FreeWord – Solar radiation, an unlimited source of energy

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Hi folks. It’s FreeWord time!

Solar radiation is a general term for electromagnetic radiation emitted by the sun. Solar radiation is often referred to as solar energy, and it can be captured and converted into useful forms of energy, such as heat and electricity, by a variety of technologies which has provided many ways to utilize this abundant resource.

Every day, the Earth’s surface receives far more solar irradiation than we can use to power up everything on Earth (the sun delivers more energy to Earth in an hour than we use in a year from fossil, nuclear and all renewable sources combined.) Still, as of 2018, less than two percent of the world’s energy came from solar, but this is all about to change as technology is maturing, and as of today, solar can be a cheaper alternative to fossil fuels.

After the blackness of night, Earth’s star rises on the horizon, spreading her gold in every direction. She comes in the way that natural forces do, needing not invitation yet feeling her welcome. The light is her gift, bold and free, for anyone who cares to open their eyes in the dawn and watch the world awake. This is our sun, a fire ignited to bring warmth to creation and inspire us to seek our own beauty within.

– Angela Abraham

Geographical location

Every location on Earth receives sunlight for at least part of the year. The amount of solar radiation that reaches any one spot on the Earth’s surface varies according to the local landscape, time of the day, season, and is highly dependent on latitude and climate. Overall, the equator receives the most annual solar energy, and the poles receive the least. Also, dry climates receive more solar energy than those with cloud cover.

Advances in Solar Technology

Solar technologies have evolved a lot since they first made their entry in the 1960s. While previous solar photovoltaics (PVs) were seen as a thing of the future, today, technological breakthroughs have positioned the industry for enormous growth. New technological advances and constant improvements in the manufacturing process over the last twenty years have driven the costs associated with solar cells to a steady decrease. The latest technological development encourages solar usage by further decreasing costs and increasing solar panel efficiency.

the sun

Solar Technologies

There are three main ways to harness solar energy: photovoltaics, concentrated solar power, and solar heating & cooling.

Photovoltaics (PV) – is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. PV power generation employs solar panels composed of a number of solar cells. Currently, the most commonly used materials include monocrystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and copper indium gallium selenide/sulfide. Due to the growing demand for solar power, the research and manufacturing of solar cells and photovoltaic arrays are experimenting with new, more efficient materials.

At present, most solar panels are installed on rooftops or immediately adjacent to buildings to provide electricity on-site to power anything from small electronics such as road signs to homes, and large commercial businesses.

Concentrated solar power – systems generate solar power by using mirrors or lenses to concentrate a large area of sunlight onto a small area. The concentrated energy is used to create heat, which in turn creates steam to drive a turbine that generates electrical power.

Solar heating & cooling (SHC) – collects thermal energy from the sun and uses this heat to provide hot water, space heating, cooling, and pool heating for residential, commercial, and industrial applications. These technologies displace the need to use electricity or natural gas.

Alternative Solar Applications

When most people think of solar PV systems, they think of solar panels on rooftops. But researchers are exploring a number of unconventional solar applications that could promise to transform the industry, such as solar roadways, floating solar, space-based solar, and solar power stations in space.

Solar Roadways – Our road network covers an enormous area, and researchers have been exploring ways to use this area to produce electricity by covering it with solar panels/cells. This would help overcome a significant barrier to industrial-scale solar, which is said to take too much land. However, after years of trials, projects around the world have revealed just how expensive it has been to use roads as energy sources after safety and durability factors had to be taken into consideration. 

Floating Solar – Another way to deal with the land-use concerns associated with wide-scale solar is to place solar plants on a structure that floats on a body of water. Since over 70% of the Earth’s surface is covered in water, many countries have started installing solar panels on water surfaces to reduce their use of community areas and forests.

Space-Based SolarBeam – scientists are resurrecting a technology that was first tested more than forty years ago; space-based satellites capture sunlight and turn it into microwave energy, which is then beamed back to earth. This type of technology promises to capture far more sunlight (almost ninety percent) because satellites can be positioned to optimize light capture around the clock. India, China, and Japan are currently investing heavily in these technologies. 

Solar Power Stations In Space – Some scientists believe that giant, space-based solar farms could provide an environmentally-friendly answer to the world’s energy crisis.

Above the Earth, there’s no day and night cycle and no clouds or weather or anything else that might obstruct the sun’s ray, so a constant power source is available.

Ali Hajimiri, professor of electrical engineering at the California Institute of Technology and co-director of the university’s Space Solar Power Project.

China is planning to build the world’s first solar power station in Earth’s orbit to provide “inexhaustible, clean energy” according to a story in Science and Technology Daily, the official newspaper of China’s Ministry of Science and Technology. 


A solar panel system consists of hundreds, sometimes thousands, of solar cells that separately convert the radiant sunlight into electrical currents. As of today, the average solar cell has about 15% efficiency, which means that there is plenty of room for improvement. Researchers are in the constant process of experimenting with new techniques to enhance light capture and conversion. The two most promising recent discoveries are colloidal quantum dots and Gallium Arsenide.

Colloidal quantum dots – a new type of light-sensitive nanoparticle that can offer a cheaper and more flexible material for solar cells. The new materials use n-type and p-type semiconductors and are suitable for outdoor use, unlike the previous designs that weren’t capable of functioning outdoors and therefore not practical applications for the solar market. The researchers discovered that n-type materials bind to oxygen, the new colloidal quantum dots don’t bind to the air and therefore can maintain their stability outdoors. This helps to increase radiant light absorption and results in up to eight percent better efficiency. 

Gallium Arsenide – recently discovered material that could make solar PV systems nearly three times more efficient. These solar cells are called “triple junction cells,” and they’re much more efficient because they can be chemically modified in a way that optimizes sunlight capture. The model uses a sensor-controlled window curtain that can track sunlight, as well as “light pipes” that direct light into the system.


Solar energy is the key to a clean energy future. The sun is a powerful source of energy that can help our planet by giving us clean, reusable energy to power our world. This energy is free, does not create pollution, and if used wisely, can help us become less dependent on fossil fuels. The challenge for the solar industry is in resolving how to efficiently and economically convert this energy into usable electricity.

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