Solar Energy: What it is, How it works, Advantages and Disadvantages

Discover how the primary form of energy that comes from the Sun’s rays actually works

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By Max Bender

Solar energy is the most important renewable energy source on the planet. Endless, 100% natural, and clean, today it plays a crucial role in the energy transition process and in combating climate change in most countries. Through the installation of photovoltaic systems and solar panels, it is increasingly being utilized worldwide.

What is Solar Energy?

Solar energy is the primary form of energy that comes from the sun’s rays, from which most other forms derive, except for geothermal energy, nuclear energy, and marine energy derived from wave motion, tides, or the temperature difference between surface and deep waters, known as ocean thermal energy.

Solar radiation can be harnessed to produce electricity. Even in nature, solar energy is utilized for its potential. Just think of plants that capture solar radiation and then convert it into energy for their growth and sustenance.

Various manuals and dictionaries define this renewable energy as the energy emitted by the Sun and transmitted to the Earth in the form of solar radiation (light and heat), which is utilized to produce energy for human purposes.

How Solar Energy Works

The Sun constantly transmits energy to the Earth in the form of solar radiation (at European latitudes, average solar irradiance is approximately 1000 watts/m2). Through a photovoltaic system, this energy is instantly converted into electrical energy in a completely sustainable manner, without the use of any moving mechanical parts, as is the case with hydroelectric power, for example, where water moves turbines, and especially without the use of fuels.

Photovoltaic systems can be standalone or grid-connected. In the latter case, direct current must be transformed using inverters.

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How Solar Energy is Produced

There are essentially 3 ways to collect solar power and then convert it into electrical energy. Let’s examine these 3 technologies in detail.

Photovoltaic Solar

Photovoltaic solar, often abbreviated as PV solar, refers to the technology that converts sunlight directly into electricity using semiconductor materials. When photons from sunlight strike these materials, they dislodge electrons, creating an electric current. This phenomenon, known as the photovoltaic effect, occurs within solar cells, the basic building blocks of photovoltaic panels. These solar cells are typically made of silicon, though other materials such as cadmium telluride or copper indium gallium selenide can also be used.

Photovoltaic solar systems consist of interconnected solar panels, which are installed on rooftops, ground-mounted structures, or integrated into building materials. The panels capture sunlight during daylight hours and generate DC (direct current) electricity, which is then converted into AC (alternating current) electricity by inverters for use in homes, businesses, and the grid.

Photovoltaic solar technology has seen significant advancements in efficiency and cost reduction over the years, making it a widely adopted renewable energy solution worldwide. Its scalability, reliability, and environmentally friendly nature have positioned photovoltaic solar as a key player in the transition towards sustainable energy systems, reducing reliance on fossil fuels and mitigating climate change.

Thermal Solar

In this case, solar radiation is used to heat water for personal hygiene purposes and to warm water for a radiator heating system in buildings.

The basic element of thermal solar is the solar collector, which intercepts sunlight and heats a fluid flowing through its tubes, transporting the heat to the intended places.

Other essential components of thermal solar are:

  • Storage tank
  • Control unit
  • Integration generator (which could be, for example, a condensing boiler or a heat pump)

Thermodynamic Solar or Concentrated Solar Power

One of the most recent technologies for collecting and using solar energy is thermodynamic solar, also known as concentrated solar power (CSP). It is a technology that utilizes sunlight to generate heat, which is then converted into electricity. Unlike photovoltaic solar panels that directly convert sunlight into electricity, CSP systems concentrate sunlight to produce high temperatures.

In CSP systems, large mirrors or lenses focus sunlight onto a receiver, which contains a heat-absorbing fluid such as oil or molten salt. As the fluid absorbs the concentrated sunlight, it heats up to very high temperatures, typically exceeding 500 degrees Celsius (932 degrees Fahrenheit).

The heated fluid is then used to generate steam, which drives a turbine connected to a generator, producing electricity. Alternatively, the heat can be stored in thermal storage systems for later use, enabling electricity generation even when sunlight is not available.

CSP technology is often used in utility-scale power plants, where large arrays of mirrors or lenses are deployed to capture sunlight and generate electricity for the grid. These systems can provide reliable and dispatchable renewable energy, making them particularly suitable for regions with high solar resource potential. Additionally, CSP plants can incorporate thermal energy storage, allowing for electricity generation beyond daylight hours and improving grid stability.

Advantages of Solar Energy

Solar power has numerous advantages. Let’s delve into them in detail.

  • Clean, free, and inexhaustible energy
  • Reduction in the use of fossil fuels, thereby reducing greenhouse gas emissions
  • Self-production even by private individuals
  • Average 90% electricity bill savings after the high costs of photovoltaic system installation have been amortized
  • Solar energy systems can provide electricity in remote areas where traditional power sources are unavailable or costly to install.
  • Minimal maintenance due to elementary photovoltaic system technology

Disadvantages of Solar Energy

Let’s see what the disadvantages of this renewable energy source are.

  • Solar radiation is not continuous due to the day/night cycle and varying weather conditions (the only option for ensuring continuous production is to install a photovoltaic system with storage)
  • Solar installations require space, hence a sufficiently large area or surface to install solar panels
  • Solar installations have significant costs, which are amortized over the years, but initially, a considerable investment must be taken into account
  • Optimal recycling and disposal of solar panels.

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Where is solar energy used?

This renewable energy is used in various applications, including:

  • Residential and commercial rooftop solar panels for electricity generation.
  • Utility-scale solar power plants that feed electricity into the grid.
  • Solar water heaters for heating water in homes, swimming pools, and industrial processes.
  • Solar-powered devices such as calculators, street lights, and remote power systems in off-grid locations.

Q&As on Solar Energy

Here are some concise answers to the most frequently asked questions on this topic.

Which Country Has the Highest Capacity for Solar Energy?

China leads the world in solar energy production by a significant margin, boasting a total capacity of 430 GW, which accounts for over 30% of the global total. Following China in terms of total solar power capacity in 2023 are the United States and then Japan.

Which Country Has the Highest Solar Energy Generation Per Capita?

The Netherlands, certainly not a country famous for sunshine, is the world leader here. In this country, solar energy generation per capita stands at 1,081.3 MW/million. The Netherlands stands out among nations advocating for green energy and ranks first among the countries with the highest solar energy generation per capita. Despite having a population of less than 18 million, the Netherlands is among the top 10 solar energy producers worldwide.

What is the future of solar energy?

The future of this renewable energy looks promising, with ongoing technological advancements driving down costs and increasing efficiency. As the world transitions to cleaner and more sustainable energy sources, solar energy is expected to play a significant role in meeting growing energy demand while reducing carbon emissions and combating climate change.

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