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Solar energy

From a sign of deity to Einstein’s object of study: since the dawn of mankind, sunlight has defined its evolution. We’ve learned to respect it, study it and lastly, harness it, in order to secure a brighter future for us all, in every way.

About solar energy

The mother of all energy

If the earth is our home, we owe a lot to solar energy. Just to offer some perspective, solar radiation is the key element of chlorophyll photosynthesis which kickstarts the basis for life for most creatures that inhabit the planet. Sunlight also accounts for winds, tides and fossil fuels, hence, the Sun is the real driving force behind all energy sources on our planet.

Over the centuries, humankind leveraged the strong connection linking plant life and the sun, especially to learn how to manage the lifecycle of plants to transform them in edible crops. As technological progress plowed on, by the end of the nineteenth century it allowed to transform the sun’s energy in electricity through the solar cell: a device that leverages the physics phenomenon known as the photovoltaic effect.

Today, after nearly 150 years since the onset of the first photovoltaic cell, solar energy is the fastest growing renewable energy source (+24% yearly, according to the 2019 IRENA report) and its technological development follows through, delivering ever more efficient solar power plants. The global threshold of 500 GW-worth of installed capacity is ready to be reached and surpassed, with Asia leading the global growth trend. Hence, the sun will keep on shining and guiding the unstoppable rise of green energy. 

The history of solar energy

A future bound energy, from fire to electricity.

The Sun God

Since ancient times, the Sun is recognized as a source of life, so much so that some populations consider it as a deity. Hindu scriptures define the sun as “one who nourishes”. For Greek philosophy Plato, it embodied the image of good.

Olympia’s fire

Proof of solar energy emerged in the tales of Ancient Greece. Some artistic depictions show how during the first sporting events, the Olympic flame stemmed from a lens that focused the solar heat on the tip of a baton. A similar method was used to create bonfires during festivals and religious rituals.

A brilliant weapon

According to legend, Archimedes used a system of reflecting mirrors to converge the sun rays towards a specific point, coinciding with the sails of Roman vessels besieging Syracuse during the second punic war. The sails bursting to flames were testament to the sun’s incredible power!

An imperial harvest

Romans introduce glass in dwellings as a way to increase luminosity and retain warmth. Ancient Rome’s spas were the empire’s to-go leisure centers and benefited much from large south-facing glassed openings. Around 37 AD the first glass greenhouse is built in order to grow vegetables that were served to Emperor Tiberius.

The discovery of refraction

The Arab polymath Ibn Al-Haythnam in his “Book of Optics” is the first to explain how the refraction of light works and why a sphere of transparent material focuses solar radiation in a point located underneath the very same sphere. His work would have great influence on Francis Bacon and other European philosophers. 

Leonardo’s mirror

Leonardo da Vinci designs a parabolic mirror capable of harnessing solar energy to dry sheets of cloth. In his work “De distillatione”, the philosopher and alchemist Giovanni Battista Della Porta describes the workings of a solar-powered seawater distiller.

The first solar collector

The Swiss scientist and climber Horace de Saussurre is credited with the invention of the first solar collector. With a wooden pot covered in black cork and three layers of glass, he manages to capture the sun’s heat and boil water for cooking purposes.

From platinum to electricity

French physicist Edmond Becquerel notices how some platinum rods - when hit by sun rays - generate a small electrical current. It’s known as the photoelectric effect and its the underlying phenomenon of today’s photovoltaic cells.

Selenium’s turning point

British electrical engineer Willoughby Smith discovers that selenium if exposed to light, improves its electric conductivity.

The first solar cell

US scientist Charles Fritts manufactures the first solar cells made from a layer of selenium and a gold foil. Their conversion rate was lower than 1% but they opened the gate for a widespread use of solar energy as an energy source.

Up on NY’s sun-kissed roofs

The first solar panel was mounted on a New York roof. Its performance was well below acceptable levels so its production was abandoned.

Einstein, photons, and electrons

Albert Einstein is awarded the Physics Nobel Prize for its groundbreaking work that led to his formulation of the photoelectric effect, neatly explaining how light interacts with electricity. The scientist theorized that light is made by photons containing energy, which in turn set in motion electrons from some materials like selenium. 

Silica, the beginning of a new era

Chapin, Filler, and Pearson develop a silica-based solar cell, converting solar energy in electricity, thus serving as a power source for everyday appliances. The New York Times hailed this invention as “the start of a new era that will finally lead to harness limitless energy of the sun to benefit humankind”. 

Sun and space

Silica cells feature on the US-built Vanguard I, the first solar-powered satellite. This leads the way for solar energy to become an integral part of satellites, powering the space-orbiting infrastructure that delivers news, movies, weather information, phone communications and much more to contemporary society. 

From factories to roads

The first photovoltaic cells hit the market, albeit at a prohibitive price. This is until Elliot Berman managed to engineer solar cells with a lower production cost, allowing their implementation on emergency lights, lighthouses and railway crossings.

Renewables soar

The first global oil shock caused widespread disruption and the resulting crisis paved the way for a run on renewable energy sources

Swiss efficiency

Markus Real installed 3 kW solar arrays on 333 rooftops in Zurich, demonstrating the feasibility of a new energy model and paving the way for the development of residential photovoltaics. Switzerland emerged as the first country to subsidize the installation of photovoltaic facilities.

Four-wheeled solar energy

The first car to be powered through solar cells hits the road in Australia. It’s the Quiet Achiever

The European boom

Europe’s installed photovoltaic power surpasses the 1 GWp mark (peak gigawatt): a 69% growth compared to the previous year, thanks to sustained investments (coming from Germany) and through the spread of purpose-made tax rebates (Italy’s “Conto Energia” scheme). 

The sun rises east, more than ever

Construction on China’s Tengger Desert Solar Park gets underway, slated to become the world’s largest photovoltaic facility.

Innovation, made in Italy

In 2011, Enel Green Power opened its own solar panel factory. Located in Catania, Italy, 3SUN manufactures the world exclusive, cutting-edge bi-facial solar panels featuring HJT technology, guaranteeing high performance in terms of efficiency and low degradation over their lifecycle. True to its namesake - The Sun Factory - our facility works 24/7 to manufacture 1,400 PV panels per day, totalling about 500 thousand each year.

How solar energy works

Photovoltaic and Thermal. Two facets of the same sun

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The core of every solar photovoltaic park is represented by solar panels. Their semiconducting coating - silica, for instance - reacts to visible light and creates energy when hit with solar radiation, thanks to the physical phenomenon known as “photovoltaic effect”. The panels are then mounted on support struts that ensure they’re correctly inclined and oriented so to fully exploit their exposure to light.

In a photovoltaic array, all solar panels are connected to an inverter, basically, a device that transforms the direct current generated by panels in alternating current which is easier to transport and use in all households. A control system is tasked with supervising over the solar park’s operations while ensuring its connection to the grid, so to guarantee the availability of all generated electricity.

One of solar energy’s trump cards is being able to release energy through other types of power plants, also known as “thermodynamic” (or concentrating), in which the sun’s rays can be transformed in electricity through a process by all accounts similar to traditional thermal power plants.

These power plants don’t feature photovoltaic panels, but rather, deploy mirrors that concentrate the sun’s rays towards a specific point, known as “collector”, containing a heat transfer fluid. The searing heat generated by the sun is more than enough to transform this fluid in steam which is, in turn, channeled to a turbine.

The mechanical energy generated by the turbine is sent to the alternator that transforms it into electricity, ready to flow through the power grid.

Photovoltaic cells

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Photovoltaic module

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Solar power stations

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Strong points of solar energy

Powerful, sustainable and quiet

The sky's the limit

The average efficiency of solar panels stands at 20% although technological efficiency is working tirelessly to raise the bar, day after day. Heterojunction technology is now pegged at 24.63% while multi-junction technology is already above 40%.

A scalable resource

From household roofs to large photovoltaic solar parks, solar energy is flexible enough to make it the ideal solution for any kind of personal or business need. 

Carbon and noise neutral

A photovoltaic power plant generates energy in a clean and silent way. Zero C02 emissions and zero decibels make a very compelling case for renewable energy.

Did you know?

The Saharan solar park: an impossible dream, or not?

Nine million square meters and day temperatures soaring above 50° Celsius. If the Sahara desert were a nation, it would rank in fifth place for its size, behind Russia, Canada, China, the United States and above Brazil. Although, since it features only 0.11 inhabitants per square kilometers it would naturally be the less inhabited by far.

Would it be possible to transform the Sahara in one huge solar park that could generate energy on a global scale? Technical difficulties aside, some definitive data on solar energy is surprising. Italian scientific journalist Paolo Attivissimo run the numbers using global energy estimates from 2017 - comparing the consumption levels of 8 billion people with those of Germans - and came up with the idea of a square-shaped solar park with 1000 Km-long sides that could cover the world’s energy supply. Does it sound enormous? Hardly, because it would only take up one-fifteenth of the entire Sahara.

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Discover other renewables energies

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