Solar Energy Potential and Feasibility Study of a 10MW Grid-connected Solar Plant in Libya

Libya is currently interested in utilizing renewable energy technologies to reduce the energy dependence on oil reserves and Greenhouse Gas (GHG) emissions. The objective of this study is to investigate the feasibility of a 10MW gridconnected PV power plant in Libya. NASA data are used to analyze the global horizontal irradiation, direct normal irradiation, and air temperature of 22 selected locations in Libya and to evaluate the potential of solar energy. RETScreen software is used to estimate the energy production, GHG emissions, and financial parameters for the 22 locations. Based on the solar atlas map, it is noticed that the highest global horizontal irradiation is in the southern part of Libya, which ranged from 2100 to 2500kWh/m. These results indicate that Libya has a huge solar energy potential that can be used to generate electricity. Moreover, based on techno-economic results, it is observed that the highest electricity generation of 22067.13MWh is recorded at Al Kufrah and the lowest at Al Jabal al Akhdar with a value of 17891.38MWh. Furthermore, Al Kufrah and Murzuq are the best locations for the future installation of PV power plants from annual energy and the economic parameters point of view. The maximum value of power that can be generated by the plant was estimated to be 22.06GW. Keywords-Libya; NASA data; solar energy potential; RETScreen; techno-economic analysis


INTRODUCTION
Energy is an indispensable need, which was met with the consumption of conventional fossil fuels until quite recently. However, the use of fossil fuels has polluted the environment and contributed to the climate change due to Greenhouse Gas (GHG) emissions [1]. The environmental problems resulting from the increasing fossil fuel consumption encouraged researchers to investigate alternative sources of energy that would be able to generate energy while protecting the environment [2][3][4]. Solar energy has become an important alternative source of energy because it is clean, cost-effective, and readily available. Solar energy can be converted to electricity by Photo Voltaic (PV) modules. The utilizing of PV systems has met the electricity demand in many countries. Many studies investigated the potential for solar energy to generate power in various countries. For example, authors in [5] assessed the feasibility analysis of a 6MW grid-connected PV power plant in six states in Nigeria. Authors in [6] evaluated the technical viability of 1MW grid-connected at the Pekan Campus and Gambang of UMP in Peninsular Malaysia by using PVGIS and PVWatt software. The author in [7] analyzed the feasibility of 1MW grid-connected PV power plant in Cyprus. The results indicated that the capital expenditure of the PV Park is a critical parameter for the viability of the project, in the case where no feed-in tariff is available. Authors in [8] evaluated the potential of developing 5MW gird-connected PV power plants in eight selected cities in the southern coast of Iran using RETScreen software. The results showed that the southern coast of Iran has a huge potential and presents actual market opportunities for investors to develop grid-connected PV projects. Authors in [9] assessed the performance of a 6.4kW grid-connected PV system for household buildings in three regions in Northern Cyprus using simulation software (PVGIS, PV*SOL, and PVWatts). The results showed that solar PV power was a feasible solution for supplying power and reducing the volume of CO 2 emissions. Authors in [10] presented the feasibility of 10MW gridconnected PV plants at 44 sites in Saudi Arabia. The author in [11] studied the feasibility of a PV grid-tied energy system in Jos, Nigeria by using HOMER. The results showed that the system could produce energy of 331.536GWh/year with a capacity factor of 40.4% from solar energy.

A. Renewable Energy Potential in Libya
Libya is now experiencing an energy crisis because of the power cuts that persist for seven years without proven solutions. The electricity service is worsening in Libya. Because of Libya's ongoing civil war, the country has faced a chronic power shortage, and various power plants have been damaged, which has caused a reduction in generation capacity in most populated areas. The Libyan electricity sector depends on a public network linking each power station to provide energy demand to all regions of Libya. The total produced electrical energy in generation stations during 2012 reached 33,980GWh. In 2017, the General Electricity Company of Libya (GECOL) stated that the available products for the network were 4,900MW, while the demand reached 6,500 MW, with a deficit of 130MW in the east and 1,470MW in the west. As a result, the power outage crisis has increased in most of the regions in Libya, i.e. the western region has five to eight hours of blackouts per day whereas the eastern region has 1 to 4 hours of blackouts per day. According to the GECOL statistics, the peak load was 7000MW in 2016. The electricity of Libya is nationalized under the control of the Ministry of Energy. The power plants in Libya are thermal power plants.
There are several power plants in Libya, the most important of which are West of Tripoli (600MW), East of Tripoli (1400MW), Misrata (600MW) and Tobruk (740MW). Also, GECOL stated that it is expected that the maximum load will increase to 10,795MW by 2020, then to 14,834MW by 2030 and 21,669MW by 2050. These estimates are based on an optimistic assumption of the recovery of the Libyan economy, and the increase in demand from the industry and energy sector in particular. Therefore, it can be concluded that the amount of CO 2 and greenhouse gas emissions released will rise as a result of increasing energy consumption. Additionally, the electricity consumption demand in Libya will increase in the long term [12], which indicates that the amount of fossil fuels used for electricity production will increase in the future. Therefore, alternative energy sources, such as wind or solar energy could be the best solution to reduce fossil fuel demand and CO 2 emissions in the country.
Libya is a country rich in renewable energy sources, particularly solar energy, as the annual average solar radiation of the horizontal surface ranges from 5.5kWh/m 2 in the coastal strip regions to 7.0kWh/m 2 in the southern regions [13]. Numerous studies have investigated the potential of renewable energy, especially solar energy, in Libya. Authors in [14] investigated the current utilization and the future of renewable energy in Libya by conducting interviews with managers, consultants, and decision-makers from different government organizations. The results demonstrated that renewable energy could be the solution to cover some of the energy demand in the country. Authors in [15] examined the potential use of renewable energy sources for improving the current and future energy situation in Libya. The results indicated that renewable energy systems could produce energy and achieve cost-saving and reduce CO 2 emissions. Authors in [16] investigated the feasibility of replacing the grid-connected HPS-lamp street lighting system with a solar-powered LED street lighting system for a 4km road in Libya. The results indicated that the stand-alone solar-powered LED lighting system reduces CO 2 emissions, saves fuel, and is economically feasible. Authors in [17] proposed photovoltaic-solar water heating and photovoltaic-photovoltaic/thermal systems for replacing the electrical heater and reducing the peak load demand in Libyan electric grid for households. Authors in [18] evaluated the feasibility of a 14MW PV plant in Houn city, Libya. The results showed that it is economically feasible and sustainable. Authors in [19] assessed the mean monthly solar radiation and sunlight duration to analyze the characteristics of radiation and duration sun rays over Tripoli in Libya. They concluded that solar energy can be considered as a major source of renewable energy in Libya and there is a need to attract investors to renewable energy technology by strengthening the existing infrastructure and laws. Moreover, according to [20], solar power will definitely help to solve the electricity supply problem. Authors in [21] provided an overview of the future of renewable energy in terms of solar and wind energy utilization in Libya. The results showed that Libya has a huge renewable energy potential especially solar and wind, which could be used for various purposes such as electricity generation, communication systems, and mechanical activities. Authors in [22] developed a 50MW PVsolar plant in Al-Kufra, Libya. The results indicated that the energy output was found to be 114GWh/year with a payback time of 2.7 years. In addition, Libyan Minister of Electricity stated that Libya intends to build a solar power station to reduce by one-fifth its electricity needs from fossil fuels [23]. Besides, according to a Member of the Board of Directors of the General Electricity Company in southern Libya, the Libyan government aims to construct a 100MW PV system to solve the electricity problem in Southern Libyan cities [24]. Moreover, according to the Vision of the Renewable Energies and Environment (REEO), the desert renewable energy project is one of the most promising projects in the world, which aims to supply Europe with energy extracted from the solar irradiation in North Africa, mainly Libya, and Middle East. The project can produce 250GW per year, thus preventing the emission of 150,000 tons of carbon dioxide.
In summary, most of the researchers investigated the potential of solar in different parts of Libya. They found that Libya has a great potential for harnessing solar energy, which could be used to generate electricity. Besides, the studies indicated that electricity generated from solar energy could help reducing the electricity sector's emissions and fossil fuel consumption. However, none of these studies analyzed the solar energy potential to examine the best location for the future installation of a PV system in Libya. In addition, none of these papers assessed the sustainability of a 10MW gridconnected PV plant in a suitable location in Libya using RETScreen software, which is a vital tool in project decision making where the uncertainty of any project is analyzed by predicting the future return of the renewable energy project for sustainability.

B. Scope of the Study
The literature review reveals a clear lack of evaluation of solar potential in different locations in Libya in order to examine the best location for the future installation of a PV system. Furthermore, there is a clear lack of exploring the potential of a 10MW grid-connected solar PV system generation. As mentioned above, according to GECOL, it is expected for the maximum load to increase to 10,795, 14,834, and 21,669MW by 2020, 2030, and 2050 respectively. Therefore, the primary goal of this study is to draw a solar energy roadmap that aims to decrease the electricity consumption generated by diesel fuel between 30% and 50% by 2030 when the excepted load will reach 14,834MW. Besides, this paper aims to greatly reduce the GHG emissions of the country. Therefore, the potential of exploiting solar energy in 22 regions in Libya is evaluated. Moreover, this study provides technical, environmental, and economic aspects of the 10MW grid-connected PV system for the regions in order to provide solutions to accommodate the increasing energy demand and to improve living quality in urban areas due to the rapid urbanization of the region. In addition, the production of electricity using solar systems can protect the environment. For this purpose, RETScreen Expert software was utilized to validate the techno-economic 10MW gridconnected solar PV system in the regions.

A. Locations
In this study, 22 regions located in different parts of Libya were chosen as case studies. Information for the geographical locations of the selected cities is listed in Table I.

B. Design of the PV Power System
According to [25], the parameters that are considered of most importance in designing a PV solar plant are: • Power generating factor (PGE): • Solar PV energy required (SPVER): • PV module sizing: • Inverter sizing: where ‫ܴܧܲ‬ is Peak Energy Requirement, ‫ܵܮܧ‬ is energy lost in the system and the factor safety is 1.3 [25].

C. PV Plant Layout
Fifty hectares of land are usually needed in order to install a 10MW solar PV plant. For the proposed PV system, Canadian Solar mono-Si -CS6X-300M with an output power rating of 300W has been considered due to its high efficiency. To build the 10MW grid-connected PV plant in the chosen location, 33500 of the selected modules are required, as calculated with (5). Furthermore, the inverter size is estimated as 13MW. Fourteen units of central inverters of Sunny Central 850CP XT were utilized. Each selected inverter has a capacity of 954kW. The total capacity of 13.356MW was used for the proposed PV system to convert DC into AC power. The grid-connected PV system configuration is shown in Figure 1. Components of the grid-connected solar plant.

D. PV Solar Panels
The solar panels, composed of a number of solar cells, are used to change the sunlight into direct current using semiconducting materials. In general, when the solar radiation falls on the solar cell, the anti-reflective layer effectively traps the incident light by enhancing its transition to the next layers. On the other hand, the positive gaps move to the conduction area of the positive strip, resulting in a potential difference between the surfaces of the two-link. The two surfaces can be connected by an electrical conductor to obtain an electric current in an electrical circuit, where electrons pass through the negative to the positive link, and thus light energy is converted into electrical energy. In this study, monocrystalline PV panels are used. Table II tabulates the characteristics of the used PV panels.

E. Power Conditioning Units
Generally, PV panels convert solar radiation energy to electrical energy and the electricity is produced in the form of direct current (DC). Therefore, the DC current must be converted to alternating current (AC). For this purpose, inverters are used. The specifications of the applied inverter used in this study are presented in Table III

F. Power Evacuation
For the proposed 10MW grid-connected solar plant, transformers with a rated power of 1.5MVA were utilized. The PV system is integrated into the grid by a DC/AC inverter, a step-up transformer, and an evacuating line of 33kV. The evacuation of power demands the reliability of the distribution system to be 99.5%. The efficiency of the transformer is almost 97%

G. Simulation Software Used
PVGIS (Photovoltaic Geographic Information System) is widely used for evaluating the performance of solar PV power plants. The European Commission has developed a web application with a geographical location interface for analyzing "Solar Resource Geographical Evaluation and Performance of Photovoltaic Technology". This tool contains a package, which includes solar radiation databases, performance evaluation methods, and estimates of economic parameters including electricity cost. PVGIS allows the user to choose the PV technology to be used in the system, enter system capacity requirement for installation and enter the permissible total system losses. It also allows the user to choose the slope or tilt angle and azimuth angle of the PV module. In order to assess the technical, economic, and environmental impact of renewable energy projects, RETScreen program was used. RETScreen is a clean energy management program to ensure energy efficiency, renewable energy, co-generation analysis, and continuous energy performance analysis. RETScreen is a useful tool for analyzing and assessing the viability of a gridconnected renewable energy system. In this study, important economic measures are the net present value (NPV), the internal rate of return (IRR), the flat energy cost (LCOE), the payback period (PB), the annual life cycle savings (ALCS), and the benefit-cost ratio (B-C) which are calculated using the RETScreen. Figure 2 presents the outline of the methodology used by the RETScreen Expert software.
• Equity payback (EP): • Annual life cycle savings (ALCS): • GHG emission reduction cost (GRC): • Capacity factor (CF)): where ܲ ௨௧ is the energy generated per year, ܲ is the installed capacity, N is the project life in years, ‫ܥ‬ is the after-tax cash flow in year n, r is the discount rate, C is the total initial cost of the project, ݂ ௗ is the debt ratio, B is the total benefit of the project, ‫ܩܫ‬ is the incentives and grants, ‫ܥ‬ is the annual energy savings or income, ‫ܥ‬ is the annual capacity savings or income, ‫ܥ‬ ோா is the annual Renewable Energy (RE) production credit income, ‫ܥ‬ ீுீ is the GHG reduction income, ‫ܥ‬ &ெ is the yearly operation and maintenance costs incurred by the clean energy project, ‫ܥ‬ ௨ is the annual cost of fuel, which is zero for renewable projects, and ∆ ீுீ is the annual GHG emission reduction.

A. Global Solar Resources
Two parameters, namely Global Horizontal Irradiation (GHI) and Direct Normal Irradiation (DNI) are used to analyze the solar resource in Libya. The annual averaged GHI, DNI, and TEMP values for all the locations are provided in Table IV. The values of GHI were found to vary from 2020.807kWh/m 2 to 2308.587kWh/m 2 . The maximum and minimum annual values of GHI are recorded in Al Kufrah and Tripoli, with a value of 2308.587kWh/m 2 and 2020.807kWh/m 2 respectively. Furthermore, it is found that the highest annual value of DNI of 2429.203kWh/m 2 occurs in Misratah and the lowest value (2267.607kWh/m 2 ) is recorded in Darnah. Additionally, it is noticed that the maximum and minimum value of air temperature is recorded in Ghat and Al Jabal al Akhdar with a value of 25.047 o C and 17.298 o C respectively.

B. SimulationRresults of Energy Generation and Capacity Factor
In this study, PVGIS software is used to find the optimum slope angle and azimuth angle for all selected locations in Libya. Table V lists the optimum angle for the future installation of a PV system for all chosen locations. RETScreen is utilized to investigate the feasibility of a grid-connected 10MW PV system in the selected locations. The mean monthly electricity generation from the proposed system is shown in Table VI. Figure 3 illustrates the annual electricity exported to the grid from the proposed PV system. It is observed that the highest annual electricity generation of 22067.128MWh is recorded at Al Kufrah and the lowest one of 17680.901MWh is obtained at Al Marqab. Moreover, based on the results of electricity generation for Al Kufrah and Al Marqab (see Table  VI), it is noticed that the maximum monthly electricity generation is achieved in July with a value of 1986.72MWh for Al Kufrah and 1847.528MWh for Al Marqab. The minimum monthly electricity generation is recorded in December for Al Marqab and Al Kufrah. The Capacity Factor (CF) for the proposed PV project for all chosen locations is presented in Figure 4.  acceptable values [10,26] and hence, it is technically sustainable to build and operate solar PV plants in the selected regions based on the technical viability of the solar system.

C. Simulation Results of Financial and Emission Reduction Analysis
Economic analysis is essential in order to know if the project is economically viable and sustainable. Studying the economic viability of PV power plant benefits and informs both investors and policymakers. The financial analysis worksheet of RETScreen software includes some financial parameters like inflation rate, discount rate, reinvestment rate, debt ratio, debt interest rate as input variables. Based on the input variables, Simple payback, Equity payback, Net Present Value (NPV), Annual Life Cycle Savings (ALCS), and Levelized Cost of Electricity were determined. Table VII shows the financial parameters including inflation rate, discount rate, debt ratio, debt interest rate, and project life which are used as input variables for assembly to be economically feasible. Based on the input variables the NPV, ALCS, and other financial parameters were calculated by the RETScreen software. According to [27], NPV and the payback period are the main economic viability factors in order to measure a PV project. According to our analysis, the NPV values for all regions are positive (see Figure 5), which indicates that the proposed project is estimated to be financially and economically feasible [10,27]. The simple payback period which is the length of time that will take to recoup the project's initial investment is shown in Figure 6. The proposed PV project in Al Marqab region has the longest payback period of    The emission analysis worksheet was used to calculate the GHG emission reduction resulting from carrying out the solar PV installation. The software calculates the gross annual GHG emission reduction for each of the 22 regions as shown in Figure 9. The project in Al Kufrah region has a maximum GHG emission reduction of 14025.28t CO 2 . It is followed by the project in Murzuq region whereas the least emission reduction is obtained from the project in Al Butnan region.  Renewable energy policies depend on a country's geography, population density, technical and financial capacity, and sovereignty obligations that govern deployment and development of its renewable energy sources [28]. In order to develop and promote renewable technologies and especially solar PV technology in a country, different policy suggestions and interventions are required. Generally, the successful renewable policy or market needs five steps that make up the policy design cycle, which are [28,29]: • Defining renewable energy sources targets • Identifying an appropriate strategy to reach the targets • Implementing the strategy • Enforcement and monitoring • Evaluation of compliance Additionally, a successful renewable policy or market depends on the technology-specific financial support [30]. However, there are some obstacles in using renewable energy in developing countries in general and Libya in particular, which are classified into financial, institutional, and technical constraints. Financial and economic constraints are considered the most important factors that affect utilizing renewable energy technologies as generation power in developing countries. These constraints are concentrated in the high capital cost of renewable energy projects with a lack (or absence) of financing mechanisms, in addition to the misconception that investing in such projects represents a financial risk. Also, some banks and financing sources may not encourage loans and investments in emerging fields compared to traditional energy projects, and this supports that investments in • Setting environmentally oriented policies such as exempting or reducing taxes on energy production from renewable and environmentally friendly sources, and setting taxes and fines on more polluting sources.
• Providing financial assistance and support and ensuring project loans that drive towards the use of renewable resources.
• Setting and developing standards and legislation related to new and renewable sources within the concept of all concerned partners.
• Reconsidering petroleum products pricing systems and linking them to fuel quality.
These must be held in addition to taking into account detailed project proposals that include a description of procedures, mechanisms and the proposed implementation schedule for the project, determining technical needs, techniques, equipment, and expertise needed for implementation, estimating the total value of investments and their terms, and assessing the direct and indirect financial benefits of the project.
Moreover, public awareness is categorized as one of the constraints of utilizing renewable energy technology. The lack of interest in using renewable sources for energy production and a misunderstanding of the nature of the work and applications of renewable energy technologies by the parties concerned and society at large is a major impediment to relying on clean sources for energy production. This obstacle strengthens the general feeling among institutions and individuals that there is little benefit in endeavors related to the environment and the feasibility of using systems that depend on varying natural phenomena (such as the sun and wind). Here, the role of information and awareness emerges to push towards the rehabilitation of individual and public opinion towards a correct concept of energy production from clean and environmentally friendly sources, bearing in mind that awareness is not limited to the media campaigns of the public and its encouragement to switch to new and renewable energy technology only. Rather, it should extend to repeated training and technical education through training programs, scientific seminars, workshops, and conferences for engineers and technicians, and decision-makers in the field of energy and transportation, which help clarifying economic, environmental, and technical facts in these areas.
V. CONCLUSIONS The problem of power outages continues to trouble the people of Libya since the civil war destroyed the substructure and transmission of the only source of electricity, while the quantities of fuel needed to operate the generation stations are reducing. This situation poses a challenge to the besieged Libyans and forced them to resort to many alternative options such as bringing small generators, storing electricity in car batteries, etc. However, the widening circle of generator users in Libya has left an atmosphere of noise and pollution not seen before, which prompted several researchers to investigate the potentiality of solar energy to generate electricity. Therefore, the investigation of the feasibility of a 10MW grid-connected PV system was made in this study. To achieve this, RETScreen software was utilized to determine the financial parameters and reduction of CO 2 emissions. The main findings of the current study are: • The annual average global horizontal irradiation of Libya is within the range of 1900-2700kWh/m 2 . The highest global horizontal irradiation is in the southern part of Libya, ranging from 2100 to 2500kWh/m 2 . These results indicate that Libya receives a huge amount of solar energy that can be used to generate electricity.
• The values of GHI varied from 2020.807kWh/m 2 to 2308.587kWh/m 2 . The maximum and minimum annual GHIs are recorded in Al Kufrah and Tripoli, with values of 2308.587kWh/m 2 and 2020.807kWh/m 2 , respectively.
• It was found that the highest annual value of DNI of 2429.203kWh/m 2 occurs in Misratah and the lowest value, 2267.607kWh/m 2 , in Darnah.
• Maximum and minimum value of air temperature is recorded in Ghat and Al Jabal al Akhdar.
• It is observed that the highest annual electricity generation of 22067.1284MWh is recorded at Al Kufrah and the lowest (17680.901MWh) is obtained at Al Marqab.
• The values of CF are within the range of 20.08%-25.07%. These values indicate that the selected regions are suitable for developing PV projects.
• Al Kufrah region has the lowest cost of electricity of 0.06564$/kWh and Al Marqab has the highest electricity cost of 0.0819$/kWh.
Based on the analysis, it can be concluded that Al Kufrah and Murzuq are the best locations for future installation of PV power plants from the annual energy and the economic parameters point of view.