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Wiki defines Solar Energy as “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”.

Forms of Energy

There are two forms of energy:

Kinetic Energy : The energy that a body possesses by virtue of its motion is known as its Kinetic Energy. The most generic representation of Kinetic Energy is KE = (1/2)mv2, where m is the mass of the body and v is the velocity at which it travels. This representation changes a little in case of rotational rigid bodies, although the form remains same. Kinetic energy is a scalar quantity which means it just has a magnitude and no direction.

Potential Energy :  Potential energy is the energy possessed by a stationary body in a force field. A force field can take many types – gravitational, electric, magnetic, etc.

Other Types of Energy

Thermal or Heat: Thermal energy is nothing but energy that an object possesses or a system possesses due to the movement of particles within the object or the system. The energy is pushed into motion by using heat, for e.g. fire in your fireplace, a hot cup of tea.

Chemical: Chemical Energy is something that is stored in the bonds of chemical compounds (atoms and molecules). It is then released in the form of a chemical reaction, which produces heat as a by-product (exothermic reaction). The energy is caused by chemical reactions, for e.g. food when it is being cooked, the glucose in our bodies.

Electrical: Electrical energy is stored in charged particles inside an electric field. Electric fields are basically areas that surround a charged particle. The energy happens when electricity creates motion, light or heat. For e.g. the electric coils on your stove.

Gravitational: When we lift a box from a surface like ground by using energy in our arm muscles, what really happens to that energy? The answer is that it gets converted into gravitational potential energy. Gravitational potential energy, or GPE, can be described as height energy. So, the higher up an object is placed, the more GPE it has. The energy is transferred as a result of work done by gravity, for e.g. water falling down a waterfall, roller coaster, and reservoirs.

Magnetic: Magnetic energy is there inside a magnetic field, which leads to various metals either repelling or attracting each other. The energy results from magnetic field of a magnet or a current carrying wire.

Nuclear: Nuclear energy is stored in the nucleus (core) of an atom. Atoms can be described as tiny particles that make up every object in the universe. There is massive energy in the bonds that hold atoms together, so nuclear energy can be easily used to make electricity. This is the energy from interactions between the protons and neutrons

Overview of Conventional Sources of Energy

  • Conventional sources of energy have been in use for a long time. Example: petroleum, coal, water power and natural gases.
  • They also lead to pollution as they emit smoke and ash when they are used.
  • They are high-maintenance and expensive.
  • The preservation cost is very high as they need to be stored and then converted because they are sent through transmission lines and grid.

of an atom. Examples are fission and fusion.

What is Renewable Energy?

Renewable energy is energy that is generated from natural resources that are continuously replenished. This includes sunlight, geothermal heat, wind, tides, water, and various forms of biomass. This energy cannot be exhausted and is constantly renewed.

These days, using terms like renewable energy, green energy and clean energy are all becoming more and more common. Most of us are aware that wind energy and solar energy are renewable energy sources. But do you know the other things on the list? Apart from the popular names like wind and solar, there are in fact a ton of renewable energy sources. Mainly, anything that can be used to create energy that will quickly renew is nothing but a form or source of renewable energy.

Firstly, it’s crucial to understand that what conventional energy sources are. Conventional sources have been used from ancient times and include materials like coal, natural gas, oil, and firewood.

Solar energy refers to energy from the sun. The sun has produced energy for billions of years. It is the most important source of energy for life forms. It is a renewable source of energy unlike non-renewable sources such as fossil fuels. Solar energy technologies use the sun’s energy to light homes, produce hot water, heat homes and electricity.

World׳s energy demand is growing fast because of population explosion and technological advancements. It is therefore important to go for reliable, cost effective and everlasting renewable energy source for energy demand arising in future. Solar energy, among other renewable sources of energy, is a promising and freely available energy source for managing long-term issues in an energy crisis. The solar industry is developing steadily all over the world because of the high demand for energy while major energy source, fossil fuel, is limited and other sources are expensive. It has become a tool to develop the economic status of developing countries and to sustain the lives of many underprivileged people as it is now cost effective after long aggressive research done to expedite its development.

The solar industry would definitely be the best option for future energy demand since it is superior in terms of availability, cost effectiveness, accessibility, capacity, and efficiency compared to other renewable energy sources. This paper, therefore, discusses the need of solar industry with its fundamental concepts, worlds energy scenario, highlights of researches done to upgrade solar industry, its potential applications and barriers for the better solar industry in future in order to resolve the energy crisis.

The consumption of non-renewable sources like oil, gas, and coal is increasing at an alarming rate. The time has finally come to look after some other renewable sources of energy i.e. solar, wind and geothermal energy. Although many countries have started utilizing solar energy extensively but still have to go a long way to exploit this energy to fulfill their daily demands. Here are few facts on solar energy that can help you assess the potential of solar energy to meet global requirements.

Solar energy is the most readily available source of energy. It does not belong to anybody and is, therefore, free. It is also the most important of the non-conventional sources of energy because it is non-polluting and, therefore, helps in lessening the greenhouse effect. It has been used since prehistoric times, but in a most primitive manner. Before 1970, some research and development was carried out in a few countries to exploit solar energy more efficiently, but most of this work remained mainly academic. After the dramatic rise in oil prices in the 1970s, several countries began to formulate extensive research and development programmes to exploit solar energy.

When we hang out our clothes to dry in the sun, we use the energy of the sun. In the same way, solar panels absorb the energy of the sun to provide heat for cooking and for heating water. Such systems are available in the market and are being used in homes and factories.

In the next few years it is expected that millions of households in the world will be using solar energy as the trends in USA and Japan show. In India too, the Indian Renewable Energy Development Agency and the Ministry of Non-Conventional Energy Sources are formulating a programme to have solar energy in more than a million households in the next few years. However, the people’s initiative is essential if the programme is to be successful.

India is one of the few countries with long days and plenty of sunshine, especially in the Thar desert region. This zone, having abundant solar energy available, is suitable for harnessing solar energy for a number of applications. In areas with similar intensity of solar radiation, solar energy could be easily harnessed. Solar thermal energy is being used in India for heating water for both industrial and domestic purposes. A 140 MW integrated solar power plant is to be set up in Jodhpur but the initial expense incurred is still very high.

Solar energy can also be used to meet our electricity requirements. Through Solar Photovoltaic (SPV) cells, solar radiation gets converted into DC electricity directly. This electricity can either be used as it is or can be stored in the battery. This stored electrical energy then can be used at night. SPV can be used for a number of applications such as:
a. Domestic lighting
b. Street lighting
c. Village electrification
d. Water pumping
e. Desalination of salty water
f. Powering of remote telecommunication repeater stations and
g. Railway signals.

If the means to make efficient use of solar energy could be found, it would reduce our dependence on non-renewable sources of energy and make our environment cleaner.

The history behind Solar Energy

Solar energy has been used by humans for thousands of years.  For example, ancient cultures used energy from the sun to keep warm by starting fires with it.  They also kept their homes warm through passive solar energy designs. Passive design solar home use the natural movement of heat and air to maintain comfortable temperatures, operating with little or no mechanical assistance. It’s called passive solar because the design of the home maximizes the benefits it receives from the sun with standard construction features. Passive solar takes advantage of local breezes and landscape features. It uses a simple system with the help of shade trees and windbreaks to collect and store solar energy with no switches or controls. Buildings were designed so that walls and floors collected solar heat during the day that was released at night to keep them warm.  If you have ever stood in the sun to get warm then you too have utilized solar thermal energy.

Edmond Becquerel, a French physicist first showed photovoltaic activity in 1839. He found that electrical current in certain materials could be increased when exposed to light. Sixty-six years later, in 1905, we gained an understanding of Edmonds’ work when the famous physicist Albert Einstein described the photoelectric effect. It is the principle on which photovoltaics are based.  In 1921 Einstein received the Nobel Prize for his theories on the photoelectric effect.

Solar cells of practical use have been available since the mid 1950’s when AT&T Labs first developed 6% efficient silicon solar cells.  By 1960 Hoffman Electronics increased commercial solar cell efficiencies to as much as 14% and today researchers have developed cells with more than 20% efficiencies.  20% efficient means that out of the total energy that hits the surface of a solar cell, about 20% is converted into usable electricity.

The first long-term practical application of PV cells was in satellite systems.  In 1958 the Vanguard I, was launched into space.  It was the first orbiting vehicle to be powered by solar energy.  Photovoltaic silicon solar cells provided the electrical power to the satellite until 1964 when the system was shut down.  The solar power system was so successful that PV’s have been a part of world-wide satellite space programs ever since.  The sun provides endless non polluting energy to the satellite power systems. The demand for solar cells has also risen as a result of the telecommunications revolution and need for satellites.

The energy crisis of the 1970’s and the associate oil embargos made many nations aware of their dependency on controlled non-renewable energy sources and this fueled exploration of alternative energy sources.  This included further research into renewable sources such as solar power, wind power and geothermal power.

In 1970’s an economic breakthrough occurred. Dr. Elliot Berman designed a less expensive solar cell bringing the price down from $100 per watt to $20 per watt. These huge cost savings opened up a large number of applications that were not considered before because of high costs.  These applications included railroads, lighthouses, off-shore oil rigs, buoys, and remote homes.  For some countries and many applications, solar energy is now considered a primary energy source, not an alternative.

What is Solar Energy?

The first law of thermodynamics, also known as the Law of Conservation of Energy, states that

  • Energy can only change from one form to another.
  • Energy can not be created or destroyed.

Solar Energy is the energy from the Sun.  The Sun is a big ball of heat and light resulting from nuclear fusion at its core.  The nuclear reaction releases energy that travels outward to the surface of the Sun.  Along the way to the surface the energy transforms so that by the time it is released it is primarily light energy.  Sunlight.  The two major types of solar energy that make it to Earth are heat and light. Solar energy is also called “alternative energy” to fossil fuel energy sources such as oil and coal.

What is Solar Power?

The word solar stems from the Roman word for the god of the sun, Sol.  Therefore, the word solar refers to the Sun and ‘solar power’ is power from the Sun.

When we say something is solar powered, we mean that the energy it uses for power came directly from solar energy or sunlight energy.  The sun provides Earth with 2 major forms of energy, heat and light.  Some solar powered systems utilize the heat energy for heating while others transform the light energy into electrical energy (electricity).

There are many practical applications for solar power that are in use today.
There are vehicles that run on solar power.  Some have PV panels as a direct power source that convert light energy into electricity to power their motors.  Since those cars will not run when the sun is not available it is more practical to have a car powered by batteries that can be recharged with solar energy.
In countries and locations where traditional power sources are not available it is more economical to power a house with solar energy.  To these people, solar is not an alternative energy; it is their primary energy source.

The Sun and Solar Energy

The sun is a star.  It is the largest object in our solar system and one of the larger stars in our galaxy.  The source of energy in the Sun is at its core where hydrogen is converted to helium in a thermonuclear reaction.  This energy travels from the core to the surface of the Sun and is released into space primarily as light.  The energy that comes to the Earth is in 2 main forms, heat and light.

Every hour, enough sunlight energy reaches the Earth to meet the world’s energy demand for a whole year.

1) U.S. Department of Energy

The amount of energy from the Sun that reaches the Earth annually is 4 x 1018Joules.
4 x 1018 Joules/ Year ÷ 365 Days/ Year = 1 x 1016 Joules/ Day
1 x 1016 Joules/ Day ÷ 24 Hours/ Day = 4 x 1014 Joules/ Hour
The amount of energy consumed annually by the world’s population is about 3 x 1014 Joules.

2) Speed of Light Energy from the Sun to Earth.

The earth is the third planet from the sun at a distance of about 93,000,000 (93 million) miles.  If you could pitch a fast baseball to the sun at 100 miles per hour (mph) it would take the ball over 100 years to get there.  On the other hand, it only takes light energy 8½ minutes to reach the earth from the surface of the sun, traveling at the speed of light of course.

3) Pitching a Baseball at 100 mph to the Sun

93,000,000 miles ÷ 100 miles/ hour = 930,000 hours to reach the Sun.;

930,000 hours ÷ 24 hours/ day = 38,750 days to reach the Sun;

38,750 days ÷ 365 days per year = 106.16 years to reach the Sun.

4) Light Energy traveling to Earth

The speed of light is equal to about 11,000,000 (11 million) miles/ minute.

93,000,000 miles ÷ 11,000,000 miles/ minute 

= 8.45 minutes for light  to travel from the Sun to Earth.

What are Solar Panels?

Image result for Solar energy
Solar Panel

Solar panels collect heat energy from the sun. We call this heat solar thermal energy. A simple example of a solar panel is a closed box with a top made of a transparent material such as glass or plastic.

The sun shines through the glass and heats up the inside of the box. This is the same type of heating that happens to the inside of a car when it sits in the sun. In some cases the inside of the box is painted black so that it absorbs more heat. The heat that is collected inside the box can then be used for several purposes. The most common uses for solar panels is to heat air or water.

A system that uses solar thermal energy to heat air is not complex. A transparent top is attached to a box. The box has an inlet pipe for cool air. The cool air can be pushed into the box using a fan. The cool air moves through the inlet pipe into the box. Inside the box the air is warmed by the heat energy from the sun rays. As more cool air is pushed into the box the warm air is forced out the other end of the box through the outlet pipe. The warm air can now be used to heat something like your home. Some very large systems use a solar panel on the roof of a house to heat a whole room.  The warm air in that room is then blown through vents to heat the whole house.

Solar panels that are designed to heat water work almost the same way as ones designed to heat air. In a simple example there is a pipe that runs through the inside of the box.

The sun rays heat the air inside the box. The heat in the air is transferred to the pipes then the heat in the pipes is transferred to the water. As cool water is pumped into the inlet pipe the warm water is forced out of the outlet pipe. We can now use this warm water for something like a bath or shower.

These pictures are only a simple representation of the basic concepts.  In practice, solar water and air heaters can be more complex.

The terms “Solar Panel” and “Photovoltaic Panel” describe two different devices.  We use the terms as follows:

  • A Solar Panel collects and utilizes heat energy from the sun.
  • A Photovoltaic Panel transforms light energy into electrical energy.

What are Photovoltaic (PV) Panels?

Photovoltaic Panels are are used to transform sunlight energy into electrical energy.  ”PV panel” is the common name for a photovoltaic panel.  Literally translated photovoltaic means “light-electricity”.

Photovoltaic means “light-electricity”.  It is formed from photo- which means light and -voltaic which means electrical current or electricity.

PV panels are made up of smaller sections called solar cells.  Solar cells, like batteries, each have a rated value of voltage (V or volts) and amperage (A or amps).  The total power in wattage (W or watts) delivered is the voltage times the amperage.

Volts x Amps = Watts or V x A = W

Batteries can be arranged in parallel or in series depending on the requirements of the device we want to power.

  • In parallel the amperage is additive and the voltage is constant.  
  • In series the voltage is additive and the amperage is constant.

Solar Cells or Panels can also be arranged in parallel or series

  • In parallel the amperage is additive and the voltage is constant. 
  • In series the voltage is additive and the amperage is constant.

Solar cells are connected and arranged into a single panel.  The standard panel sizes are 12 volt and 24 volt.

The terms “Solar Panel” and “Photovoltaic Panel” describe two different devices.  We use the terms as follows:

  • A Solar Panel collects and utilizes heat energy from the sun.
  • A Photovoltaic Panel transforms light energy into electrical energy.

What are Solar Cells?

Solar cells are devices which convert solar light energy directly into electricity and function by the photovoltaic effect.  Photo- means light and -voltaic means electrical current or electricity  (light-electricity).  A solar cell provides direct current (DC) electricity that can be used to power DC motors and light bulbs among other things.  Solar cells can even be used to charge rechargeable batteries so that electricity can be stored for later use when the sun is not available. The fully charged batteries are portable energy that can be used whenever and wherever they are needed.

Solar cells provide DC electricity similar to batteries however, batteries differ because they operate through a process known as an electrochemical reaction. An electrochemical reaction is a process in which electrons flow between a solid electrode and substance, such as an electrolyte. This flow triggers an electric current through the electrodes, causing the reaction to liberate or absorb heat.Under different conditions, other types of reactions create an electric current flow. For example, two electrodes in contact with each other result in a reduction and oxidation (redox) reaction, causing a change in the oxidation numbers of all atoms that are part of the reaction.


Few Reasons why Solar Energy is a Resource of the Future:

Increasing Demand: Most industries would salivate over the solar sector’s current growth. Last year, demand for solar power in the U.S. increased by 41 percent, making it the second-biggest new source of energy generation after natural gas. Residential projects leapt even higher, surging 60 percent over the previous year. Overall 4.75 gigawatts of photovoltaic panels were installed in 2013, enough to power over three-and-a-half million homes. It was, according to industry analysts, a pivotal year. “2013 offered the U.S. solar market the first real glimpse of its path toward mainstream status,” one expert told Time magazine. And the growth shows no signs of stalling: in August, Merrill Lynch issued a report to investors advising them to pour their money into solar stocks, which the firm expects to soar in value over the next three years.

Cost Effectiveness of the Solar Panels: There are not many products that can say they’re getting cheaper by seven percent per year. That’s the cost trajectory for solar voltaics according to John Farrell, director of the Energy Self-Reliant States and Communities program at the Institute for Local Self-Reliance. In fact, according to Forbes, solar is already cheaper than utility power in several states on a dollar-per-kilowatt-hour basis — it’s only installation costs that keep it more expensive overall. But those installation costs may soon fall. Aiming to make solar energy cost competitive with other forms of electricity by the end of this decade (a cost the government identifies as six cents per kilowatt hour), the U.S. Department of Energy has launched the SunShot initiative, an array of efforts to drive down the cost of installing and maintaining solar panels.

China opting for a cleaner Energy Source: Complicating the view of China as a rampant polluter, a major reason that solar is growing the world over is thanks to cheap Chinese panels. Subsidies from the Chinese government have helped companies in that country capture half the world’s solar panel manufacturing market, up from 20 percent in 2008. China shows no signs of slowing its output, adding that “PV (photovoltaics) is becoming ever cheaper and simpler to install.”

Solar Energy as Good Investment: From 2012 to 2013, commercial deployment of new solar installations grew by 40 percent, with over 32,800 facilities utilizing solar energy. A survey of the Fortune 100 companies by the Solar Energy Industries Association found that the top 25 had increased their solar capacity significantly, from 300 megawatts at 730 facilities in 2012 to 445 megawatts at 950 facilities in 2013. That means that those businesses are no longer just taking a chance on solar — they’ve seen its performance and decided to double down on it.

What does Solar Energy have in store for the future?

Opportunities for New Business: Every new technology brings new opportunities for business. Tesla and Panasonic are already planning a humongous solar panel manufacturing factory in Buffalo, New York. Tesla’s Powerwall is already one of the most popular domestic energy storage devices in the world. The big players aren’t the only ones benefitting from the solar energy boom.

There is likely to a be a lot of demand for real estate. Landowners and farmers can lease out their land for the construction of new solar farms. Demand for medium voltage cable could rise since solar farms will need to be freshly connected to the grid.  All the new opportunities will drive prices lower and drive the tech further.

Bio-Solar Cells: Researchers have experimented with biological material in solar cells for a while now. Bacteria (specifically cyanobacteria) can eventually make it easier to power wireless devices. The efficiency of these bio-solar cells is nowhere close to conventional PV cells, but there is hope the technology will gradually catch up. One of the researchers at the Binghamton University’s Thomas J. Watson School of Engineering and Applied Science, Seokheun ‘Sean’ Choi, believes bio-cells would be useful for remote areas where replacing batteries frequently isn’t an option.

Better Conversion to Electricity: Researchers from Israel and Germany partnered up to study if there was a better way to convert sunlight into electricity. Turns out that the most efficient way is also the most common – photosynthesis. The study confirmed that using biomass as fuel could eventually allow us to create artificial photosynthesis machines. These could convert sunlight into energy and store in a more natural way for later use.

Floating Panels: Some countries lack the space for solar farms. An elegant solution to this problem is floating solar farms. Ciel & Terre International, a French energy company, has been working on a large scale, floating, solar solution since 2011. They have already installed a trial farm off the coast of the UK and are now looking at attempting similar projects in India, France, and Japan.

Wireless Power From Space: The Japanese Space Agency (JAXA) believes getting closer to the sun is the best way to drive efficiency and collect more power. The team’s Space Solar Power Systems (SSPS) project is trying to send solar panels to near-Earth orbit. The power collected will be wirelessly transmitted back to base station via microwaves. If successful, this technology could be a true game changer.

Energy Harvesting Trees: A team of researchers in Finland is trying create a tree that stores solar energy in its leaves. These leaves could then be used to power small appliances and mobile phones. The trees are likely to be 3D printed, using biomaterials that mimic organic wood. Each leaf generates power from sunlight, but can also use kinetic energy from the wind. The trees are designed to survive indoors as well as outdoors. The project is currently in the prototype phase.

Energy storage methods

The energy harnessed in form of solar power can be stored as heat at temperatures that can be used for domestic purposes by using materials with high specific heat capacities like earth, stone or water using Thermal storage systems. The advantages of thermal power systems is their ability to reduce overall heating and cooling demands and reduce demand at peak use timings and thereafter create a shift of the use of the energy to the off-peak hours.

Apart from the above, readily available materials like Glauber’s salt and paraffin wax can also be used as thermal storage medium to maintain temperatures between approximately 64 °C or 147 °F. For storage of the harnessed solar energy at high temperatures, molten salts can be used due to their high specific heat capacity and comparatively low-costs. An example of this thermal storage system is the Solar Two project, which boasts 68 m³ storage tank that stores approximately 1.44 terajoules of energy, with an average storage efficiency of close to 99% every year.

The solar energy can also be stored as Pumped-storage hydroelectricity, where massive amount of energy is generated upon releasing the water from its elevation. Also, excess electricity can be stored using rechargeable batteries in off-grid PV systems. Where any electricity that is in excess can be transmitted to the grid.

Production of solar energy

With the huge demand of electricity across the globe with technological advancement and the growing population, the solar power can serve as a renewable and reliable source of power generation. Solar power is generated using Concentrated Solar Power, wherein the sunlight from a vast expanse of area is focused into a beam using mirrors and lenses or using Photovoltaics which have the ability to convert sunlight into current using the phenomenon photoelectric effect. With more and more large construction and commercial sectors shifting to solar power, it can easily become the major source of electricity generation by the 2050s. Currently, the largest solar power project in the world is Ivanpah Solar Power Facility, which generates approximately 392 MW of power.

The major advantages of solar energy are listed below:

  • It is a renewable source of energy that can support the energy requirements of the global populations for a few hundreds of generations.
  • Harnessing the solar energy does not cause any pollution.
  • Upon a single installation of solar panel, solar power can be generated thereafter totally free of cost.
  • Not only it has low maintenance costs, the power generated from the solar panels can go a long way in reducing the expenses owing to electric bills.
  • With advancements in technology, solar power is finding use in diverse applications, with a continued increase in the effectiveness of energy generation by the solar panels.

Some of the major disadvantages of solar energy are as follows:

  • The weather dependency of the solar panel is the major limitation. The lowered efficiency on rainy and cloudy days and nights or at winter times makes thermodynamic panels a better alternative.
  • The initial cost of installation of a solar panel is very high, despite the incentives provided by the governments.
  • The storage of solar power requires large batteries that need to be charged to ensure their usage in nights or wintertime, when sunlight is low. These batteries add to the cost of solar power maintenance and usage.
  • The installation of large panels requires a huge amount of space.
  • The green house gases emitted upon installation of solar panels adds to the pollution levels, although it is comparatively less as compared to other sources of energy.

Solar energy is clearly the future. Until now, humanity has only scratched the surface of the sun’s true potential. The sun deploys more energy to the planet’s surface than what is used every year. While the costs have reduced drastically over the years, the technology has remained the same. Researchers across the globe are working tirelessly to improve the way the sun’s rays are collected and converted into energy.

The relentless drive of technology will eventually help solar energy contribute a major part in the energy needs of the future. Better and more efficient devices will be powered by the sun and have the ability to store this energy for longer periods. The coming energy boom is set to change lives forever.

As we step into the future of Solar Energy, we are reminded of the prophetic words of Frank Shuman, as quoted in the New York Times on 2nd July 1916,”We have proved…that after our stores of oil and coal are exhausted the human race can receive unlimited power from the rays of the sun”.

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