Month: October 2018

Solar revolution: Evolution of photovoltaic technology in the 21st century

In the previous article, we discussed the first-stage evolution of photovoltaic technology. It was the biography of photovoltaic technology before the beginning of the 21st century.

What happened in the 21st century?

Latest trends in solar photovoltaic technology

It is interesting to know that the worldwide cumulative photovoltaic capacity merely stood at about 95 kW in 1968. It took almost three decades to reach 950 MW in 1998. The cumulative worldwide installation had been growing at a snail’s pace until about 2000 and reached a milestone of 1000 MW in 1999 [2]. Showing a green light for a greener world, the cumulative capacity which was about 8 GW in 2007, nearly doubled to hit 15 GW of capacity in 2008 [3]. Since then, the capacity started expanding swiftly, as it can be seen in the following table and column chart.

Table 01: Worldwide cumulative and added photovoltaic capacity [3]

According to above table, as much as 98 GW of solar photovoltaic capacity has been added in 2017 thereby raising the worldwide cumulative capacity to 402 GW which is now comparable with worldwide cumulative solar hot water capacity. Worldwide cumulative solar hot water capacity has grown by merely 16 GW and reached 472 GW in 2017. This reveals a continuous decline in annual growth whilst solar photovoltaic technology is showing an overwhelming progress. Following bar chart clearly illustrates how fast worldwide cumulative photovoltaic capacity has been growing during the recent past [3].

Figure 01: Worldwide cumulative and added photovoltaic capacity [3]

What is behind the boom?

As we can see it, the cumulative photovoltaic capacity has now been growing fast, but it was not until 1998 which seems to be a pivotal point in the photovoltaics’ history. What is behind the sudden increase in worldwide installations?

We can identify a lot of forces attempting to shift the world’s energy interest towards solar photovoltaics. Let us discuss some of the most vigorous forces.

• Cost reduction:

Prior to the beginning of the 21st century, there was a lot of impedance to the commercialization of photovoltaic technology. It was too expensive for commercial implementations compared to fossil fuels and also other renewable energy technologies like hydropower, wind power, and concentrating solar thermal. Price of solar photovoltaic modules has been continuously falling and eventually, photovoltaics became economically viable and competitive with the fossil fuel prices. The continuous drop in the price is what made it the most popular and fastest-growing renewable energy technology in the 21st century. Price is forecast to drop further attracting more and more investments.

• Environmental concerns:

Even in the 1950s, people worried a lot about the possible detrimental effects of climate change. Fossil fuel burning was the main suspect. Not only scientific community, even government bodies and private organizations actively started fighting the climate change leading to many achievements such as the Kyoto protocol in which state parties committed reducing greenhouse gas emissions. The best way to did it was switching to renewable energy sources as soon as possible. Many countries introduced attractive renewable energy policies to promote solar PV and encourage the public to invest in solar PV. Thanks to such government support and falling price of solar PV, investing in solar PV has now become a win-win for each party involved in.

• Increasing price and rapid depletion of fossil fuels:

Our primary sources of energy, fossil fuels are rapidly depleting due to heavy consumption whilst price is increasing. This trend naturally forces to search for potential alternatives. Price of solar PV modules is already competitive with most of the other renewable energy technologies. Increasing price of fossil fuels, and rapid depletion of fossil fuels direct more attention towards photovoltaics.

• Improved efficiency:

Efficiency of solar photovoltaics is being improved day by day. A number of photovoltaic technologies have been developed with different efficiencies. Multi-junction concentrated solar cells offer the highest efficiencies but are too expensive. Single crystalline and polycrystalline silicon solar cells also offer reasonable efficiencies yet still are cost-effective than most of the other types of photovoltaics. Various state of the art technologies (Tandem solar cells, PERC, etc.) have already been employed successfully, leading to more efficient photovoltaics.

These unique features make solar photovoltaics an ideal alternative to depleting fossil fuels. There is now no any other type of renewable energy technology to compete with photovoltaics. In fact, there were several competitors in the past namely hydropower, concentrating solar thermal, and wind power. However, most of the potential hydropower sources are already being exploited and thus hydropower capacity has been reaching a plateau. Furthermore, when capital investment, space-efficiency, environmental impact, payback time, etc. are taken into consideration, photovoltaic technology is more practically viable than concentrating solar thermal, and wind power. It is not a rhapsody. Take a look at the following bar chart. It clearly depicts that solar photovoltaics was the fastest-growing renewable energy technology which added 98 GW of power in 2017. This is nearly twice the capacity added by wind power during the same year. Wind power, hydropower, bio power, and geothermal power have added 52 GW, 19 GW, 8 GW, and 1 GW of power, respectively, in 2017.

Figure 02: Capacity added by different renewable energy technologies in 2017 [3]

To sum up, photovoltaic technology has evolved to be a commercially viable and technically feasible technology capable of providing an unimaginable amount of energy to meet mankind’s energy demand, making the world greener and sustainable. With continuous research and development, it would continually be evolving and revolutionizing the world with impressive benefits.

It is real!

We are all witnesses!

References

[1] Harmon, C. (2000). Experience curves of photovoltaic technology.

[2] Guha, S. (2005, January). Can your roof provide your electrical needs?-the growth prospect of building-integrated photovoltaic. In Photovoltaic Specialists Conference, 2005. Conference Record of the Thirty-first IEEE (pp. 12-16). IEEE.

[3] REN21. 2018. Renewables 2018 Global Status Report (Paris: REN21 Secretariat).

In the previous article, we discussed how solar photovoltaics technology had been impressing the world with an unexpected growth in the cumulative capacity. It was evident that the concentrating solar thermal technology was being trampled by increasingly efficient photovoltaic technology.

How photovoltaic technology did it?

Well. Let us discuss in details.

First of all, we need to have a pretty good grasp on how photovoltaic technology has been evolving. Then it would be easy to understand how it succeeded in the energy industry.

Evolution of solar photovoltaics technology

Following is some historical milestones reached by the solar photovoltaic technology in the past.

• 1839: The photovoltaic effect was first discovered by a French scientist Edmond Becquerel for the first time [1]. It laid the foundation stone of a new era leading to a greener world.
• 1873: Willoughby Smith discovered photoconductivity in selenium [2]. It was the second step in making practically viable solar cells.
• 1876: Richard Evans Day and William Grylls Adams found that selenium was capable of converting light into electricity. It was not efficient enough at converting sunlight into electricity, however, it was the very first time to observe a solid material generating electricity upon exposure to light [3]. So, this discovery was a mammoth leap towards a state of the art renewable energy technology.
• 1883: The first solar cell was built and described by an American inventor Charles Fritts. His technology was based on selenium wafers [4].
• 1916: Polish engineer Jan Czochralski introduced a method to grow single-crystal silicon [5]. His discovery led to fabricate more efficient single crystal silicon solar cells.
• 1932: Photovoltaic effect was discovered in CdS by Audobert and Stora [6]. His discovery paved the way for a new type of solar cells such as CdS/CdTe.
• 1953: Dr. Dan Trivich who had been working in Wayne State University made the first theoretical calculation of conversion efficiencies of different materials with different band gaps based on the spectrum of the Sun [7].
• 1954: Bell laboratories brought to light information about a groundbreaking discovery. They proved that silicon was more efficient than selenium at converting light into electricity demonstrated a solar module which was the first ever solar module capable of generating a viable amount of electricity [8].
• 1957: Hoffman electronics claimed to have developed 8% efficient solar cells [9].
• 1958: Hoffman electronics claimed to have developed 9% efficient solar cells [10].
• 1959: Hoffman electronics claimed to have developed 10% efficient solar cells [11].
• 1960: Hoffman electronics claimed to have developed 14% efficient solar cells [12].
• 1962: The first commercial telecommunication satellite, Telstar was launched by Bell telephone laboratories [13]. It was the first commercial use of solar cells in space.
• 1966: The first astronomical observatory (orbiting around the Earth) with a 1 kW photovoltaic array was launched by NASA [14].
• 1976: David Carlson and Christopher Wronski developed the world’s first amorphous silicon photovoltaics which had an efficiency of 1.1% [15].
• 1978: The world’s first village-based solar photovoltaic system (For residents of Schuchuli) was installed with a capacity of 3.5 kW. The system had been providing electricity needed for lighting, refrigeration, and water pumping until the village was connected to the national grid. In addition, the project had had a communal washing machine and sewing machine. This project can be seen as a paradigm of stand-alone solar photovoltaic village system [16].
• 1982: World’s first megawatt-sized solar photovoltaic project developed by ARCO Solar, began its operation. Covering 20 acres of land and employing dual-axis solar trackers, it had a record capacity of 1 MW [17].
• 1990: University of South Wales announced to have exceeded 20% efficiency limit under space illumination for silicon solar cells [18].
• The 1000-roof program in Germany was launched [19]. Its success triggered a chain reaction in solar photovoltaic installations, all over the world.
  1992: Braking the efficient limit of 15%, University of South Florida announced 15.9% efficient thin film solar cells (CdTe) [20].
• 1994: The first two-terminal monolithic cell to exceed 30% efficiency limit was announced. Unlike conventional silicon solar cells, they were made of gallium indium phosphide and gallium arsenide. The efficiency peaked at 30.2% in a concentration range of 140-180 suns owing to increase in the open circuit voltage and fill factor [21].

The darkest hour is just before the dawn

Solar photovoltaic technology was too expensive for terrestrial applications even in the 1990s. Therefore, it was not used if grid electricity was available. However, the technology was quite technically feasible in remote locations where grid electricity was not available. Thanks to such applications, the cumulative solar photovoltaic capacity had been growing but only at a snail’s pace until beginning of the 21st century. Thereafter, the growth in the world’s cumulative photovoltaic capacity has been drawing an exponential line! This unexpected growth can be largely attributed to the increasing light-to electricity efficiency, cost reduction and also the increasing price of fossil fuels and environmental concerns over fossil fuel burning. In the next article, let us discuss how photovoltaic technology has been evolving from the end of the 20th century.

Reference
[1] Shah, A., Torres, P., Tscharner, R., Wyrsch, N., & Keppner, H. (1999). Photovoltaic technology: the case for thin-film solar cells. science, 285 (5428), 692-698.

[2] Jenkins, T. (2005). A brief history of… semiconductors. Physics education, 40 (5), 430.

[3] Bilal, M., Arbab, M. N., Afridi, M. Z. U. A., & Khattak, A. (2016). Increasing the Output Power and Efficiency of Solar Panel by Using Concentrator Photovoltaics (CPV). International Journal of Engineering Works, 3 (12), 98-102.

[4] Jean, J., Brown, P. R., Jaffe, R. L., Buonassisi, T., & Bulović, V. (2015). Pathways for solar photovoltaics. Energy & Environmental Science, 8 (4), 1200-1219.

[5] Lukanin, D., Kalaev, V., & Zhmakin, A. (2003, September). Parallel simulation of Czochralski crystal growth. In International Conference on Parallel Processing and Applied Mathematics (pp. 469-474). Springer, Berlin, Heidelberg.

[6] Raval, N., & Gupta, A. K. (2015). Historic Developments, Current Technologies and Potential of Nanotechnology to Develop Next Generation Solar Cells with Improved Efficiency. International Journal of Renewable Energy Development, 4 (2).

[7] Gupta, M., & Hasan, M. H. (2014). Design of a Large Effective Area Octagonal Photonic Crystal Fiber (Doctoral dissertation, East West University).

[8] Goetzberger, A., & Hebling, C. (2000). Photovoltaic materials, past, present, future. Solar energy materials and solar cells, 62 (1-2), 1-19.

[9] Nusbaumer, H. (2004). Alternative redox systems for the dye-sensitized solar cell.

[10] Meissner, D. (2013). Photovoltaics based on semiconductor powders. Materials and Processes for Energy: Communicating Current Research and Technological Developments.

[11] Fraas, L. M. (2014). History of solar cell development. In Low-Cost Solar Electric Power (pp. 1-12). Springer, Cham.

[12] Petrova-Koch, V. (2009). Milestones of solar conversion and photovoltaics. In High-Efficient Low-Cost Photovoltaics (pp. 1-5). Springer, Berlin, Heidelberg.

[13] 1962: The first telecommunication satellite, Telstar was launched by Bell telephone laboratories

[14] Hegedus, S. S., & Luque, A. (2003). Status, trends, challenges and the bright future of solar electricity from photovoltaics. Handbook of photovoltaic science and engineering, 1-43.

[15] Fraas, L. M. (2014). History of solar cell development. In Low-Cost Solar Electric Power (pp. 1-12). Springer, Cham.

[16] Rosenblum, Louis, et al. “Photovoltaic power systems for rural areas of developing countries.” Solar Cells 1.1 (1979): 65-79.

[17] Jewell, W. T. (1989). Electric utility experience with solar photovoltaic generation. IEEE Transactions on Energy Conversion, 4 (2), 166-171.

[18] Wang, A., Zhao, J., & Green, M. A. (1990). 24% efficient silicon solar cells. Applied physics letters, 57 (6), 602-604.

[19] Imamura, M. S. (1994). Grid-connected PV plants: field experiences in Germany and a pursuit of higher solar energy collection efficiency. Solar energy materials and solar cells, 35, 359-374.

[20] Kumavat, P. P., Sonar, P., & Dalal, D. S. (2017). An overview on basics of organic and dye sensitized solar cells, their mechanism and recent improvements. Renewable and Sustainable Energy Reviews, 78, 1262-1287.

[21] Friedman, D. J., Kurtz, S. R., Bertness, K. A., Kibbler, A. E., Kramer, C., Olson, J. M., & Snyder, J. K. (1995). Accelerated publication 30.2% efficient GaInP/GaAs monolithic two‐terminal tandem concentrator cell. Progress in Photovoltaics: Research and Applications, 3 (1), 47-50.

Both concentrating solar and solar photovoltaics could attract much attention during the energy crisis in the 1970s, triggered by the OPEC embargo in 1973. However, it was not until the early 2000s that solar photovoltaics had an appreciable grid-penetration. Concentrating solar power was the giant in the solar energy industry until the beginning of the 21^st century. Anyhow, it could not maintain its glory all along the line. Solar photovoltaics started an outstanding and progressive journey. They just emerged as a little child and then started to compete with concentrating solar thermal technology, aggressively.

Concentrating solar thermal has been trampling from the very beginning of the 21^st century and notably after 2008. To illustrate, let us take a look at the following chart which explains what happened to the solar energy market in the USA during 2000-2009.

Figure 01: Cumulative solar photovoltaics and concentrating solar thermal capacities in the USA [1]

The chart clearly illustrates that concentrating solar has lost its fame in 2005. Further, it can be noticed that the cumulative solar photovoltaic capacity has been skyrocketing from the beginning of the 21^st century though no significant change has been made by concentrating solar power during the same time period.

Latest trend

Firstly, scalability is one of the secrets that photovoltaic technology dominates in the solar energy industry with a cumulative worldwide capacity of 308 GW whereas the cumulative capacity of concentrating solar thermal was merely 6 GW by 2016, as illustrated by the column chart below [2].

Figure 02: Worldwide cumulative solar photovoltaic and concentrating solar thermal capacities in 2015 & 2016 [2, 3]

As we can see it, the cumulative capacity of solar photovoltaics has grown by 81 GW to reach a capacity of 308 GW by 2016 from 227 GW in 2015. It is, however, interesting to see that the growth of concentrating solar thermal is merely 1.2 GW during the same period of time. The outstanding difference manifests the degree of practical feasibility associated with two technologies.

Above chart implies: Solar photovoltaics is far feasible than concentrating solar thermal. We otherwise would have had a very different column chart with blue colored columns instead of red colored columns and red colored columns instead of blue colored columns!

Overestimations are the most reliable

Enthusiasm is of paramount importance. Nowadays, many countries are keenly encouraging the investors for solar photovoltaics. Especially, China which is always trying to break world records is now breaking even their own records. Previously, they had set a target to reach 105 GW of solar photovoltaic capacity by 2020. However, they could exceed the target readily in 2017 with a capacity of 112.3 GW by July 2017 setting a new target of 213 GW for 2013.

Compare the China’s new target (2013 GW) with the previous target (105 GW). They have doubled their own previous target for 2020. This means the solar photovoltaic capacity has been expanding at an unpredictable rate making the forecasts extremely sterile.

Figure 03: China’s previous and revised targets for solar photovoltaic capacity by 2020

China is now guiding the world towards a Sun-powered society braking their own targets. Estimations are being exceeded making overestimations the most reliable…

Potential in the Sunbelt regions

Today, China, Germany, Japan, USA, Italy, UK, France, India, Australia and Spain are top ten leaders with large solar photovoltaic capacities. We can see that most of these are outside the Sunbelt which receives a much weak amount of solar irradiance compared to the Sunbelt countries. Therefore, these incredible achievements reflected by countries outside the Sunbelt (Germany, France, etc.) clearly have brought to light an unbelievable potential for solar photovoltaics in Sunbelt countries such as India, Pakistan, Bangladesh, China, Myanmar, Sri Lanka, USA (South), etc. as Sunbelt countries receive a great deal of solar radiation throughout the year. Anyhow, most of Sunbelt countries have not yet understood the value of solar energy which can be made a God’s gift if exploited properly.

Through hard work and perseverance, Germany could work its way up to the country with the second largest photovoltaic capacity. Being a country outside the Sunbelt, Germany is an obvious showcase to both Sunbelt and snowy countries like France and the UK for successful adaption of photovoltaic technology. Developing countries are, however, far lagging behind the European countries even though most of the developing countries are located within the Sunbelt. Anyway, a large majority of developing countries located in the Sunbelt like China, India, and Morocco are now increasingly turning towards solar photovoltaic technology.

No one can predict to what extent solar photovoltaics are going to serve the world.

But one evident fact from the recent past…

Solar photovoltaics would keep breaking the pre-set estimations…

Discouraging to predict the cumulative capacity but heavily encouraging to invest in photovoltaics….

References

[1] Devabhaktuni, V., Alam, M., Depuru, S. S. S. R., Green II, R. C., Nims, D., & Near, C. (2013). Solar energy: Trends and enabling technologies. Renewable and Sustainable Energy Reviews, 19, 555-564.

[2] Kumar, V., & Goyal, N. (2018). Comprehensive Study of Different Renewable Energy Resources such as Hydro Energy, Solar Energy and Wind Energy.

[3] Kabir, E., Kumar, P., Kumar, S., Adelodun, A. A., and Kim, K. H. (2018). Solar energy: Potential and future prospects. Renewable and Sustainable Energy Reviews, 82, 894-900.

[4] Mathews, J. A. (2017). China’s Electric Power: Results for first half 2017 demonstrate continuing green shift. Asia-Pacific Journal: Japan Focus, 15 (17).