asia to a high of 17 cents US per kWh in Africa and Eurasia.
What are the disadvantages of solar energy?
Different electricity sources also have different environmental costs. Today, the world is focused on carbon emissions and greenhouse gases (GHGs), often presented in tonnes of CO2 equivalent. Solar power plants generation emissions, whereas other types of generation can produce substantially more.
However, reliability is a significant concern, as system operators are mandated to ensure supply meets demand at all times. Intermittent sources of power, such as wind and solar, must be backed up by other sources of generation. Which brings us to the topic of an upcoming course - energy storage. But first, we invite you to preview the first video of this engineering PDH course below.
Video Lesson Sample
Excellent! Very instructive. Well made. Bravo!
It was really helpful to understand solar energy in terms of efficiency and cost.
Very interesting and relevant topic! I thoroughly enjoyed learning about the subject.
Solar Energy Online Course Welcome! (1 min 15 sec)FREE PREVIEW
Course ContentFREE PREVIEW
How to take this courseFREE PREVIEW
Helpful HintFREE PREVIEW
Download the Complete Course NotesFREE PREVIEW
Download the Quiz (25 multiple choice questions)
Solar Energy and the Global Electricity Supply (3 min 46 sec)FREE PREVIEW
Could the world run on solar power? (3 min 01 sec)FREE PREVIEW
How much land is needed to run the world on solar power? (8 min 23 sec)FREE PREVIEW
What Would It Take To Power The United States With Solar Energy? (1 min 04 sec)FREE PREVIEW
Practise QuizFREE PREVIEW
How does a solar cell produce electricity? (3 min 54 sec)
What is the photovoltaic effect? (4 min 34 sec)
How do solar panels work? (4 min 58 sec)
How is the efficiency of a solar cell measured? (4 min 45 sec)
How to calculate how many solar modules you need (11 min 16 sec)
How efficient are solar cells today? (7 min 04 sec)
What is the maximum possible efficiency of a solar cell? (6 min 20 sec)
Take a 360 degree tour of MBR Solar Park in Dubai (2 min 36 sec)
Solar power: the next generation (4 min 00 sec)
How much does a solar power plant cost? (9 min 12 sec)
Here's Why Solar Energy May Beat Out Coal in a Decade (3 min 38 sec)
The Cost Decline of Solar Power (5 min 49 sec)
Solar Energy in a Nutshell (7 min 48 sec)
PV Solar Power Cheat Sheet
Largest solar power plant in the world, 2017 (1 min 08 sec)
Solar and wind cheaper than fossil fuels (1 min 27 sec)
What is the Duck Curve? (2 min 43 sec)
Tesla reveals the future of the power grid (9 min 53 sec)
60% of our energy will come from renewable zero emission sources by 2040 (1 min 15 sec)
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The Complete PV Solar Power Course Bundle (5h)
Could the planet be powered solely by the sun? How big a role does solar energy play in the global energy mix today? Will the sun be a major source of power in the future? How green is this technology? Find out in this course bundle on PV solar power
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