Evolution of solar energy

Modern Day Compact Solar Street Light

History of Solar:

Studies of the history and development of solar technology lead one to comprehend how essential a role the sun has played in the evolution of mankind. Many ancient civilizations from Egypt, China, India, Africa, Greece, Rome, Mexico, South America, and Europe worshiped the sun as God, especially in societies that were primarily dependent on agriculture and believed the sun could grant prosperity and sustenance. The first sundial, the earliest type of timekeeping device, dates back to 3500 B.C. The Indian observatory Jantar Mantar features many instruments to measure the position and distances of extraterrestrial bodies along with the world’s largest sundial. Sun is the closest star to earth and offers an immense source of energy. Every hour of the day, earth receives around 430 Quintilian joules of energy from the sun and this energy would be sufficient to meet the global energy demands if harnessed as electricity. Over time, the humans have identified the sun not just as a deity but as a sustainable source of energy. The evolution of solar energy has been gradual and today, the solar industry has become a dominant source of renewable power. Though it is assumed by many that the idea of solar panels is a new age technology, the strategic use of the sun for heating and cooling was discovered around 2400 years ago. The Greek philosopher, Socrates observed a phenomenon called passive solar architecture to best utilize the rotation of Earth, where if strategically placed, the homes could get maximum sunlight during winter and minimal sunlight in summer. It has been nearly 200 years since the innovation of solar cells and the technology has been evolving ever since.

Steam Engine Powered by a Solar Reflective Dish

The first meaningful step in solar technology with the discovery of photovoltaic effect happened in 1839 by Alexandre-Edmund Becquerel. It is the effect due to which light energy is converted to electric current in certain semiconductor materials when they are exposed to light. This 19-year-old French scientist was fascinated with the idea of the emission of light without heat (phosphorescence) and during his study of photo-chemical reaction, he started to understand the absorption of energy in the form of light, which eventually led him to the discovery of the photovoltaic effect. In 1861, Auguste Mouchout utilized solar thermal technology to power engines by converting solar energy into mechanical steam power. After the huge demand for coal during the Industrial Revolution, this French engineer and professor was curious to uncover new alternative energy sources and was granted the first solar patent for a steam engine powered by a solar reflective dish. Since the water power was not a portable energy, this was considered a considerable advance in alternative power generating. Solar thermal technology was further developed by John Ericsson, a Swiss-born engineer, in 1870. His design was an interesting variation of Mouchout’s work where he used a trough instead of a dish to reflect the sun’s rays. Unfortunately, he passed away without leaving any blueprints of his design, a design that would have been able to compete with the conventional generation techniques of that time.

Photoconductivity of selenium was discovered by Willoughby Smith in 1873, and the first solar cells were made from selenium in 1883 by American inventor Charles Fritts. The first photoelectric module was made by coating a metal plate with semiconductor selenium with a thin layer of semitransparent gold-leaf film. Fritts reported that despite the intensity of light, the current produced was continuous and of considerable force even though the energy conversion rate was noted to be only 1% to 2%. It was only by 1888 the first solar cell was built by Aleksandr Stoletov based on the outer photoelectric effect which explained why electrons emitted when sunlight was absorbed. Albert Einstein published a paper on the same which brought widespread attention towards solar power technology. He won the Nobel Prize in 1921 for his theories explaining photoelectric cell and quantum light hypothesis. Using this technology, Calvin Fuller, Gerald Pearson, and Darryl Chaplin who were the scientists at Bell Laboratories produced the first modern photovoltaic cell in 1954, where silicon semiconductors were used to convert sunlight into electricity. These cells later became the core of contemporary PV applications. The first generation solar technology could convert sunlight to electricity with only 6% efficiency. The PV panels consisted of wafer-based cells, which were made using materials like crystalline silicon. In 1955, solar cells were sold commercially for the first time by Hoffman Electronics. Vanguard 1, the first satellite to use solar cells, was launched in 1958. These solar cells were cost-effective for space exploration; however, they were not very efficient for terrestrial uses. Hoffman Electronics continued working on PV panels and created more efficient cells but the cells were only used in space flight for a long time. Solar cells were used on U.S. Space Station, Skylab that orbited the earth from 1973 to 1979. During this time period, solar panel technology was expensive for mainstream consumer distribution; however, as the technology continued to evolve, the cost started to decline. Dr. Elliot Berman contributed greatly in making solar panels affordable by using cost-effective materials. This shift in production reduced the price of solar panels, which in turn empowered solar panel technology to compete in the mainstream power market. Due to contributions from Solar Power Corporation, the efficiency of photovoltaic panels increased and the cost of the panels declined over time.

The use of solar panels continued to increase and President Jimmy Carter had solar panels installed at the White House and later, President George H.W. Bush built the National Renewable Energy Laboratory in 1991. The second generation solar technology started to work towards overcoming the technical and physical limitations faced by the scientists of earlier generation. A more diverse range of materials were being used for the production of solar panels such as amorphous silicon cells and cadmium telluride unlike the first generation where the solar panels were silicon based. These new age cells are thin-film solar cells that are made by depositing one or more thin layers of photovoltaic material on a substrate material such as glass or plastic; therefore, the panels were flexible and lightweight. However, the panels required more surface area and some the materials used were noted to be harmful and toxic under certain environmental conditions or during recycling, posing a challenge to design non-polluting PV panels and making them less environment-friendly.

Research and developments continued into the 21st century in the laboratory environments. Changes to the environment increased the need for sustainable energy generation and motivated scientists to put in greater effort into creating highly efficient and commercially viable PV technology. This third generation of solar technology incorporates multiple solar energy technology, including organic photovoltaic (OPV) cells that aim to provide better efficiency while reducing the overall environmental impact of solar panels. PolyPower technology was developed at a nano level to provide a lightweight, flexible and potentially inexpensive approach to solar energy harvesting. In the earlier years, PV panels have been largely limited due to their physical properties. With the use of nano technology, this generation can overcome these challenges and open a world of possibilities. MIT researchers produced ultra-slim, flexible solar cells in 2016. This advancement is still in its early phases but could help widen the use of solar technology in the near future. Continued scientific advancements have made extensive advancements in solar panel technology. The most important factor in panel technology is that the more energy a solar panel absorbs, the more efficient the panel becomes at converting solar energy into electricity. Today, solar panels can deliver at up to 22% efficiency and there have been ongoing efforts to make solar energy even more affordable and efficient.

As a developing nation, India has tremendous potential for generating clean electricity through Renewable Energy Sources (RES) namely Hydro, Bioenergy, Wind and Solar. The country has consciously been trying to reduce carbon footprint by promoting clean energy launched by Jawaharlal Nehru National Solar Mission, which is one of the eight missions under National Action Plan on Climate Change (NAPCC–2008). Being a tropical country, India’s geography allows many regions to receive almost 300 sunny days in a year. The combination of abundant sunshine and the large population in the country makes our country an ideal location for solar market. In a country like ours, various factors like income generation, social development, and health issues influence the demand for sufficient resources. Historically, the amount of greenhouse gas emissions used to be significantly more for the developed economies as compared to the developing countries; however, recent studies suggest that this trend is changing now and is taking an opposite turn. An overwhelmingly large number of private corporations have ventured into the solar PV sector for installations and development throughout various states of the country. Global solar market requires more support from the Governments and if the countries can adjust their polices to make solar equipment more affordable to consumers and encourage renewable energy growth, solar can be expected to dominate the market space over the next decade.