Solar Energy Discussion
Table of Contents 1. Introduction 2 2. Solar Energy 3 2.1 Photovoltaic Solar Energy (PV) 4 2.2 Concentrated Solar Power (CSP) 5 3. Mohammed bin Rashid Al Maktoum (MBR) Solar Park 8 3.1 Phase 1: (13MW using photovoltaic solar panels) 8 3.2 2nd Phase (200MW using photovoltaic solar panels) 9 3.3 Third Phase (800MW using photovoltaic solar panels) 9 3.4 Fourth Phase (950MW of CSP and PV) 9 3.5 Fifth Phase (900MW using photovoltaic solar panels) 9 4. Conclusion 10 5. References 11

Table of Figures

Fig 1 . information summary of Mohammed bin Rashid Al Maktoum (MBR) Solar Park Al Dahal up to phase 5 3

Fig 2 P-n junction representation (Aqachmar Z, 2019) 4

Fig 3 Types of solar cells (Amin N, 2017) 5

Fig 4 The frequently accepted CSP systems are classified according to their reflector geometry. Sun radiation is represented by yellow arrows, solar receivers are represented by orange structures, solar reflectors are represented by blue structures, and the rotation axis of reflectors is represented by brown arrows with dashed lines. (Zhang H, 2013) 6

Fig 5 Main characteristics of CSP plants according to He YL, 2020. 7

Fig 6 Scheme for CSP gas turbine power plant 8

Fig 7 Project execution breakdown in MBR (data from DEWA; (www.dewa.gov.ae), accessed October 2021. (Anon., 2021) 10

1. Introduction
The economy of the world is increasingly needy on fossil fuels to meet ever-increasing energy demands, making them the dominant source of greenhouse gas (GHG) emissions. Energy mix carbon content is expected to account for 68 percent of GHG emissions, with coal and other fossil fuels accounting for the remaining 32%. Energy use is strongly linked to CO2 emissions. (International Energy Agency Staff, 2017). Due to rapid industrialization and economic growth, the depletion of conventional fuels is insisting the on search for ecofriendly and sustainable alternative energy sources. The UN Assembly established the Sustainable Development Goals (SDGs) to support a sustainable future for everyone. The aims were set in 2015, and it is expected that they would be implemented on a large basis by 2030 (T. Ha ?k, 2016). These goals are aimed to guarantee improved future for the earth.

Renewable energy development, in relation to the SDGs, enables for energy safety in transportation, the environment, the economy, mechanical work, industry, and construction. Renewable energies such as wind, tidal, geothermal, hydro, solar, and biomass enable energy requirement while also facilitating community development and environmental protection on a worldwide scale (M.S. Salvarli, 2020). On a national and emirate level, the UAE has dedicated to implementing worldwide climate change agreements and has developed impressive renewable energy plans. Here, solar energy implementation is producing power and thermal output at a high rate to meet the energy demand of a population of about 10 million people, up from 1 million in 1980. (M.Pagliaro, 2019) The International Renewable Energy Agency (IRENA) relocated to Abu Dhabi in 2015. Similarly, the world’s largest single-site solar plant, with a nominal power of 1.17 GW, was commissioned in 2019. Due to technical innovation and expansion, the UAE can rely on solar photovoltaics (PV) energy to fulfill most of its future electricity needs without building more fossil fuel stations. With this goal in mind, the UAE launched the Mohammed bin Rashid Al Maktoum (MBR) Solar Park near Seih Al Dahal, Dubai. The Dubai Electricity and Water Authority oversees a 5 GW PV and CSP project for over 50 billion AED ($ 13.6 billion), which is controlled by the Dubai Electricity and Water Authority (DEWA). When completed in 2030, the project will occupy 44 km2, making it the world’s largest single-site solar park. The levelized cost of electricity (LCOE) for a 250 MW solar PV project is $2.4 cents per kilowatt-hour (kWh), while a 700 MW CSP plant costs $7.3 cents per kWh [35–39]. The Mohammed bin Rashid Al Maktoum Solar Park project will help the UAE achieve its SDGs, its Energy Strategy 2050, and its Renewable Resources Policy. (Ahmed Elrahmani, 2021). Fig 1 Provides a summary of information. (Anon., 2021)

page3image27517264

Fig 1. information summary of Mohammed bin Rashid Al Maktoum (MBR) Solar Park Al Dahal up to phase 5

2. Solar Energy
The solar energy that falls on Earth every day has the ability to meet the entire planet’s energy demand in theory. Different methods, such as solar thermal (concentrated and non-concentrated) and photovoltaic (PV) approaches, can be used to harness the solar irradiance obtained from the sun’s rays. Each technique collects sunlight photons and turns them to various end products. Photovoltaic systems, for example, transform photons into electrons to generate electricity, whereas solar thermal systems capture photons and convert their energy into heat. This heat is utilized to heat a working fluid, which may then be collected and used to heat space and water. One of the highest solar optical efficiencies obtained utilizing nanofluids was 86.2 percent. Furthermore, the efficiency of PV panels is typically around 15–20 percent. More on photovoltaic and concentrated solar power (CSP) will be discussed below (N. Khordehgah, 2019). Below we will discuss more on PV’s and CSP’s.

2.1 Photovoltaic Solar Energy (PV)
The photovoltaic effect is the technique that allows solar irradiation to be directly converted into an electrical current. The process occurs inside solar cells, which are made up of two types of semiconductors: n-type (negative type) and p-type (positive type) (positive type). A p-n junction is formed by this arrangement. As the holes migrate to the n-side and the electrons migrate to the p-side, an electrical field is formed in this p-n junction, as seen in fig 2.

page6image27024912

Fig 2 P-n junction representation (Aqachmar Z, 2019)

Photons, or little bundles of energy or electromagnetic radiation, make up sunlight. If the light’s wavelength is compatible with the solar cell, the photons’ energy is transferred to the solar cell’s electrons. As a result, these electrons transition from the “valence band” to the “conduction band,” leaving “holes” in the “valence band.” As a result, an electron-hole pair forms.

The p-n junction can be manufactured out of a variety of materials, all of which are improving all the time. As a result, solar cells have progressed from the first to the fourth generation. Crystalline silicon cells make up the first generation of solar cells. CdTe cells, Amorphous Silicon cells, and CIGS cells make up the second generation, commonly known as thin-film silicon cells. As shown in fig 3, dye-sensitized solar cells (DSSC) and multiple junction solar cells from groups III-V are among the third-generation cells. Due to different absorption capabilities of different junctions multiple junctions are used (King RR, 2007).

page7image26974720

Fig 3 Types of solar cells (Amin N, 2017)

2.2 Concentrated Solar Power (CSP)
Global radiation is the amount of sunlight that reaches the Earth. Solar radiation is divided into two types: direct and diffuse. The most essential component of solar concentrating energy generation is direct normal irradiance (DNI), which accounts for the amount of solar irradiance that reaches a normal or perpendicular area. As a result, the ideal sites on Earth for CSP generation are those with higher DNIs, such as regions between 15 and 40 degrees north and south latitudes, as well as places with greater elevations, which is why UAE is ideal for using CSP.

The operating principle of concentrated (or concentrating) solar power is relatively simple: direct solar radiation is focused to obtain high temperature (usually between 500 and 1000 degrees Celsius) thermal energy, which is then converted into electrical energy. Despite the fact that diverse arrangements exist, CSP systems are essentially made up of the same elements:

• A solar reflector (or a set of reflectors) is a device that collects and concentrates sunlight.

• A solar receiver, which concentrates and absorbs sun radiation.

• A power conversion system that converts focused solar energy to mechanical energy.

• An electric generator that converts mechanical energy into electrical energy. (Gauché P, 2017)

The four main types of reflectors can be found. Fig 4.

The major characteristics of previous and future generations of CSP power plants are clearly summarized in Fig 5 (He YL, 2020)

page3image27268384

Fig 4The frequently accepted CSP systems are classified according to their reflector geometry. Sun radiation is represented by yellow arrows, solar receivers are represented by orange structures, solar reflectors are represented by blue structures, and the rotation axis of reflectors is represented by brown arrows with dashed lines. (Zhang H, 2013)

page3image27266512

Fig 5 Main characteristics of CSP plants according to He YL, 2020.

Scheme for an CSP gas turbine power plant with thermal storage subsystems. The main subsystems are depicted, including the solar field, receiver, heat engine (in this case, the Brayton cycle), and TES subsystems in figure 6 such as:

· Heliostat fields

· Solar receivers

· Thermodynamic cycles and working fluids

· Thermal energy storage and hybridization

· Subsystem’s integration and overall plant optimization (Angel G.Fernándezac, 2019)

page8image27620560

Fig 6 Scheme for CSP gas turbine power plant

.

3. Mohammed bin Rashid Al Maktoum (MBR) Solar Park
HH Sheikh Mohammed Bin Rashid Al Maktoum announced the launch of the MBR solar park in January 2012.

3.1 Phase 1: (13MW using photovoltaic solar panels)
On October 22nd, in 2013, the 13MW first phase which comprises of roughly 152,000 solar cells coupled to 13 transformers in inverter buildings went live. The output is converted to 33 kV and produces about 28 million kilowatt-hours (kWh) of power each year. The first phase reduces carbon emissions upto 15,000 tones per year.

3.2 2nd Phase (200MW using photovoltaic solar panels)
The solar park’s second phase, with a capacity of 200 megawatts, supplys clean electricity to 50,000 residents in the Emirate, reducing carbon emissions by 214,000 tonnes per year. This phase witnessed 2.3 million PV solar panels placed across a 4.5 km2 region. The lowest bid (USD 5.6 cents per kWh) for the second place was secured by DEWA and broke a World record at the time of the tender.

3.3 Third Phase (800MW PV solar panels)
The first project in the third phase of the solar park is a first of its kind in the North Africa and Middle East that combines tilting panels that were equipped with sun-tracking technology to maximize output and had a production capacity of 200MW which was enough power to provide for around 60,000 homes. On a total area of 4.48 km2, the project uses 806,992 PV polycrystalline panels.

3.4 Fourth Phase (950MW CSP and PV)
The fourth phase will generate clean energy using three technologies: a parabolic basin complex producing 600MW, a concentrated solar tower producing 100MW, and PV panels producing upto 250MW.

3.5 Fifth Phase (900MW PV panels)
A Request for Qualification (RFQ) was published by DEWA for developers to construct and run the MBR Solar Park’s fifth phase, which has a capacity of 900MW. PV solar panels based on the IPP concept will be used in this phase. Starting in Q2 of 2021, it will be commissioned in phases. (Khaled Obaideen, 2021), (Anon., 2021)

Table Description automatically generated

Fig 7 Project implementation breakdown in MBR (data from DEWA; (www.dewa.gov.ae)

4. Conclusion
The Mohammed Bin Rashid Al Maktoum (MBR) Solar Park is an excellent illustration of large-scale solar projects that help to achieve long-term goals. The reduction of 6.5M tonnes of CO2 equivalent, resulting in a combined power plant capacity of 5000 MW by 2030. It provides power at a levelized cost as low as 2.4 cents per kWh. Enabling the equivalent of 320,000 homes to be powered

References International Energy Agency Staff, 2017. CO2 emissions from fuel combustion.. s.l., International Energy Agency (IEA). T. Ha ?k, S. J. ?. B. M., 2016. Sustainable development goals: a need for relevant indicators. Ecological Indicators, Volume 60, pp. 565-573. M.S. Salvarli, H. S., 2020. Future trends in renewable energy and enabling technologies. s.l.:s.n. M.Pagliaro, 2019. Preparing for the future: solar energy and bioeconomy in the United Arab Emirates, s.l.: Energy Science & Engineering. Ahmed Elrahmani, J. H. E., 2021. Status of renewable energy in the GCC region and future opportunities. Current Opinion in Chemical Engineering, Volume 31. Anon., 2021. [Online] Available at: http://www.dewa.gov.ae N. Khordehgah, V. G. S. L. H. J., 2019. Computational study and experimental validation of a solar photovoltaics and thermal technology. Renew. Energy, Volume 143, p. 1348–1356. Aqachmar Z, A. A. J. A. G. B. K. T., 2019. Parabolic trough solar thermal power plant Noor I in Morocco.. Energy , p. 178. King RR, e. a., 2007. 40% efficient metamorphic GaInPGaInAsGe multijunction solar cells. Appl Phys Lett, Volume 90. He YL, Q. Y. W. K. Y. F. W. W. L. M. G. J., 2020. Perspective of concentrating solar power. Energy, Issue 198. Amin N, A. S. S. C. P. R. K. I. H. M. A. M., 2017. Solar photovoltaic technologies: from inception toward the most reliable energy resource. Encycl. Sustain. Techno. Zhang H, B. J. D. J. C. G., 2013. Concentrated solar power plants: review and design methodology. Renewable Sustainable Energy, Volume 22, p. 466–81.. Gauché P, R. J. M. M. L. W. v. B. T. B. A., 2017. System value and progress of CSP. Solar Energy, Volume 152, pp. 106-39. Angel G.Fernándezac, G.-V. J. O. E., 2019. Mainstreaming commercial CSP systems: A technology review. Renewable Energy, Volume 140, pp. 152-176. Khaled Obaideen, M. N. A. A. H. A., 2021. On the contribution of solar energy to sustainable developments goals: Case study on Mohammed bin Rashid Al Maktoum Solar Park. International Journal of Thermofluids, Volume 12. Anon., 2021. [Online] Available at: https://www.dewa.gov.ae/en/about-us/media-publications/latest-news/2019/03/mohammed-bin-rashid-al-maktoum-solar-park Anon., 2021. [Online] Available at: www.dewa.gov.ae