1. Introduction
The energy associated with greenhouse gas emissions should be mitigated, and according to the Pais Agreement, 187 countries are committed to working on the causes of climate change (UNFCC, 2016). The Technologies of Renewable Energy (TRE) systems can be shared, decarbonising the energy mixture (Rena, 2012) and stated by (Ziegler et al., 2019). The Renewable Energy (RE) is valuable energy obtained from renewable resources that are replenished naturally on the time-frame, (Ellabban et al., 2014). So, it includes carbon-free energy sources such as wind, solar, biomass, tides, waves and geothermal heat (El-Hinnawi and Biswas, 1981) and specified by (Dincer, 2000).
The solar energy is an energy source that is efficient, clean, sustainable; and environmentally friendly (Dincer, 2000) and described by (Sims, 2004). With the growing attention of the world's population in the development of renewable energy, the potential of solar energy has seen an enormous development (Foster et al., 2009).
The feasibility of moving from a conventional power generation system (fossil fuel) to clean, renewable energy for electricity generation in Libya. The contribution of street lighting load represents about 19% of the electricity demand in Libya (Asheibi et al., 2016). The suggestion of alternative by using street lighting system of standalone PV solar-powered Light-Emitting Diode (LED) lighting system and LED lighting system grid-connected solar-powered (Khalil et al., 2017). A study performed by (Aldali and Ahwide, 2013) proposed analysis of installing a 50 MW solar photovoltaic power plant PV-grid connected with a tracking system in Libya. Solar PV modules of 200 W are used in that study due to its high conversion efficiency. A case study of the Al-Jagbob region, a long-term meteorological data parameter, has been collected from the Libyan Renewable Energy Authority, and the consequence proved that the Al-Jagbob region has a high level of yearly solar radiation record. Also, mean daily sunshine hours, the mean long-term daily global radiation, and the average daily wind speed. The results of energy production illustrations that the gross output energy is about 128.5 GWh/year.
The scientific report analysed that the photovoltaic plant's development creates more jobs, reduces pollution, attracts more development in solar energy and introduces new technologies in this area. Furthermore, local firms can design and build most of the necessary components. Based on the 20-year lifespan of the competing plants, the photovoltaic module is much more economical, mostly because it needs no fuel and has lower operational and maintenance costs. Therefore, it's clear that it is the best choice possible for the state (Eljrushi and Zubia, 1995). A study showed the importance of desert and solar energy in Libya as the greatest alternative to conventional fuel. One of the primary challenges with renewable energy is matching renewable energy generation and load patterns. Though, one of the key areas of energy usage, which is usually proportional to the availability of solar sunlight through the day, is the demand for energy for air-conditioning (Mohamed et al., 2013).
The solar photovoltaics (PV) was used in Libya back in the 1970s; the application areas power loads of small remote systems such as rural electrification systems, communication repeaters, cathodic protection for oil pipelines and water pumping (Asheibi et al., 2016). (Nassar and Awidat, 2007) presented the utility of solar PV systems to generate electrical energy in the southern area of Libya. Hence, predicted the reliability of using solar photovoltaics by considering the environmental parameters such as solar radiation intensity, ambient temperature and wind speed.
Libya has a rising need for electricity and uses fossil-fuel generating plants to produce most of its electrical energy (Al-Refai, 2014) and reported by (Al-Refai, 2016). There is a possibility of using the solar radiation potential in the southern part of the country to satisfy this requirement with a source of renewable energy (Alnoosani et al., 2019) and studied by (Bannani et al., 2006). To the best of our knowledge, there are no installations of the bifacial PV modules and concentrating photovoltaics technology in Libya. There is a great potential for solar direct normal irradiance (DNI). The significance of this paper being highlighted the problems of electricity generation in Libya and attempt to suggest an alternative approach. Therefore, this paper investigates the importance of solar PV application in Libya. This study structured as follows: Section 1 summary of introduction; Section 2 represents the situation of electrical energy and its challenges in Libya and the variation of electrical loads. Section 3 analyses the effects of the environmental conditions and challenges such as soiling deposition and environment temperature. Section 4 represents the potential of solar energy in Libya. Section 5 reviews solar PV application in Libya. Section 6 presents the opportunities and possibilities of solar energy availability in Libya. Section 7 presents a future perspective of solar PV projects and large-scale plans, whereas section 8 presents future work and a summary of the conclusions.
2. The situation of electrical energy in Libya and its challenges
2.1. The electrical energy situation in Libya
The Libyan electricity system is administered by the General Electricity Company of Libya (GECOL). The company is state-owned and manages and controls the generation, transmission, distribution and networks systems (Alsuessi, 2015). Hence, the situation puts the (GECOL) in the face of enormous challenges; it is most critical being that it struggles to offer its clients with the desired quantity and quality of electricity (Belgasim et al., 2018).
Energy is one of the most essential and crucial elements of life, growth of human societies and develops economy (Watts, 2013); and reported by (Edenhofer et al., 2011). Libya relies fully on fossil fuels to generate its electricity; hence, the Natural Gas and Oil are the key energy sources (Sorensen, 2010). The power stations in Libya are dependent on light and heavy oil, with a growing dependency on natural gas (Asheibe and Khalil, 2013).
As a consequence of the population increase and with the development of construction projects, the demand for energy in Libya has increased rapidly. Besides, Libya's electricity consumption is typically high, as it is considered one of Africa's big users of power (LUEP, 2015). This is due to many factors, such as cultural rules, practices of social life, and the most key factor is the subsidized electricity tariff. Therefore, in Libya, the energy sector is subsidized, where electricity tariffs are deemed (Almaktar, 2018).
Hence, there is indeed a high gap between the generating price and the tariff cost given to the customer. But, on the other hand, the hybrid renewable energy system implementation intended here is aimed at reducing the cost of generation (Sayah, 2017).
Over a decade, there was a gradual increase in load, which was shown before 2011, but after that period from 2013, the trend changes to rapid increases in load demands (Mohamed et al., 2013). The consumption was about 5.5 GW in 2011 and forecasted exponential growth the load at “2020” to be 9 GW (Belgasim et al., 2018); and specified by (Mohamed et al., 2015). Fig. 1 illustrates the development of electrical computation in the Libyan grid from “2001–2020”.
Fig. 1There was a rapid increase in construction which leads to an increase in the load demand. On the other hand, there is no development in the grid to meet that demand. Also, current power plant units need major maintenance as per schedule after certain working hours. Moreover, due to the fragile security situation and the war, the General Electricity Company of Libya (GECOL) has contracted with the manufacturing companies to perform major overhaul services on the power plants. Hence, unfortunately, no company is willing to send their professional's/engineers to the country to make the major maintenance services to the power generation units.
In Libya, the history of load profile data indicates that throughout the summer months, the maximum power occurs and that the residential sector accounts for the highest share of the demand for electrical energy, which represents 36%. Respectively followed by 23% in others,14% represents the commercial/industrial sector, as seen in Fig. 2 (Dagroum et al., 2014).
Fig. 2The population growth is causing a substantial increase in the demand for electricity in Libya, generating a tremendous need for additional infrastructure development, including power lines and increased power plants. Also, industrial development requires continuous power station operations and greater fuel consumption. That strongly urges the need for Libya state to study, exploiting and the feasibility of renewable energy technology (Mohamed et al., 2013).
2.2. Variation of electrical load in Libya and the challenges
In the current situation of Libyan electrical generation units are frequent power outages, so, that outages sometimes stay many hours. Hence, this deterioration urges the most population to use temporary emergency generators in their houses, to meet the need for electricity. But there is a shortage of fuel and spare parts, and maintenance issues as well; that's why this solution does not resolve the issue. Based on field data collected from Libya, energy consumption is gradually increasing annually.
The Libyan energy providers and government organizations anticipate that electrical power consumption can double by “2015” and reach two and a half through the end of “2020” (Schäfer, 2016). Besides that, electricity load prediction is one of the most critical tasks that ought to be taken into account (Mohamed et al., 2013). The significant source of the challenges for the load management engineering for each electricity generation system (Khalil et al., 2009).
Table 1., tabulated the development of Libyan energy demand; also, gives growing rate from those years, which used to predict the increase in electricity demand in the near-next years. The load prediction model has numerous variables that have political, atmospheric, economic, and demographic characteristics. There is a difference between day and night usage, which is a significant part of residential, industrial, agricultural and public utility loads (Mohamed et al., 2013). It is important to be mention that, the majority of government organizations, academic and educational institutions consumes energy during the day (Schäfer, 2016).
Table 1. Listed the development of Libyan energy demand (Schäfer, 2016).
| Category | “2008″ | “2015″ | “2020″ |
|---|---|---|---|
| Installed capacity (MW) | “6000″ | “8000″ | “20,000″ |
| Electricity Generation (TWh/y) | 29 | 73 | 109 |
Over the years, Libya's electricity consumption is projected to increase dramatically. This will contribute to a substantial need for new power plants to meet with continuing demand progress (Ahmed, 2018). In addition, there is a clear correlation between its load needs and the climate since most of the loads are residential consumption (Mohamed et al., 2015). Consequently, the excessive usage of air conditioning units in summer and heating in the winter causes the load to increase (Rajab et al., 2017).
To some extent, the utilisation of renewable energy technology, such as solar, wind, etc., in power generation, would also lead to a decrease in greenhouse gas emissions. The conservation of Libya's oil and gas reserve is not valuable for Libya but important for the global environment prevention. The electricity system in Libya is subsidized due to the government, which implemented an economic system for more than 40 years. Therefore, at the moment, the implication of this strategy is obvious in the excessive usage of energy by the most Libyan people (Asheibi et al., 2016).
The infrastructure electricity in Libya is suffering from several problems. Also, the current electricity grid system doesn't meet the electricity demands of the agricultural, industrial, residential and commercial sectors. Moreover, the current obstacle for the energy strip is signified in the inadequacy of energy amplitude, which has led to power blackouts in the most district of the country, particularly during the summer season. Therefore, to overcome this barrier and improve the sustainable development of the energy system. This, corresponding with Libya's energy demands for local and international scales, based on that there are several challenges required overcoming. Those challenges are summarised as follows (Sayah, 2017)
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The losses of electricity on the transmission lines due to electricity destitution over long distances.
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The ruin that occurred to the energy infrastructure through the period of the events in “2011”.
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Population growth in the country will lead to a rise in the electricity demand; hence, expansion projects of industrial, construction and agricultural will be activated.
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None managing to perform the schedule planning maintenance to the power station units, and shortage of spare parts due to the civil war.
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The conventional power plants that dependence on fossil fuel (oil and gas), one of the emission emitters to the environment.
3. Environmental challenges of installing solar PV systems
The performance behaviours of a solar PV system significantly depending on environmental conditions, such as cloud cover, soiling, squall lines, etc. Hence, due to its uncontrollable characteristics, grid-connected PV systems can be considered a negative load. Subsequently, the economics perspective would play a major role in assessing the feasibility of the Libyan system's large-scale inclusion of solar PV. Therefore, the positive elements of decreasing CO2 emissions on a global and regional level should be integrated into economic considerations (Hewedy et al., 2017).
3.1. Soiling deposition
The soiling means an accumulation of dust, tiny particles of sand, trees debris, and birds dropping on the surface of PV modules. Based on that causes a shading of the incident sunlight on solar PV modules. The dust accumulation is one of the challenges that faced the solar PV in Libya; thus, the prevalent climate in the country is a desert climate (Mohamed and Hasan, 2012).
The accumulation of soiling or dirt objects on the solar module has significant effects on performance behaviour and conversions efficiency (Gouws and Lukhwareni, 2012) and analysed by (Mostefaoui et al., 2018). Hence, Mohamed and Hasan (2012) performed an experimental study in the southern region that recommended weekly cleaning through the months from January–June, then followed by one a month's cleaning schedule.
One way to mitigate the effects of soiling is by washing the modules. The method of cleaning early in the morning or just before the sunset. It is important to know the period of the windy, sandy storm. Cleaning the device can keep devices getting better and get the optimum benefit with a certain frequency. In a maintenance schedule for all commercial solar installations, the solar cells give and the capability to tackle the issue away from our customers.
The dust and dirt might accumulate on the surface of the solar module, covering some of the illumination and decreasing efficiency (El-Ghonemy, 2012). While conventional dust and debris are washed away during every rainy season, the predicting of device performance is taking into consideration the decrease due to dust accumulation in the summer months (Maghami et al., 2016). Furthermore, the tilt angle of solar photovoltaic modules can also alleviate the effects on dust/sand accumulation (Khodakaram-Tafti and Yaghoubi, 2020). Therefore, it is important to be select an optimum tilt angle (Hammad et al., 2018).
3.2. Environment temperature
Libya's weather is dry, with most regions of the country being a desert, particularly in the south. Like several other countries located on the Mediterranean Sea, the weather in coastal regions is typical of the Mediterranean climate, and Libya's terrain is mainly desert. The environment temperature in Libya is increasing in the summer season, particularly in the southern region.
Temperature dependence is an important parameter in the characterisation of the performance behaviour of solar photovoltaics (Saleh et al., 2013). investigated the effect of ambient temperature on PV module temperature; a comparison was made between ambient and module temperature over four days of the year, 21st of March, June, September and December (Ali et al., 2016). The temperature of the PV module throughout the day demonstrated that because of higher solar radiation levels, warming of the module increased in the afternoon time. The temperature behaviour of the PV modulus was compared and investigated.
For this reason, the areas at which solar PV systems may operate as efficiently as the performance of the standard condition (Nassar and Awidat, 2007). The electrical performance characteristics of solar photovoltaic cells/modules are very sensitive to temperature rises (Ali et al., 2016). The solar PV cells/modules efficiency is designed under a Standard Test Condition STC (cell temperature 25 °C and air mass 1.5) (Mohamed et al., 2021).
The photovoltaic cells/module's operating temperature is characterised by the energy balance between the heat generated by the (PV) module, the heat lost to the surrounding environment and the operating ambient temperature. Therefore, as the environment temperature rise, the result is a change in electrical performance parameters of Jsc,Voc, FF, which consequently leads to a reduction in the PV modules efficiency (Maka and O'Donovan, 2020). The heat generated by the module relies on the module's operating point, the optical properties of the module and solar cells, and the PV module's packing density of the solar cells (Maka and O'Donovan, 2021). One of three methods; conduction, convection, and radiation, the heat released to the environment. The thermal resistance of the photovoltaic module materials, the emissive properties of the (PV) module, and the environmental conditions (especially wind speed) under which the module is installed rely on such loss mechanisms (Honsberg and Bowden, 2014). The partial shading is one of causing a hot-spot phenomenon; it can be detected by frequent inspection of the system devices (Hamed et al., 2018). Furthermore, the half-cut cell technology is another way to alleviate the effects of temperature rise and also shading/soiling effects.
In this study, we consider weather data using the Typical Meteorological Year (TMY), which is a set of meteorological data with data values for every hour in a year for a given geographical location. The temperature variations data used for the (TMY) have been calculated from satellite data. By using the System Advisor Model (SAM) developed by the National renewable energy Laboratory (NREL). The data source from the National Solar Radiation Database (NSRDB) is a database of thousands of weather files, time step every 60 min.
Fig. 3 illustrates the variations of dry bulb temperature of the selected five cities in Libya. Fig. 3 (a) represents Tripoli average monthly temperature, and it is gradually increasing to high values in the summer season. Fig. 3 (b) represents Benghazi average monthly temperature, (d) represents Al-kufra average monthly temperature, whereas (e) Sabha's average monthly temperature. From Fig. 3, an abnormality in the temperature rises, which is almost prevalent during the summer seasons. The average annual temperature varies in the Libyan coastal area from 14.2 °C to 21.0 °C, where the cities of Tripoli and Sirte and Benghazi are located in the coast region. While in-depth south region Sabha and Al-kufra cities, the average annual temperature ranges from 22 to 28 °C.
Fig. 3The dry bulb temperature is the average of monthly temperature that calculated from their corresponding daily values. It is worth noting here the temperature is partly controlled by the “Al-Gibli” which is a dry-hot wind for the south western region, starts from the end of spring and remain there till the summer. Similarly, for the north-western region, cold wind affecting the temperature in the winter (Ageena, 2013).
4. Potential of solar energy in Libya
4.1. Solar radiation
There was a great potential of solar radiation intensity available in entire Libya; thus, it is a geographic location in North Africa. Libya is located in North Africa and bordered by Egypt and Sudan to the east, Tunisia and Algeria to the west, Chad and Niger to the south, and the Mediterranean Sea from the north. Thus, it's Global Positioning System (GPS) coordinates the latitude: 26.3347° N and longitude: 17.2692° E. Moreover, it has long sunny spill in a daily basis and annually. Therefore, in terms of solar energy, it could be argued that the most significant source of renewable energy is solar energy.
Due to Libya's geographic location on the cancer orbit line with exposure to the sun's rays during the year and with long hours throughout the day, solar energy may be considered to be one of the main resources (Bannani et al., 2006). The estimated daily solar average radiation on the horizontal plane is approximately 7.1 kWh/m2/day in the northern coastal area and 8.1 kWh/m2/day in the southern region (Al-Refai, 2014), and described by (Al-Refai, 2016); with an annual average solar greater than “3500” hours (Bannani et al., 2006). The ‘Libyan Renewable Energy Authority’ has estimated that the average solar sunlight hours are approximately “3200” hours/year and that the average solar radiation is 6 kWh/m2/day (Mohamed et al., 2013). Therefore, renewable energy could provide a good complement for meeting peak loads; and this, in turn, may be a reasonable reason to encourage Libya's government to invest in solar projects (Yahya et al., 2020).
Solar energy may provide inexpensive and plentiful energy, in rural and remote areas, for communities where the link to the power grid may not be economical because of their remote physical location from the nearest grid connection point. The rapid growth of small-scale manufacturing decreases the drift from rural to urban areas (Shaaban and Petinrin, 2014). The state receives higher solar radiation, and solar energy is considered as an alternative energy resource (Guwaeder and Ramakumar, 2017b).
The average forecasting for daily/annual solar global horizontal irradiance in entire Libyan areas is described in Fig. 4. The global horizontal irradiance distribution over the period from “1994–2018”, as it has shown the coastal regions (north) have average daily radiation of about 6 kWh/m2, and the average of annual is about “2264 kWh/m2”. In-depth south regions of Libya, the average daily global horizontal irradiance distribution is about 7.1 kWh/m2, although the annual average is about “2556 kWh/m2”.
Fig. 4The forecasting of the protentional distributions of solar PV power in Libya area from “1994–2018” is depicted in Fig. 5. Hence, in the coastal regions (north), the solar photovoltaic systems are estimated to generate power about 5 kWh/kWp daily, and the annual forecasting is about “1826 kWh/kWp”. In-depth south regions of Libya, the daily average solar PV power protentional is greater than 6.5 kWh/kWp, although the annual average is greater than “2045 kWh/kWp”.
Fig. 5A huge quantity of power generation could be generated by the renewable energy sector to cover some, but not all, of the energy demand (Alsuessi, 2015). A high-level plan has been developed to rely on renewable energy and decrease pollution and CO2 emissions in Libya (Hewedy et al., 2017). The most accessible renewable energy sources in Libya are wind and solar. But the wind potential is limited to a certain region; although, the solar potential is available over the entire country. Nevertheless, most renewable energy initiatives and plans have been put on hold by the current political situation in Libya, maybe until the environment has become more comfortable (Mohamed et al., 2016).
The unique location of Libya is characterised by a great simple area, which is an excellent place for the usage of solar energy. Libya is blessed with long sunny hours and is exposed to the sun's rays throughout the year (Al-Refai, 2016). Moreover, the country is rich with abundant and reliable solar energy resources with an estimated average of sunshine of over 300 days per year (Alnoosani et al., 2019).
5. Application of solar PV in Libya
The technology of solar photovoltaic (PV) is one of the clean energies and most appealing choices used to generate electricity. Consequently, the small-scattered standalone photovoltaic systems; also, small/medium-sized, building-integration and grid-connected photovoltaic power systems, represent tremendous promise potentials (Aldali and Ahwide, 2013). Thus, large-scale solar photovoltaic systems might represent an upcoming choice for world energy sources (Aldali, 2012).
The utilisation of solar photovoltaic (PV) has been used for more than four decades. Since “1976” in Libya, the photovoltaic system has been applied in several projects in various sizes and purposes. Its first project implemented was in oil fields, in which the solar photovoltaic device was utilised to supply cathodic protection (CP) systems to prevent the oil pipe-lines from the corrosions. Although the use of PV systems began in “1980” in the field of communication, the first PV system was installed to provide energy to the southern “microwave repeater stations”. Furthermore, in “1983”, the solar PV system began to be used in the agriculture sector; thus, the photovoltaic system was used to feed the water pumps in some farms in the towns of western Libya. At the beginning of 1984, solar water pumping projects were also initiated. The uses of solar photovoltaic systems in the lighting and electrification in the rural was implemented in 2003 (Al-Jadi et al., 2005). Fig. 6 display an example of the application of solar photovoltaic in Libya.
Fig. 6In Libya, the solar PV applications are typically utilised in remote areas, particularly when it is expensive to link such regions to the power system. In contrast to the traditional off-grid energy systems like the diesel generators, these systems demonstrate their viability, due to the expenditure of transporting fuel and the challenge of reaching those locations. However, although power shortages occur in the power grid, the solar PV system with storage will be configured to fulfil the load demand at a given amount of safety (Guwaeder and Ramakumar, 2017a). In addition to other specific methods, the sizing work for PV systems relies on three key solar PV systems sizing techniques known as analytical approaches, numerical, i.e. simulation-based and to other specific methods (Khatib et al., 2013). Therefore, Table 2., listed seven applications of solar photovoltaic systems in Libya.
Table 2. application of solar photovoltaic systems in Libya.
| No. | Applications | Authors | Descriptions | Results and remarks | Refs. |
|---|---|---|---|---|---|
| 1 | PV Power plant | Aladli et al. | Designed of Al-kufra 50 MW very large-scale PV power plant. |
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| 2 | Powering mobile phone stations | Ghozzia and Mahkamov | Modelling of the standalone PV system by using Simulink Matlab model. |
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| 3 | PV-water desalination | Elfaqih | Investigation and design of small-scale standalone photovoltaic system incorporating seawater reverse osmosis plant. |
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| 4 | Solar PV powered LED lighting system | Khalil et al. | Investigates the feasibility study of using street lighting system, standalone solar-powered LED. |
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| 5. | Photovoltaic water pumping. |
Shebani and Iqbal Maka et al. |
Dynamic modelling and analysis of a solar (PV) water pumping. Performance evaluation of the in-situ solar water pumping system. |
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| 6. | Cathodic Protection (CP) Photovoltaic Powered oil pipelines. | Al-Refai | Numerical calculation and simulations of solar photovoltaic powered cathodic protection for underground oil pipelines. |
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| 7 | Standalone photovoltaic SAPV for house electrification | Ben-Naser | The PVSYST software is used here as Powerful tools. |
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This foundation will motivate and encourage people to make a successful investment and participate in the expansion and deployment of new sources of renewable energy. Moreover, this framework provides a strategic plan to develop an economy based on technology and knowledge for all main players (Glaisa et al., 2014). performed a techno-economic study of photovoltaic/wind/diesel/battery for powering Libyan schools was carried out, and the results showed it's feasibility.
As a result of political conflicts, Libya has been facing a tremendous power shortage that has left most hospitals in the darkness. Thus, to operate life-saving medical equipment, medical centres need electricity. The United Nations Development Programme (UNDP) in Libya; recently supported and helps the government in the 15 hospitals in Libya by installing solar photovoltaic systems from “2016–2017” (Hamladji, 2017a) and reported by (Hamladji, 2017b). Fig. 7 illustrating one of the Hospital roofs installations of solar PV systems, where (a) front view, (b) side view.
Fig. 7When the hospitals, operating rooms, medicine stores, maternity wards and laboratories do not have enough electricity, exposures people live to risk. So, that can offer more patients access to primary treatment via a sustainable, renewable and reliable source of energy with the installation of the solar system for health facilities. It has become when they need a quick response, and we have both a fast and a long-term solution with solar systems. Table 3., listed Libyan hospitals that are benefiting from solar PV installation.
Table 3. listed the Libyan hospital that is benefiting from the installation of solar PV (UNDP, 2018).
| Sr.no. | Name of Hospital | District |
|---|---|---|
| 1 | Ali Omar Askar Neuro | Tripoli |
| 2 | Abu-sleem Hospital | Tripoli |
| 3 | Tripoli Heart Centre | Tripoli |
| 4 | Cordoba Centre for Services in Tripoli | Tripoli |
| 5 | Al Gwarsha clinic in Benghazi | Benghazi |
| 6 | Benghazi Al-Kwefia Hospital | Benghazi |
| 7 | Benghazi Dermatology Hospital | Benghazi |
| 8 | Sabha Hospital | Sabha |
| 9 | Kikla Municipality | Kikla |
| 10 | Rujban Hospital | Rujban |
| 11 | Zintan General Hospital | Zintan |
| 12 | Zintan Emergency and Surgery | Zintan |
| 13 | Zintan Obstetrics and Gynecology Hospital | Zintan |
| 14 | Ubari General Hospital | Ubari |
| 15 | Ubari General Hospital – Dialysis | Ubari |
6. Opportunities and possibilities
The potential is huge, and the deployment of solar energy will play a role in achieving renewable energy; contributing to covering the gap in the existing shortage of energy resources that Libya is facing (Sayah, 2017). However, in-depth analysis is required for this study, Libya has a great potential for solar intensity because of long shining hours, and it is located on the sun-belt axis.
To predict annual weather data parameter of five locations in Libya, the Typical Meteorological Year (TMY) is used here; so, a set of meteorological data with data values for every hour in a year for a given geographical location. The solar radiation data used for the TMY have been calculated from satellite data. By utilising a System Advisor Model (SAM) in which developed by the National renewable energy Laboratory (NREL). The data source is from the National Solar Radiation Database (NSRDB), a database of thousands of weather files, and time step every 60 min.
Fig. 8 illustrates Tripoli incident solar radiation, (a) graph represents the DNI values in which fluctuated widely, and the yearly average was approximately 900 W/m2. Fig. 8 (b) represents monthly DHI fluctuation with an average of about 350 W/m2 from October–March and 450 W/m2 from April to September, during the spring and summer seasons. The average albedo variation from December to January is about 0.13, while there is a fluctuation from February to November.
Fig. 8Fig. 9 displays Sirte incident solar radiation, (a) graph represents the DNI values in which the values fluctuated widely with the yearly average was approximately “1000 W/m2”. Fig. 9 (b) represents monthly DHI fluctuation with an average of about 300 W/m2 from September–March and average of about 400 W/m2 from April to August. The average albedo variation from March to November is about 0.2, while from December to February is approximately 0.9.
Fig. 9Fig. 10 illustrates Benghazi incident solar radiation in Benghazi city, (a) graph represents the DNI values that fluctuated widely, and the yearly average was approximately 900 W/m2. Fig. 10 (b) represents monthly DHI fluctuation with an average of about 200 W/m2 from October–March; while the average of 400 W/m2 from April to September. The albedo average variation from April to November is about 0.15, while from December to March is approximately 0.8.
Fig. 10Fig. 11 illustrates Al-kufra incident solar radiation, (a) graph represents the DNI values that fluctuated widely, and the yearly average was approximately “1000 W/m2”. Fig. 11 (b) represents monthly DHI fluctuation with an average of about 400 W/m2 from April–August; while the average of 250 W/m2 from September to March. The albedo average variation from April to December is about 0.15, while from January to March is approximately 0.8.
Fig. 11Fig. 12 illustrates Sabha's incident solar radiation, (a) represents the DNI values that fluctuated widely with a yearly average was approximately 900 W/m2. Fig. 12 (b) represents monthly DHI fluctuation with an average of about 400 W/m2 from April–August; while the average of 200 W/m2 from September to March. The albedo average variation from April to November is about 0.2, while from December to March is approximately 0.9.
Fig. 12Albedo can be defined as the amount of the diffuse reflection of solar radiation from the whole solar radiation. The albedo is largely dependent on the incident angle and the earth's surface characteristics. The electric energy output of the solar photovoltaic devices can be affected by albedo. For instance, the variations in the spectrally weighted albedo of solar photovoltaic technology demonstrate the effects of a spectrally sensitive albedo. Compared to conventional spectral-integrated albedo predictions, the foundation is based on crystalline silicon (c-Si) and hydrogenated amorphous silicon (a-Si:H) (Andrews and Pearce, 2013). Analysis of the influence of albedo on the efficiency of seven photovoltaic materials covering common triple modules of photovoltaic devices: commercial flat rooftops, pitched-roof residential applications and industrial “solar farms” (Brennan et al., 2014). It is important to mention that albedo is a key factor in the performance characterisation of solar bifacial systems.
The solar radiation is defined as the “solar energy received on the Earth's surface, which is the sum of Direct Normal Irradiance (DNI) and diffused radiation after scattering in the atmosphere” (Kim, 2015). Although the rays pass through the atmosphere longer, due to the increasing atmospheric absorption and possibility of scattering, the solar radiation attenuates more (Kim, 2015); and specified by (Maka and O'Donovan, 2019). The efficiency of solar photovoltaic cells relies on the amount of radiation and the solar spectrum. The sun emits electromagnetic radiation with a continuous spectrum due to the continuous nuclear reaction, which matches blackbody radiation at a temperature of about “5250 °C”. The air mass (AM) is defined as a “measure of how absorption in the atmosphere affects the spectral content and intensity of the solar radiation reaching the earth's surface”. The air mass value is given by this relationship (1):where θ is the angle of incidence (zenith angle) and is recognised as the angle between the direction of the sun and the zenith. A more attenuation of irradiance, especially in the Ultraviolet (UV) region of the spectrum, characterises the higher air mass. Since moving through the atmosphere, the terrestrial spectrum is the light that enters the earth's surface. The air mass zero (AM = 0) indicates that the sun's spectrum is outside of the atmosphere of the earth. While the air mass global is a direct incident compound of earth irradiance and diffusion compounds. Fig. 13 shows a different air mass of solar radiation. The earth receives two types of solar radiation: direct (beam), or sometimes called Direct Normal Irradiance (DNI) and Diffusion Horizontal Irradiance (DHI). Therefore, the global radiation is the sum of two types on the earth which are given by:
Fig. 13The solar irradiance including in the sun's spectrum is a function of wavelength light, the basic reference spectra are often used for solar cell characterisation, thus the distribution of the sunlight spectrum that observed on Earth planet. The changes in air mass have significant effects on the solar spectrum. It is described as a ratio between the optical path length when the sun is at the zenith and the optical path length. The variance in air mass over a day is shown in Fig. 14, which results in a substantial variation in the spectral distribution of DNI on the earth's surface. The solar intensity decreases as air mass rises from 1 to 10 D, and the wavelengths become shorter, then resulting in a change in the direct spectrum (Algora and Rey-Stolle, 2016).
Fig. 14The approach has been selected for an investigation to study the movement of solar radiation, sunlight period over Libya. The selection of these five cities is important because of their different geographical location, coast and desert environment. Table 4., listed geographic coordinate and locations in Libya.
Table 4. listed the geographic coordinate of the selected city of Libya.
| No. | City | Longitude | longitude | Location in the country | Elevation from sea level |
|---|---|---|---|---|---|
| 1 | Tripoli | 32.8 | 13.1 | North - West | 21 m |
| 2 | Sirte | 31.2 | 16.58 | North - centre | 24 m |
| 3 | Benghazi | 32.1 | 20.06 | North - east | 3 m |
| 4 | Al-kufra | 24.19 | 23.29 | South - east | – |
| 5 | Sabha | 27.04 | 14.43 | South - west | 420 m |
The selected five cities in this study have been distinguished as the following: Tripoli city is the country's capital city with a high population. Further to the aforementioned characteristic of solar opportunity, it can connect the PV plants to the national electrical grid. Benghazi city is the second-largest city in the country in terms of population; it is located in the East region and can connect to the national electrical grid. Sirte city is the link between the three regions, east, west and south. Sabha city is located in the west-south region. Al-Kufra city is located in the east-south region. Sirte, Sabha and Al-kufra have large open lands and can be connected to the national electrical grid.
Solar sun path charts were generated using the software program called the Solar Radiation Monitoring Laboratory (SRML), which was developed by the University of Oregon USA (USRML, 2020). This diagram represents the tracking of the sun moving over the year. Also, describes the sun path in terms of azimuth angle, elevation and show the day-time hours.
It is important to mention that the azimuth angle specifies the direction of the sun in the horizontal plane from a certain place, it's a variable scale from 0° to 360°, with both directions East and West. Also, the elevation angle measures the height of the sun in the sky from the horizon; it's a variable scale from 0° to 90° (USRML, 2020). The solar resource is dependent on the solar radiation, which varies from one location to another depending on the coordinates of the area (i.e., time zone, latitude and longitude).
The sun path in Tripoli city on 11th of December shows that the azimuth angle varies from about 115° east to 245° west and the sunshine hours from 7 a.m. to 5 p.m. The height of the sun in the sky was aligning at azimuth angle 180° and local time 12 p.m. versus solar elevation of 34°, while on 7th of June, the sunshine hours varies from 5 a.m. to 7 p.m. The azimuth angle was variable, the movement angle from about 62° east to 295° west, the higher sun in the sky in June and the solar elevation was 80° versus azimuth 180° during the noontime 12 p.m. As we move from December to June; the solar elevation and daily sunlight increases. Fig. 15 illustrates the sun path of Tripoli city at a different time of the year.
Fig. 15Fig. 16 shows the sun path of the Sirte city at a different time of the year. The sun path of Sirte city at 11th of December the azimuth angle was variable from approximately 115° east to 245° west and the sunshine hours from 7 a.m. to 5 p.m. The height of the sun in the sky was aligning at azimuth angle 180° and local time 12 p.m. versus solar elevation of 36°, while on 7th of June, sunshine hours is from 5 a.m. to 7 p.m. The azimuth angle was variable, the movement angle from about 62° East to 295° West, the higher sun in the sky in June and the solar elevation was 82° versus azimuth 180° during the noontime 12 p.m. As we move from December to June; the solar elevation and daily sunlight increases.
Fig. 16Fig. 17 display the sun path of Benghazi city at a different time of the year. The sun path of Benghazi city on 11th of December, the azimuth angle varies from about 115° East to 242° west and the sunshine hours varies from 7 a.m. to 5 p.m. The height of the sun in the sky was aligning at azimuth angle 180° and local time 12 p.m. versus solar elevation of 35°, while on 7th of June, the sunshine hours varies from approximately 5 a.m. - 7 p.m. The azimuth angle is variable, the movement angle from about 62° east to 295° west, the higher sun in the sky in June and the solar elevation was 80° versus azimuth angle 180° during the noontime 12 p.m. As we move from December to June; the solar elevation and daily sunlight increases.
Fig. 17Fig. 18 illustrates the sun path of Al-kufra city at a different time of the year. The sun path of Al-kufra city on 11th of December, the azimuth angle varies from about 115° east to 245° west and the sunshine hours from approximately 6:30 a.m. - 5:30 p.m. The height of the sun in the sky was aligning at azimuth angle 180° and local time 12 p.m. versus solar elevation of 32°, while on 7th of June, the sunshine hours varies from approximately 5 a.m. - 7 p.m. The azimuth angle was variable, the movement angle from about 65° east to 295° west, the higher sun in the sky in June and the solar elevation was 80° versus azimuth 180° during 12 p.m. As we move from December to June; the solar elevation and daily sunlight increases.