Solar Energy: Definition, Types, & How Does It Work?

What is Solar Energy?

Solar energy is radiant light and heat from the Sun that is harnessed using a range of ever-evolving technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture, molten salt power plants, and artificial photosynthesis.

Solar energy comes from the sun and can be captured with various technologies, primarily solar panels. The “photovoltaic effect” is the mechanism by which silicon solar panels harness the sun’s energy and generate electricity.

Solar energy is the cleanest and most abundant renewable energy source available, and the U.S. has some of the richest solar resources in the world. Solar technologies can harness this energy for a variety of uses, including generating electricity, providing light or a comfortable interior environment, and heating water for domestic, commercial, or industrial use.

How Does Solar Energy Work?

Solar technologies convert sunlight into electrical energy either through photovoltaic (PV) panels or through mirrors that concentrate solar radiation. This energy can be used to generate electricity or be stored in batteries or thermal storage.

Solar power works by converting light from the sun into electricity. This electricity can then be used in your home or exported to the grid when it’s not needed. This is then fed into a solar inverter which converts the DC electricity from your solar panels into AC (Alternating Current) electricity.

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  • Your solar panels consist of silicon photovoltaic cells. When sunlight hits your solar panels, the solar cells absorb the sun’s rays and electricity is generated via the photovoltaic effect. The power produced by your panels is known as direct current and is not suitable for use in your home by your devices. Instead, the direct current is sent to your central inverter.
  • Your inverter can convert the direct current to an alternating current that can be used in your home. From here the alternating current is fed to your switchboard.
  • A switchboard can send your usable AC power to the devices in your home. Your switchboard always ensures that your solar energy is used to power your home first and only then accesses additional energy from the grid when your solar production is insufficient.
  • All households with solar energy must have a bidirectional meter that your electricity dealer will install for you. A bidirectional meter can record all the electricity that is drawn from the house, but also the amount of solar energy that is exported back into the grid. This is known as a network measurement.
  • Unused solar power is then fed back into the grid. If you export solar energy back into the grid, you will receive a credit on your electricity bill, which is known as the feed in tariff. Your electricity bills then take into account the electricity that you get from the grid, as well as credits for the electricity that is generated by your solar system and that you do not use.

With solar energy, you don’t have to turn it on in the morning or at night the system does this seamlessly and automatically. There is also no need to switch between solar and grid power as your solar system can determine when it is best to use the amount of energy used in your home.

In fact, a solar system requires very little maintenance, which means you hardly ever know it is there. This also means that a good quality solar system has a long lifespan.

Solar Technologies

There are three ways to use solar energy: photovoltaics, solar heating and cooling, and concentration of solar energy. Photovoltaics generate electricity directly from sunlight through an electronic process and can be used to power everything from small electronic devices like calculators and traffic signs to households and large commercial operations.

Solar heating and cooling (SHC) and concentrating solar energy (CSP) applications both use the heat generated by the sun to provide space or water heating in SHC systems or to run conventional power generation turbines in CSP power plants.

Types of solar Energy

Photovoltaic technology directly converts sunlight into electricity. Solar thermal technology harnesses its heat. These different technologies both tap the Sun’s energy, locally and in large-scale solar farms.

Two major technologies have been developed to harness it:

  • Photovoltaic solar technology, which directly converts sunlight into electricity using panels made of semiconductor cells.
  • Solar thermal technology, which captures the sun’s heat. This heat is used directly or converted into mechanical energy and in turn electricity, known as concentrated solar power. This heat is used directly (low‑temperature solar thermal) or converted into mechanical energy and in turn electricity (concentrated solar power – CSP).

1. Photovoltaic Solar Power

The photovoltaic effect (or photoelectric effect) converts light into electricity. It was discovered by the French physicist Edmond Becquerel in 1839 and first used in industrial applications in 1954. The principle: an electric current is created when electrons are displaced. To do this, photons (light particles) stimulate the outermost electrons of the atoms of certain semiconductor elements.

In practice, light that hits a photovoltaic cell is converted into electricity by a semiconductor, generally silicon. A photovoltaic module consists of several cells that generate direct current, which is then converted into alternating current by an inverter. Panels can be used in small systems or large plants.

Photovoltaic Technology

2. Solar Thermal

Solar thermal is a well proven technology delivering energy and carbon savings. A solar thermal system works by harnessing is the sun’s energy and converting it into heat which is then transferred into your home or businesses heating system as hot water or space heating.

Solar thermal panels are used in conjunction with a boiler, collector, or immersion heater. The solar collector will use the sun’s rays to heat a transfer fluid which is a mixture of water and glycol, to prevent the water from freezing in the winter. The heated water from the collectors is pumped to a heat exchanger inside a water cylinder. The heat from the exchanger will then heat the water inside the cylinder.

After the liquid releases its heat, the water will flow back to the collectors for reheating. A controller will ensure that the fluid will circulate to the collector when there is sufficient heat available. Solar thermal technology is proven, reliable and low maintenance.

Solar Thermal Technology

3. Concentrated Solar Power

This second type of thermal solar energy technology concentrates the heat of the sun’s rays with the help of collectors in order to heat a transmission fluid (e.g. gas, oil or molten salt) to a high temperature. The liquid heats a network of water that creates steam and drives a turbine (mechanical energy), which generates electricity.

The heat from the sun’s rays is collected in large power plants in which flat or curved mirrors are installed over large areas. The technology is best suited to countries where sunlight is intense, such as desert regions.

4. Solar power plants

The Solar power plant that we can use the solar energy of the sun for energy commonly used in industrial applications. As we all know that most power plants use non-renewable fossil fuels to boil water.

The steam from boiling water rotates a large turbine which in turn activates the generator to produce electricity. This method of generating electricity is bad for both the environment and our health as the burning of fossil fuels emits greenhouse gases and air pollutants.

However, the good news is that a new generation of power plants is being launch which relies on solar Energy.

These plants use the sun as a heat source, and they can do this in three different ways:

  • Parabolic-trough systems capture the sun’s energy throughout long rectangular, curved mirrors that tip toward the sun. In this way, they help to concentrate sunlight on a pipe that contains oil. Oil is heated and used and used to boil water in a conventional steam generator to generate electricity.
  • A dish/engine system uses a mirrored dish the size of a very large satellite dish that receives and focuses the sun’s heat on a receiver. This receiver consumes heat and transfers it to the fluid within an engine. The heat causes the fluid to circulate against the piston or turbine and produces mechanical strength. This electricity is used to run a generator or alternator to generate electricity.
  • A power tower system uses a large area of mirrors to focus sunlight on top of a tower, where a receiver containing molten salt sits. Salt heat is used to generate electricity through conventional steam generators. The molten salt efficiently retains heat, so it can be stored for days before being converted into electricity. This means that electricity can be produced even on cloudy days or several hours after sunset.

5. Solar Water Heating System

The idea behind the Solar water system comes directly from nature: the shallow water of a lake or the water at the shallow end of a beach is generally warmer than deep water. This is because sunlight can heat the lake or seafloor in shallow areas, which in turn heats the water.

Therefore, a system has been developing to mimic this: the solar water heating system for buildings compose of two parts, a solar collector and a storage tank.

The most common collector is calling a flat-plate collector mount on the roof and facing the sun. Small tubes run through the box and carry fluid – either water or other liquids, such as an anti freezer solution – to heat. As the heat increases in the collector, it heats the fluid passing through the tubes. The storage tank then contains the hot liquid.

A similar technique is often use to heat swimming pools.

6. Passive Solar Heating

Another method that solar energy can be used is through passive solar heating and the daylight method. This is not a new concept – in fact, ancient civilizations such as the Anasazi Indians in Colorado developed the passive solar design in their habitats.

It is easy to understand the effect of the sun: step outside on a hot sunny day and you can feel the sun. With a decent design, buildings can also “feel” the sun’s energy.

For example, south-facing windows will receive more sunlight, while buildings can also contain the heat and absorbing materials of the sun, such as sun floors and walls.

These materials heat up during the day and gradually release heat at night when the heat is most needed. Other design features, such as a sunspace that resembles a greenhouse, concentrate too much heat that can use to heat an entire building with the right ventilation. Such features maximize the direct benefit from the sun’s heat, but also the sunlight itself. The even better news is that especially on hot days, there are ways to ensure that these facilities do not overheat buildings.

Pros and Cons of Solar Energy

Advantages of Solar Energy

1. Renewable Energy Source

Among all the advantages of solar panels, the most important one is that solar energy is a truly renewable energy source. It can be used in all regions of the world and is available daily. Unlike some other energy sources, we cannot run out of solar energy.

Solar energy will be available as long as we have the sun, so sunlight will be available to us for at least 5 billion years when scientists say the sun dies.

2. Reduces Electricity Bills

Since you cover part of your energy needs with the electricity generated by your solar system, your energy costs go down. How much you save on your bill depends on the size of the solar system and your electricity or heat consumption.

For example, if you are a company that uses commercial solar panels, this switch can have huge benefits as the large system size can cover large chunks of your energy bills.

In addition, not only do you save electricity but there is also the option of receiving payments for the excess energy that you export back into the grid via the Smart Export Guarantee (SEG). When you generate more electricity than you use (considering that your solar panel system is connected to the grid).

3. Diverse Applications

Solar energy can be used for various purposes. They can generate electricity (photovoltaics) or heat (solar thermal energy). Solar energy can be used to generate electricity in areas with no grid access, to distill water in regions with limited supplies of clean water, and to power satellites in space.

Solar energy can also be incorporated into the materials used for buildings. Not so long ago, Sharp introduced solar transparent windows.

4. Low Maintenance Costs

Solar systems generally do not require a lot of maintenance. You just need to keep them relatively clean, so cleaning them a couple of times a year is enough. When in doubt, you can always count on specialist cleaning companies to offer this service between £ 25 and £ 35. The most reliable manufacturers of solar modules offer a guarantee of 20 to 25 years.

Since there are no moving parts, there is also no wear and tear. The inverter is usually the only part that needs to be replaced after 5-10 years, as it works continuously to convert solar energy into electricity and heat (solar PV vs. solar thermal). In addition to the inverter, the cables also need to be maintained to ensure that your solar system is running at maximum efficiency.

After you cover the initial costs of the solar system, you can expect very little maintenance and repairs.

5. Technology Development

Technology in the solar industry is constantly evolving and improvements will intensify in the future. Innovations in quantum physics and nanotechnology can potentially increase the effectiveness of solar panels and double or even triple the electrical input of solar power systems.

Disadvantages of Solar Energy

1. Cost

The initial cost of buying a solar system is quite high. This includes paying for solar panels, inverters, batteries, wiring and installation. Nevertheless, solar technologies are constantly evolving, so it can be assumed that prices will fall in the future.

2. Weather-Dependent

Although solar energy can still be collected on cloudy and rainy days, the efficiency of the solar system decreases. Solar panels rely on sunlight to effectively collect solar energy. As a result, a few cloudy, rainy days can have a noticeable impact on the energy system. You should also take into account that solar energy cannot be collected at night.

However, if you also want your water heating solution to work at night or in winter, thermodynamic panels are an alternative.

3. Solar Energy Storage Is Expensive

Solar energy must be used immediately or can be stored in large batteries. These batteries, which are used in off-grid solar systems, can be charged during the day so that the energy is used at night. This is a good solution for using solar energy all day, but it’s also quite expensive.

In most cases it is wiser to only use solar energy during the day and take energy from the grid at night (this is only possible if your system is connected to the grid). Fortunately, your energy needs are usually higher during the day, so you can get most of it from solar energy.

4. Uses a Lot of Space

The more electricity you want to produce, the more solar panels you will need to collect as much sunlight as possible. Solar panels take up a lot of space and some roofs are not big enough to accommodate the number of solar panels that you would like.

An alternative is to install some of the panels in your yard, but they must have access to sunlight. If you don’t have enough space for all of the panels you want, you can install fewer to meet some of your energy needs.

5. Associated with Pollution

Although the pollution from solar energy systems is far less compared to other energy sources, solar energy can be associated with pollution. Transportation and installation of solar systems have been linked to greenhouse gas emissions.

There are also some toxic materials and dangerous products that are used during the manufacturing process of photovoltaic solar panels that can indirectly affect the environment.


What is solar energy?

Solar energy is radiant light and heat from the Sun that is harnessed using a range of ever-evolving technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture, molten salt power plants, and artificial photosynthesis.

What is solar energy definition?

Solar energy is radiant light and heat from the Sun that is harnessed using a range of ever-evolving technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture, molten salt power plants, and artificial photosynthesis.

How does solar energy work?

Solar technologies convert sunlight into electrical energy either through photovoltaic (PV) panels or through mirrors that concentrate solar radiation. This energy can be used to generate electricity or be stored in batteries or thermal storage.

Who invented solar energy?

In 1839, French physicist Edmond Becquerel discovered the photovoltaic effect while experimenting with a cell made of metal electrodes in a conducting solution. He noted that the cell produced more electricity when it was exposed to light.

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