Optimization of power supply for an isolated site from a hybrid renewable energy system,case study: Power supply of the island of El Aouana in Jijel,Algeria

Abstract

This article aims to design a hybrid renewable energy system for the autonomous power supply of a tourist complex planned on the island of El Aouana (Jijel, Algeria). This original application, based on real climate data from northern Algeria, aims to ensure permanent energy supply in this isolated site. An innovative connection scheme and rarely approached operational flexibility are introduced by combining a conventional connection to supply grid and different renewable hybrid system topologies. An economic multi-criteria comparison carried out with HOMER, between a PV/wind hybrid system, and a system combining photovoltaic sources, wind turbines, battery storage and back-up generator, shows that the PV/wind configuration responds effectively to seasonal variations in demand, sustainably reduces annual operating costs from $74.275 to $6.463, generates $17.704 in savings and avoids 289.283 g/year of CO₂, thus strengthening the energy and tourist sustainability of the site.

Keywords

diesel generator hybrid renewable energy systems isolated area optimization power grid solar panel storage battery wind turbine

Introduction

As eclectically isolated areas, electrical energy supply of islands is characterized by the absence of back-up systems, either by its non-existence, or by technical and financial constraints (Liu et al., 2018). Hence, any electrical power supply to these areas must be continuous and uninterrupted. This requirement is guaranteed by the integration of a reliable back-up system.

The wilaya of Jijel is a tourist region in the east of Algeria, with a coastline of around 120 km. As part of the drive to boost tourism in the city, it has been decided to create new tourist infrastructures. Tourist complexes are among the most important amenities in this area. One of these facilities will be located on an island in the El Aouana region, 20 km to the west of the capital of the wilaya of Jijel. The island of El Aouana, isolated in the Mediterranean Sea, covers an area of 37,600 m² and is located 865 m from the coastline and the electricity distribution network. This island is a key tourist destination within the region. The proposed project will be implemented in both electrically and geographically isolated conditions.

The island development strategy integrates advanced infrastructures and customized services, highlighting local natural and cultural resources, to provide authentic experiences. Sustainable energy and multisensorial approach are combined to support responsible tourism, long-term appeal, and regional competitiveness.

This paper aims to design the electrical power supply for this tourism project. There are two variants for electrical power supply of the project: The first variant is connection to the conventional grid, and the second is through a hybrid renewable energy system. The major drawback of conventional supply is its impracticality, particularly with regard to the maritime part. It causes heavy investment. This alternative has been studied and evaluated by the CARAT software (CARAT, 2011). Furthermore, as an electrical systems planning engineer with 18 years of experience at our country’s electricity and gas distribution company «SONELGAZ», I have observed that conventional power supplies are costly, disrupted and present implementation and maintenance problems, particularly where the subsea section is involved.

The El Aouana region presents a Mediterranean climate with predominantly sunny conditions, particularly in summer and spring. These climatic characteristics enable efficient exploitation of solar radiations for optimal photovoltaic energy production. The wind source is also sufficiently available, particularly during the winter and autumn seasons, allowing the operation of a well-determined number of wind turbines, to largely cover the requirements of our project. The wind and temperature profiles in the region have been validated using the HOMER software and the Algerian meteorology website. Many technologies have increasingly utilized free renewable energy resources, including the maritime sector, which is gradually adopting these resources in response to the recent expansion of renewable energy technologies (Bouhouta et al., 2022; Tanvir and Etminan, 2025).

Knowing the site’s geographical isolation, optimal power supply is targeted by exploiting the region’s favorable climatic conditions. The proposed system is based on a hybrid architecture integrating photovoltaic and wind sources, coupled with a battery storage system. Such a system contributes to preserve fossil fuels in the face of the growing global energy demand in recent years and rely on sustainable energy resources (SER) as a permanent alternative (Babatunde et al., 2025).

The reinforcement of the proposed system using diesel technology faces the problem of CO₂ emissions, which is in clear contradiction with the regulations outlined in the International Maritime Convention for the Prevention of Pollution, known as «MARPOL», stipulates the need to seek a new strategy for reducing emissions in shipyards (Babatunde et al., 2025; MARPOL, 2021).

These renewable marine systems based on offshore solar panels and wind turbines are produced by many companies, such as the Japanese company Eco Marine Power (Eco Marine, 2021), which markets and develops specific renewable energy systems for ships (Tanvir and Etminan, 2025). The detailed energy balance for the power to be installed is calculated based on similar projects, taking into consideration the daily and monthly peak operating hours, by introducing the various coefficients that are added to the calculation: simultaneity coefficient and utilization coefficient.

The main idea being studied and developed as part of this research is to prove the feasibility and economic and ecological efficiency of supplying the isolated tourist site, through a hybrid system with renewable energies, while ensuring the continuity of supply in complete safety to all the project’s equipment, whatever the climatic and meteorological conditions. Due to the site isolation, any power failure will result in general blackout and ensuing problems (Bouhouta et al., 2022). The study provides useful analysis in order to achieve two goals: The first goal is to eliminate the general blackout and guarantee better quality and continuity of service at the scale of isolated sites in general, and the second one is to promote the use of clean energy in the marine environment, in particular, and to preserve the environment and fossil fuels in general, in accordance with international agreements in this regard.

HOMER software is used to compare several configurations of hybrid photovoltaic/wind renewable energy system, where the results of the comparison yield the optimal configuration from a technical, economic, and environmental standpoint. This optimal configuration helps to mitigate the global impact of global warming by reducing greenhouse gas emissions.

This optimization of hybrid renewable energy system configuration is a complex process based on a number of essential stages that need to be taken into account:

Evaluation of available renewable energy resources

Analysis of energy demand

Optimal sizing of hybrid system components

Intelligent energy management

Integration of energy storage

Monitoring and maintenance

Technological evolution

HOMER software is dedicated to the design of micro-power networks, and the modeling and optimization of hybrid renewable energy systems (SHER) (Homer, 2024). HOMER’s optimization and sensitivity analysis algorithms make it easy to evaluate the many possible system configurations (National Renewable Energy Laboratory). The HOMER software package, developed by the National Renewable Energy Laboratory (NREL, 2024) in the United States (Razali and Hashim, 2010), includes several models of energy components such as wind turbines, photovoltaics (PV), hydroelectricity batteries, diesel generators and other fuels, electrolysis units and fuel cells. It evaluates the appropriate options, taking into account the cost and availability of energy resources (Bhutia et al., 2025). Based on the results obtained, and thanks to a comparative analysis, the PV/wind hybrid configuration achieves the desired objective by ensuring optimal power supply through a system with minimum cost and maximum reliability, while proving to be the most promising from a technical, economic, and ecological point of view (Al-Shamma’a and Addoweesh, 2014).

The case study of this paper concerns a continuous providing electricity supply for a planned resort project on a remote island, based on an optimal solution using various existing renewable energy sources. A stand-alone hybrid renewable energy system is designed to ensure the electrical energy supply of this complex, by combining several available renewable energy sources (photovoltaic, wind, etc.), reinforced by non-renewable elements; a storage facility consisting of a series of batteries, and a stand-by diesel generator comes into operation in the critical case, this system ensures the desired objective. Our project is part of the development of tourism in Jijel province, which boasts various territorial resources (cornice, coastline, islands, etc.).

The originality of this study, compared to previous work that generally focused only on the study of feasibility of renewable or hybrid systems, lies in the economic and technological comparison of the renewable energy solution with the conventional power supply via the distribution network, validated by the CARAT simulation tool. This comparative approach methodological contribution evaluates the performance of the system with and without conventional power supply, which makes it possible to quantify the real contribution of this variant to the energy mix (Ouderni et al., 2024). Although this option has certain drawbacks, it promotes resilience and continuity of supply, especially in isolated locations, by providing greater operational flexibility in the event of hybrid system failures or adverse weather conditions, a factor that is often overlooked in purely economic or environmental approaches.

The study also stands out for its original application to an island resort complex northern Algeria, characterized by highly fluctuating seasonal energy demand, whereas most existing research focuses on inhabited islands or isolated villages and low-density rural areas (Ashetehe et al., 2024; Azman and Sulistiawan, 2024). The use of the HOMER Pro optimization tool based on real climatic conditions rather than theoretical assumptions, enhanced by assumptions adapted to the island tourism context, reinforces the transferability of the proposed methodology to other similar sites (Ashetehe et al., 2024). Our approach is based on multi-criteria optimization that simultaneously integrates economic aspects (discounted energy cost, initial investment), environmental aspects (CO₂ emissions reduction) and technical aspects (service continuity, renewable energy penetration rate), while respecting the marine environment and reducing the use of fossil fuels. This approach enables realistic and operational compromises to be identified for the energy planning of island tourist facilities (Abirami et al., 2025; Babatunde et al., 2025).

The fundamental objectives of this research can be summarized as follows:

Optimize the energy balance in order to ensure a reliable and efficient dimensioning of the electrical installation.

Design, model, and optimize an autonomous hybrid system (PV–wind–storage) adapted to the maritime and touristic context, ensuring a reliable energy supply for an isolated insular tourist complex on El Aouana Island (Jijel, Algeria).

Reduce production, operation, and maintenance costs, while minimizing CO₂ emissions and dependence on fossil fuels.

Preserve the marine environment and contribute to sustainable tourism development.

Evaluate and compare the performance of different configurations, including back-up conventional supply, through a multi-criteria optimization integrating technical, economic, and environmental aspects.

Analyze the impact of local constraints (geographical and electrical isolation, solar irradiation, wind potential, and seasonal load profile) on system production and reliability.

Highlight the scientific originality of the approach, which combines energy resilience, operational flexibility, and the requirements of sustainable tourism in a rarely studied insular context.

Prevent blackout risks in this isolated site and ensure the continuity of the tourism investment under adverse climatic conditions, through a complementary study assessing the integration of conventional power as a reinforcement to the hybrid system.

This paper is organized as follows: Firstly, we began our study by analyzing energy requirements through a study of the load curve. It should be noted that the project’s peak consumption is recorded during the summer period, particularly in June, July, and August. Secondly, we then specified the Lambert coordinates to determine the geographical location where the project would be installed. This step is essential for obtaining the wind, temperature and sunlight profiles needed for the simulation carried out with the HOMER software. In third part of the work, once the sizing calculations have been carried out for the various elements making up the renewable energy production chain, two power supply options are proposed: the first one involves using the traditional grid, while the second one is based on hybrid sources combined with different topologies.

Finally, after modeling and analyzing the behavior of the two proposed configurations, the study concluded with an in-depth evaluation of the results obtained with a view to identifying the optimal solution from a technical, economic and environmental point of view. The chosen option avoids the need for substantial investment in a conventional connection, particularly given the geographical constraints and the maritime infrastructure required. Its main aim is to reduce dependence on fossil fuels and promote the use of renewable and sustainable resources.

Geographical location

The island of El Aouana is located in the Mediterranean, located opposite the seafront of the town of El Aouana. It is defined by Lambert coordinates: 36° 47′ 06″ North_ 05° 36′ 29″ East, and covers an area of 37 600 m². It is located at a distance of 865 m from the coastline and the electricity distribution network (Google Maps, 2025). Figure 1, taken from Google Maps, shows the location of the island and the geographical context of the project through an overview, specifying the distances to the coastline and the nearest distribution network, as well as a synoptic diagram of the proposed power supply configurations.

Specifications and design of the tourist complex

Project description

The project in question is part of the development of tourist activities in the region. It will involve the creation of an accommodation and leisure complex on the island of El Aouana.

Power balance and calculation note

The power balance study allows for sizing the electrical installation, including the transformer, cable cross-sections, protections, and control systems. It takes into account all the power ratings of the equipment installed and how it is used. To ensure that the installation operates correctly, several coefficients are added to the calculation (RSE, 2024):

P_{i n s t a l l e d} (k W) = \sum_{i = 1}^{n} P_{i} (k W)

(1)

with:

n

: the number of installed devices.

The installed power typically yields a value that is higher than the actual requirement, as not all receivers operate simultaneously or at full load. For this purpose, coefficients must be introduced to take account of their normal operating regime. The simultaneity coefficient $K_{s} (K_{s} < 1)$ characterizes the operating conditions of the installation, taking into account the fact that groups of receivers will not necessarily operate simultaneously, which will avoid oversizing the electrical installation. This coefficient depends on the number of circuits (IEC, 2020):

• $K_{s} = 0.9$ : if the number of circuits is 2 to 3

• $K_{s} = 0.8$ : if the number of circuits is 4 to 5

• $K_{s} = 0.7$ : if the number of circuits is 6 to 9

• $K_{s} = 0.6$ : if the number of circuits is 10 or more

The utilization coefficient $K_{u}$ ( $K_{u} < 1$ ) characterizes the load utilization rate as a function of the over time (NF C, 2020). This factor is introduced when the load is not operating at its rated capacity, in which:

• $K_{u} = 0.8$ : if a motor operates at 75% of its capacity

• $K_{u} = 1$ : If the load operates continuously for 24 hours

The formula for the total power used, based on the installed power values of various receivers, corrected by these coefficients, is as follows:

P_{u} (k W) = \sum_{i = 1}^{n} P_{i} (k W) * K_{u} * K_{s}

(2)

The impact of the two coefficients was considered in the optimization of the power. As shown in Table 1, the number of circuits was set to 7, within the range of 6 to 9, with a unit power weighted by a simultaneity coefficient

K_{s} = 0.7

. For motive power receivers such as the water pump and the mini-desalination unit, whose operation does not reach full load, the unit power was corrected by a utilization coefficient

K_{u} = 0.8

. The application of these coefficients optimized the installed power from 24.15 kW to a more realistic estimate of 15.90 kW (65.83%), thereby ensuring reliable system operation and directly influencing the sizing of the transformer and the upstream cable sections.

Table 1.

Load demand of the tourist complex.

Equipment details	Number of equipment	Unit power (W)	Simultaneity coefficient (Ks)	Utilization coefficient (Ku)	Rated current (A)	Rated voltage (V)	Total power (KW)
Lighting system (led lamps)	50	5	0.7	1.00	1	230	0.18
Fridge	2	300	0.7	1.00	2	230	0.42
Ovens (electric hob) (800 w + 2000 w)	2	2800	0.7	1.00	17	230	3.92
Water pump	1	2200	0.7	0.80	3	400	1.23
Washing machine	1	3000	0.7	1.00	9	230	2.10
Heating	5	1500	0.7	1.00	23	230	5.25
Mini-seawater desalination plant	1	5000	0.7	0.80	7	400	2.80
Total	62	14805	/	/	61	/	15.90

These adjustments reduce the retained power to ≈15.90 kW, corresponding to ≈17.7 kVA for cos φ = 0.9, thereby justifying, according to the available market ranges, the optimal choice of a 25 kVA three-phase transformer, supplied upstream by a 16 mm² copper section (25 mm² in Almelec), providing a safety margin. Conversely, directly considering the installed power of 24.15 kW would require the use of a 50 kVA transformer, supplied by a 35 mm² copper section (70 mm² in Almelec). This approach thus ensures a more realistic, reliable, and economically optimized sizing (NF C, 2020).

Table 1 describes the detailed energy balance for the power to be installed, based on similar projects. The complex is assumed to operate for half the year, during the period from April to September, depending on tourist activities and weather conditions (RSE, 2024; Touba clean energy, 2025).

Given that the energy demand is low and that there are no significant motor loads, except for the water pump and the mini-seawater desalination station, the transient regime has no influence on normal operation. Consequently, the start-up current can be neglected. Hence, the proposed renewable energy source does not require a large surface area to install the energy fields. Two scenarios are proposed in order to guarantee the supply of our project, either via the existing grid, or by using hybrid renewable energy sources reinforced by storage batteries. Our study aims to make the optimal choice between these two suggested variants.

Feeding variants for the project

Figure 1 summarizes the proposed solutions for powering the project. It shows two alternatives to be studied, specifying the type of energy and the physical consistencies to be implemented for the first solution.

Conventional power supply

The conventional power supply, derived from the medium-voltage distribution network, consists of conveying the energy via an aero-submarine medium-voltage line, over a distance of 02 km for the overhead section and 865 m for the submarine section. In order to prevent any possible disturbance caused by the underwater section, this line must be a dedicated feeder from the El Aouana 60/30 KV-2X40 MVA source substation, separate from the main distribution network. In a mixed feeder, the submarine section exerts a more significant impact than the overhead segments due to its high capacitance, which generates substantial homopolar capacitive currents. These currents increase fault levels, complicate protection selectivity and disturb the operation of adjacent feeders through capacitive overloads, overvoltage, and unintended tripping. This specificity requires treating the feeder as an underground link, disabling automatic reclosing, and implementing reactive compensation devices along with appropriately coordinated protection settings. Additional risks include transient over voltages caused by moisture and insulation defects, as well as environmental constraints such as corrosion, thermal variations, and mechanical stresses induced by marine currents. For this, the insulation of the submarine section through a dedicated incoming cell confines these risks, thereby enhancing selectivity, improving upstream equipment protection, and ensuring the continuity of service of the main network.

CARAT software stands for Automatic Calculation of a Tree Network. It simulates the behavior electric network both in medium and low voltage. It takes into account the essential parameters of the line, such as resistance, reactance, link lengths, and node-level loads. The calculation results present all the load-related constraints, such as line capacity overruns, power losses and unacceptable voltage drops at the various nodes, over a specific period, year by year (TDG SONALGAZ, 2018). In our case study, the power will be supplied from a 60/30 kV distribution substation with an installed capacity of 2 × 40 MVA. This power is distributed across eight 30 kV feeders, including a back-up power supply for each half-ram, as well as a power supply specifically dedicated to our load. The simulation concerns a structure to be built, comprising an overhead section of 2 km in Almelec with a cross-section of 34.4 mm², with a thermal limit of 140 A, and an underwater segment of 865 m in copper with a cross-section of 30 mm², with a thermal limit of 109 A. Because of the site’s isolation, a diesel generator will be installed to provide back-up in the event of incidents.

The supply study was carried out over a medium-term period of 5 years (2024-2028). Figure 2 shows the simulation results obtained using the CARAT software at the end of the study period. The maximum power demand in the system is 2.724 MW, while the total energy actually consumed over the studied period is 11,439.948 MWh. Total losses in the network, accumulated from the source and distributed over the various branches of the network, are 27 kW, representing 1.02% of the power consumed, which indicates that they are low and well controlled.

The overload rate, expressed as a percentage (%), corresponds to the proportion of capacity used on a branch, which is represented by a connection between two nodes (Node1 and Node2). According to the simulation results, no overload is detected. The voltage drop parameter (DV%) indicates the voltage difference between nodes. Values close to zero, with a maximum tolerated of around 0.88 %, reflect good voltage maintenance. This parameter depends mainly on the total length of the network, which amounts to 4860 km, including all the branches connected and the load to be supplied. The normal voltage drop is estimated at between ±10% of the voltage in use (TDG SONALGAZ, 2018).

The results indicate that the system is stable and operates under normal conditions, with no technical constraints linked to the transit capacities of the lines or the maximum voltage drop allowed at the nodes. Its design appears to be optimized to ensure sustainable operation. This optimization aims to efficiently meet current demand, with a low technical loss rate and a significant load margin, given the thermal limit of the cables. This indicates that the network is operating well below its maximum capacity, with a low transited load, providing sufficient reserve to accommodate potential future increases in demand.

The low load transmitted implies that the effective current remains below the thermal limit of the cables, guaranteeing a usable reserve capacity without risk of overheating, limiting thermal aging and preserving the integrity of the insulation. The low rate of technical losses confirms the low stress on the conductors, reflecting a minimum Joule effect dissipation ( $P_{j} = R_{i *} I^{2}$ ) and a more efficient energy transfer. These two parameters increase the difference between the operating current and the permissible thermal current of the cable, keeping the conductor at a moderate temperature. The correlation between low loading and low losses thus ensures stable nominal operation, a significant load margin linked to a reserve of residual thermal capacity and optimal use of the cables, able to sustainably absorb future increases in demand without exceeding thermal limits. The thermal limit of a cable defines the maximum allowable temperature of the conductor and its insulation, beyond which their electrical, mechanical and dielectric properties degrade. It determines the maximum current that can be supported in steady state without the risk of premature aging or cable failure, guaranteeing the safety and durability of the network. This thermal capacity depends on the properties of the materials, the type of installation (aerial, buried, underwater) and the ambient conditions influenced by various factors of derating, such as grouping, conductivity of the soil/marine environment, depth, and humidity. The major drawback of this conventional power supply is that there are no back-up systems available via the surrounding networks in the event of incidents, because of the site isolation.

The major drawbacks of this conventional power supply are summarized in the following points:

Due to the isolation of the site, there are no back-up systems available via the surrounding networks in the event of incidents

Costly solution, particularly regarding the subsea section expenses

The cost is disproportionate to the low load and the considerable investment

Disturbances to the overhead network result from the configuration of the air-submarine network, impacting protection settings, tripping and the overall stability of the network

Distorting the region’s landscape and tourism vision, particularly the seafront, due to the presence of the overhead network

The challenges of implementation and maintenance, particularly with regard to the underwater section

This alternative was rejected. However, despite its limitations, it remains a relevant back-up solution in the event of hybrid system failure due to weather conditions or other reasons. Furthermore, given the geographical configuration and the low impact of distances in relation to the strategic importance of the project and the expected benefits, this approach is justified in order to ensure continuity of supply in critical situations.

Power supply from renewable energy sources

Renewable energy has become a promising solution in terms of preserving the marine environment, unlike solutions based on fossil fuels. A total of 1.046 million tons of CO₂ is emitted by the entire navigation vessels, accounting for approximately 3.3% of global emissions (Yang et al., 2009). This reason encourages to power the project using hybrid renewable energy sources combined with storage batteries. The optimum choice of elements in the renewable energy production chain will be based on the availability of the various sources. The production system must be designed to be compatible with the marine environment, resisting corrosion, humidity and exposure to sea salt.

In order to meet needs continuously during night-time, or in the event of a lack of sunlight and/or wind, the system needs to be reinforced with batteries, or possibly a diesel generator. However, the final choice will be confirmed or rejected by an in-depth study. The use of a hybrid system with storage systems can guarantee reliable continuity of service in a site isolated from the electricity grid.

Figure 3 described the topology of the proposed hybrid energy system. The power supply is provided by photovoltaic source and win energy sources. If these sources encounter operational difficulties, the system will be reinforced by battery bank or diesel generator, both connected to the AC 230/400 V voltage bus.

The sizing methodology of the hybrid energy system can be summarized as follows (Upadhyay and Sharma, 2014):

Analysis of energy requirements and definition of expected energy consumption: by assessing the specific needs of the system or application concerned, this enables the optimum capacity and configuration of the hybrid system to be determined under different conditions of use.

Assessment of available energy sources: by identifying the sources available in the region or location where the system will be deployed. This may include renewable sources such as solar, wind and hydro, as well as conventional sources such as mains electricity.

Optimum sizing of system components: choosing the various elements that make up the system, such as solar panels, wind turbines, batteries, charge regulators and inverters, based on the characteristics of the energy sources identified and the system’s energy requirements.

Modeling and simulation: use modeling and simulation tools to assess the behavior of the system under different operating conditions. This approach makes it easier to adjust parameters and optimize component dimensions to maximize overall system efficiency.

Integration of storage systems: such as batteries, to ensure efficient energy management with a continuous supply in the event of fluctuations in energy sources.

Economic evaluation: is an economic analysis to assess the profitability of the system over its expected lifetime, considering initial and operational costs.

Continuous optimization (monitoring and maintenance): based on real-time monitoring data and effective system performance, making adjustments and improvements to continuously optimize energy and economic efficiency.

Modeling of the proposed hybrid energy system

Based on the calculated total power of 15.90 kW, the hybrid system meeting these requirements is distributed between the photovoltaic field, which represents 5.66 kW, made up of photovoltaic panels connected to a DC/DC step-up converter equipped with an MPPT function, and the wind farm, which covers the large part of the remaining 10 kW power by installing two wind turbines of 5 kW each. We did not resort to the option of a single 10 kW wind turbine due to ensuring back-up in the event of a wind turbine being withdrawn from operation.

In addition, a series of marine batteries, resistant to conditions at sea, will also be connected to a bi-directional DC/DC converter. All these elements will be brought together and connected to the DC bus.

The power generated by the photovoltaic system installed over a daily operating period of approximately 07 hours is expressed by:

P V K w h = 5900 X 7 = 41.30 [K w h]

(3)

Taking into account the average annual sunshine hours of 7.3 in the Jijel region, this means that the sun shines approximately 54% of the time (7.3 h/day). The power of the solar field is thus determined as follows (Jijel climate, 2024):

P V K w = \frac{41.30}{7.3} = 5, 66 [K w]

(4)

The formula for calculating the total number of panels to be installed is as follows:

N_{p v} = \frac{P_{c}}{P_{u}}

(05)

where:

P_{c}

: the peak power of the installation

P_{u}

: the unit power of the photovoltaic module

In our particular situation, the total number of panels to be installed is:

N u m b e r o f P V p a n e l s = \frac{566}{300} = 19 p a n e l s

(6)

Consequently, the current is determined from the following relationship:

I = \frac{P}{V} = \frac{300 X 19}{12} = 475 A m p s

(7)

with:

V

: the battery voltage

Opting for a battery with an individual capacity of 2000 Ah will optimize the number of batteries, while saving space and, of course, cost.

N u m b e r o f b a t t e r y = \frac{41300 X 4}{2000 X 0.8} \approx 103 b a t t e r i e s

(8)

Rate 0.8: presents the battery depth of discharge (PDB).

The power of the inverter compatible with our installation must be greater than 5 KW.

In summary, our system is made up of:

• Nineteen (19) photovoltaic panels, each with an output of 300 W, to cover part of the 5.66 kW output

• Two (02) wind turbines of 5 kW each

• Converters (DC/DC and AC/DC)

• One (01) 15 KW inverter

• 103 batteries of 2000 Ah each

• One (01) 50 KVA diesel generator

The aim of this provision is to guarantee a satisfactory and uninterrupted service, even in low sunlight and/or light wind conditions (Katiraei et al., 2007).

Description of the hybrid system components

The climatic conditions of the region in question are well adapted for installing a PV/wind hybrid system. Production elements, such as solar panels and wind turbines, must be designed to withstand marine conditions, including corrosion, humidity, high winds, and exposure to sea salt.

Photovoltaic modules

Offshore solar panels are among the types best suited to meeting the challenges posed by marine conditions. The mounting frame kits carrying the photovoltaic panels must be well fixed and correctly installed, respecting the optimum sun angle (51° for winter and 21° for summer), depending on the latitude at Jijel which is 36°, this is particularly true for installations on isolated sites, such as our case. These installations require optimum performance throughout the year (GPS of Jijel, 2024).

The optimum angle for tilting a solar panel is between 30° and 35°, ensuring that the collectors are perpendicular to the sun’s rays. This specific tilt angle varies according to latitude, with variations from one geographical area to another for photovoltaic panels (Mahfoud et al., 2022). The 300 W marine panel model to be employed, manufactured by MSI (Marine Solar Innovation Company), is characterized by (Marine Solar Innovation Company, 2021; Rehman et al., 2007):

• Panel size: 1640 × 992 × 35 mm.

• Maximum power: 300 W.

• Maximum current: 9.15 A.

• Maximum system voltage: 1000 V.

• Panel voltage: 32.8 V.

The monthly temperature and irradiance profiles are based on data from the official meteorological website and the HOMER software, as shown in Figures 4 and 5 (Windfinder, 2021). Based on the solar data previously collected by the HOMER software shown in Figure 5, in conjunction with those presented in Figure 4, it is possible to deduce an average annual temperature of 35.41°C at the site where the solar equipment is installed, with a peak recorded in July at 46°C. This temperature is accompanied by an average annual solar irradiation of 5.85 kWh/m², corresponding to a maximum recorded in October at 6.08 Wh/m² per day and a minimum in May at 5.680 kWh/m² per day. This temperature is accompanied by an average annual solar irradiation of 5.85 kWh/m², corresponding to a maximum recorded in October at 6.08 Wh/m² per day and a minimum in May at 5.680 kWh/m² per day. These data encourage us to use this type of energy.

The DC-AC converter

The Victron inverter to be used supports DC-AC conversion, while the MPPT function is provided via an MSI-MPPT battery charger, using an adaptive charging technique. To increase the output power on the AC side, it is necessary to install five sine wave inverters in parallel mode, thus allowing the power of 15 kW to be reached (Victron Energy, 2021).

The horizontal wind turbine system

The deployment of a wind system requires to determine the annual mean wind speed and its predominant direction. This involves data collection over an extended period of time. These data is then analyzed to identify optimal turbine location (Windfinder, 2021).

The insufficiency of a history of reliable meteorological data or the neglect of seasonal and topographic effects generate uncertainties likely to distort the estimation of the wind potential, to alter the accuracy of the production forecasts and to compromise the reliability of the simulations as well as the sizing of the system, reducing the robustness of the forecasts and the transferability of the results. These biases translate, from an economic point of view, into inappropriate investment costs, operational underperformance, and, consequently, a reduction in the financial viability and profitability of the project.

Figure 6 illustrates the average monthly wind speed in the El Aouana region, as measured by the HOMER software. The average annual speed is around 7.25 m/s. Such a high wind speed is very favorable for wind energy production, suggesting that the installation of wind turbines would be a viable option for exploiting this natural resource and producing electricity in a sustainable and environmentally friendly way. By comparing the data shown in Figure 7 with those presented in Figure 6, we deduce that the average annual wind speed in the region is around 7.25 m/s, with a maximum recorded during the first 3 months of the year at 8 m/s. The period from April to October records constant speeds of around 7 m/s. During the same period, conditions will be favorable for an increase in solar energy production. The prevailing wind direction is the west side, which allows the wind turbines to be perfectly oriented (Windfinder, 2021). These collected data guides our study towards the installation of two wind turbines of 5 kW each, operating at a speed of 40 m/s under a minimum wind speed of 2 m/s.

The ENAIR type 70 wind turbine, capable of producing 80 kWh/day at low wind speeds, is characterized by (Daud et al., 2011; Society; ENAIR, 2021):

• Wind speed: 60 m/s

• Maximum power: 5500 W

• Remote control system

• Only 1% above ambient noise

It’s an interesting feature to have a smart battery braking system built into the wind turbine. This not only protects the battery from overcharging, but also maximizes the use of available wind energy by resuming charging when levels fall below the battery voltage set point. This appears to be an effective design for optimizing the performance and durability of the wind turbine.

Wind turbine characteristics

Figure 8(a) shows the characteristics of the ENAIR 70 PRO/5.5 kW wind turbine, that is, power output as a function of wind speed. In our case, the wind system generates enough energy to meet the needs of our project. The range of wind speeds is from 0 to 30 m/s. During the start-up phase, at wind speeds of less than 3 m/s, the wind turbine does not generate any electricity. Energy production starts at 3 m/s. Between 3 m/s and 10 m/s, the power generated increases almost linearly, reaching a maximum of around 5 kW. At wind speeds of between 10 and 15 m/s, the turbine operates at optimum efficiency, reaching its maximum rated output of around 11 kW. At above 15 m/s, the turbine enters the power regulation phase, where output remains stable or decreases slightly to protect the system. This indicates the integration of a regulation mechanism, such as aerodynamic braking or blade orientation, designed to prevent overloads. A safety shutdown is recommended for very high wind speeds, in excess of 25 m/s. In this case, the turbine can be shut down completely to prevent any risk of structural damage. In the absence of significant fluctuations, or in the event of rapid variations in wind speed, the estimates provided by the anemometer can be used to assess the energy efficiency of the wind turbine. These data can also be used to draw a graph correlating these two parameters (Suchitra et al., 2019). In general, the curve shows that this wind turbine is well suited to the climatic conditions at our site, with an average wind speed of around 7 m/s, which is conducive to maximum energy production and guarantees the system’s profitability. A wind turbine with such a profile is an asset in a hybrid system, thanks to its ability to generate significant power in moderate to high wind conditions.

The left-hand side of Figure 8(b) shows the wind speed profile (in m/s) as a function of altitude (in m) in the El Aouana region. This led us to install the wind turbine at a minimum height of 15 m in order to obtain the desired power. Close to the ground, and for heights of 0 to 8 m, the wind speed is very low because of the roughness of the earth’s surface and the obstacles inducing a wind braking effect. However, above this altitude, there is a gradual and more marked increase in speed, reaching around 5 m/s at 15 m. This is due to the attenuation of the effects of friction with the ground, leading to a reduction in turbulence and a more stable flow.

The power of a wind turbine depends on the wind speed, so the longer the maximum wind speed is maintained, the more electricity is produced. The rotor blades are a key element in the efficiency of the wind energy production system. To optimize their design, it is essential to select at least one 2D aerodynamic profile segment, resulting in a smooth surface for the rotor blades (Suchitra et al., 2019). This type of profile is often observed in coastal or open areas such as El Aouana, where the influence of terrestrial friction diminishes rapidly with altitude. In wind engineering, this characteristic makes it possible to exploit stronger winds at higher altitudes to maximize energy production.

The energy storage system

Energy storage is done through a system of 103 batteries of 12 V 2000 Ah each. These batteries act as a secondary source, which come into service when the main sources are withdrawn, particularly during the night. It should be noted that energy consumption will decrease relatively during the night due to the withdrawal of certain loads; this is the case of a minimal service. With this configuration, our system largely meets our energy needs, while ensuring a continuous and uninterrupted power supply.

HOMER software simulation

The system simulated in the HOMER environment consists of the following elements:

• An alternative load (AC) estimated at 15.90 kW

• Nineteen (19) photovoltaic panels with a unit power of 300 W, forming a field of 5.90 kW

• Two (02) wind turbines of 5 kW each

• Converters (DC/DC and AC/DC)

• One (01) inverter of 15 kW

• A battery bank of 103X2000 Ah/12 V

• One (01) 50 KVA fixed-capacity diesel generator

The simulation considers various potential configurations, determining all the relevant information on the capacity of the energy source, the optimum size of the various components, as well as costs and emissions. The architecture of the HOMER software requires initial information, including energy resources, economic and technical constraints, energy storage requirements, and system control strategies (Rehman et al., 2007).

Results and discussion

The simulated wind-photovoltaic hybrid system is based primarily on the energy balance analysis detailed in Table 1. The favorable weather conditions and renewable energy sources available in the El Aouana region, whether from the data obtained from websites, as illustrated in Figures 4 and 6, or through HOMER, as presented in Figures 5 and 7, show a satisfactory convergence of results.

Figure 9 illustrates the daily consumption profile of our residential load, with the maximum load demand recorded during the time slots from 12:00 p.m. to 3:00 p.m. and from 8:00 p.m. to midnight, corresponding to the project’s peak hours. However, the monthly or seasonal peak shown in Figure 12 mainly manifests itself during the summer period, that is to say June, July, and August, depending of course on the nature of our project in terms of electricity consumption.

Figure 10 presents an analysis of the data in the form of hourly graphs, illustrating the projected energy consumption profiles for each month of the year, which show a strong similarity with the profiles observed on a daily basis. The Daily energy consumption is minimal between 00:00 and 06:00, reflecting a drop in activity, before gradually increasing after 06:00, corresponding to the start of morning activities such as heating, lighting and the use of electrical appliances.

The main peak in consumption is generally observed in the late afternoon or early evening, due to the intensive use of electrical appliances and lighting. However, the amplitude of these variations varies from month to month, influenced by factors such as the outside temperature (heating or air conditioning), the length of daylight (lighting) and the level of human activity.

Seasonal variations show higher consumption during the winter months, particularly in the evenings, mainly due to colder climatic conditions induced by wind and marine humidity, the short duration of sunshine reducing natural brightness and the concentration of activities in indoor spaces during long nights, the needs for heating and lighting increase, resulting in a significant increase in energy consumption. On the other hand, during the summer months of June, July, and August, consumption is relatively more stable and slightly reduced, and this period is characterized by a preponderance of outdoor activities and a decrease in energy consumption, reflecting the non-use of heating, while air conditioning only partially contributes to the increase in demand. The cooling sea currents moderate the ambient climate and reduce, or even eliminate, the need for air conditioning. Moreover, the duration of sunshine, which is longer than in winter, limits the use of lighting, as demand then focuses mainly on basic services.

The months of May, September, and October show moderate variations, reflecting relatively balanced energy needs. The analysis of these profiles in HOMER makes it possible to determine the specific energy requirements for each month and to optimize the energy production and storage systems, taking into account seasonal and hourly variations.

These seasonal fluctuations generate several challenges and compromises that force the designer of the energy system to find a balance between installed capacity, operational flexibility and overall cost. The main issues relate to the risk of oversizing or underutilization of equipment, optimal storage management and the integration of renewable sources with variable production. The objective is to reconcile continuity of service and economic optimization, despite the variability of renewable resources and the constraints inherent in the island context. This compromise requires the implementation of a hybrid architecture combining renewable production, storage devices, and emergency means, driven by an intelligent management system, ensuring the reliability, profitability, and resilience of the system against seasonal and hourly fluctuations.

The upper part of Figure 11 shows the monthly variations in wind speed in the El Aouana region, simulated using the HOMER software. The recorded speeds vary between 0 and 20 m/s throughout the year, with a daily level of detail allowing significant fluctuations to be observed. These alternate between periods of low intensity and peaks exceeding 15 m/s, reflecting a highly variable and energetically exploitable wind regime. This dynamic highlights the temporal variability of the wind potential, a determining factor for the sizing and optimization of the hybrid system, and underlines the need for complementary integration with the solar resource in order to ensure stable energy production throughout the year. The periods from January to March and from November to December are distinguished by high wind speeds and frequent peaks, reflecting a season dominated by anemometric conditions favorable to wind production. Conversely, during the summer period (June to August), the wind speed remains lower and stable, marking a less windy phase. This seasonal variability highlights the complementarity between wind and solar resources, the decrease in wind production can be effectively compensated by increased photovoltaic production, thus ensuring the continuity and stability of energy supply.

Isolated extreme peaks in excess of 15 m/s are observed throughout the year, reflecting specific episodes of strong winds, such as gusts or storms. These observations confirm the relevance of the choice of location, suggesting that the El Aouana region has promising wind energy potential, particularly during winter and early spring, offering optimal opportunities for maximizing wind energy production. The daily and seasonal variability of the wind regime must be taken into account in the analyses in order to ensure optimum sizing of wind energy systems. In contrast the lower part of Figure 11 shows the monthly variations in the ambient temperature in the El Aouana region, modeled using the HOMER tool. The curve highlights a seasonal thermal profile characteristic of the Mediterranean climate, with an annual amplitude of about 20° C. Temperatures gradually increase from January to August, reaching a marked summer peak, before decreasing regularly towards the end of the year. This evolution reflects the overall thermal stability of the region and highlights a predictable seasonal cycle, favorable to the planning and optimization of energy, agricultural and tourist activities. Such regularity is also an asset for the sizing of hybrid systems, making it possible to efficiently adapt energy production to local climatic conditions.

In winter, temperatures of between 5 and 10°C indicate a cold period. They rise gradually in spring to reach around 15 to 25°C, marking a transition to warmer conditions. In summer, they exceed 25°C, with a maximum observed in late July or early August, reflecting hot summer conditions. The favorable summer temperatures encourage the development and exploitation of renewable energies in this region, while they gradually decrease in autumn, returning to around 15°C in November. This variation is consistent with a coastal region where maritime influences moderate extreme temperatures.

The left-hand side of Figure 12 shows the seasonal profile of power demand for the new system proposed and simulated under HOMER. The monthly load variations are represented by the central line of each box, indicating the average values, and by the limits illustrating the extreme variations. This system is designed to supply alternating current (AC) loads, typical of domestic equipment and residential applications. The energy demand presents a homogeneous and well-balanced distribution throughout the year, characterized by optimized consumption and well-controlled power peaks, accompanied by slight seasonal variations. This regularity reflects a stable load that is slightly dependent on weather conditions, confirming the relevance of the sizing of the hybrid system for constant and moderate load applications. Such operational stability strengthens the reliability and durability of the system, while promoting better long-term energy management.

The scaled values enable the performance and viability of the system to be analyzed for reduced configurations or for configurations adapted to specific needs. The right-hand side of Figure 12 shows the metrics table and load analysis. The proposed system provides an average daily production of 15.9 kWh, with a peak power of 23.34 kW. It takes into account a partial night-time period of 8 hours, from 01:00 to 09:00, during which the minimum average load is 2.38 kW, reflecting optimization of the system to avoid consumption peaks. In this context, the HOMER software seeks to identify the optimal scenario that minimizes costs, giving priority to maximum use of renewable energies and avoiding as far as possible the use of a diesel generator, in order to limit polluting emissions. The constant load factor of 0.28 reflects moderate use of the system, providing scope for optimizing capacity or integrating additional renewable energy sources. Its stability during the night-time period shows that the reduction in demand does not alter the overall characteristics of the system, with consumption proportionally well distributed in relation to maximum capacity.

The calculation report generated from simulations performed in HOMER, highlighting 240 potential configurations of hybrid energy systems. Of these, 216 solutions have proven to be technically feasible, satisfying the defined feasibility criteria, in particular in terms of energy production and demand coverage. On the other hand, 24 configurations were discarded due to capacity limitations, not allowing to ensure stable operation of the system. In addition, 240 other combinations were automatically excluded due to the configuration of the components: 232 due to the absence of a converter, an essential element for energy conversion, and 8 due to the presence of a converter not required, making these options redundant or suboptimal. The analysis thus highlights the rigor of the selection process and highlights the need for a storage device to compensate for the intermittency and variability of renewable sources. The integration of such a system constitutes an essential condition for the operational stability and the continuity of the energy supply, reinforcing the robustness and the reliability of the proposed hybrid system.

Figure 13 shows the results of the simulation carried out using HOMER software for the optimal system configurations. It details the configuration of the system for each scenario, analyzing costs and performance, where we can know both the operating and maintenance costs, the cost of fuel, the cost of capital and the nominal capacity of the system. This has enabled us to carry out comparative analyses and explore the different variants and alternatives considered in order to arrive at the optimum solution.

This simulation demonstrates that it is possible to design a sustainable energy system without using a diesel generator, while remaining economically competitive. The optimized system, shown in line 02 of Figure 13, consists of:

• CS6U-330P (kW): Total capacity of 5.90 kW produced by the solar panels.

• Generic 10 kW: Wind farm consisting of two wind turbines of 5 kW each.

• Power Safe SBS 1500: Series of 50 1500 Ah battery units for storing surplus energy.

• Converter 15 kW: Inverter for conversion between DC energy sources and AC loads.

The system uses the “Cycle Charge” (CC) management mode, which involves recharging the batteries as soon as conditions allow. From a technical point of view, the optimum solution will ensure that the desired load demand is produced, while guaranteeing optimal operation in the best possible conditions. The absence of a diesel generator offers an ecological advantage by limiting the impact on the ecosystem and reducing CO₂ emissions. From an economic point of view, the NPC (Net Present Cost) corresponds to the total discounted cost of the system over its lifetime, including initial, operating and future replacement costs. In our case, an NPC of $131.949 is optimal compared with other configurations, which can cost up to $646.036. The COE (Cost of Energy), expressed in $/kWh, representing the cost of the energy produced in $/kWh, is an essential indicator for assessing the profitability of the system. The COE in our case, evaluated at 1.76 $/kWh, is economically viable and competitive for a hybrid installation. Compared with the parameters of the last configuration, the cost is multiplied by 5, reaching 8.61 $/kWh, which reduces their profitability. The Operating Cost, expressed in $/year, is the annual cost of operating and maintaining the system, estimated at $1.570. It includes maintenance, replacement and other recurring costs. This cost is lower by a factor of 25 if a wind system coupled to a diesel generator, estimated at $40.304, is adopted. On the other hand, the initial capital cost of the optimal configuration is estimated at $111.655. This amount corresponds to the initial net investment cost required to set up the configuration, excluding any other variable or external factor having an influence. Some configurations require a higher initial investment of up to $136.655.

In summary, the optimized system, based on renewable energy sources, presents a coherent balance between the initial investment cost, operating expenses and energy performance, in particular in terms of net discounted cost (CNP) and energy cost (COE). The results obtained underline the relevance of the chosen dimensioning, which makes it possible to achieve an optimal compromise between economic profitability and energy efficiency. In the long term, this configuration proves to be economically advantageous and sustainable, confirming its ability to ensure a reliable supply of energy while reducing costs and environmental impact.

Figure 14 illustrates the proportions of energy supplied in the new configuration. It shows the maximum power output from renewable energies during the months of November, December, January, February, and March. This is due to the pleasant temperatures in the El Aouana region and the favorable wind speeds during this period of the year. A significant energy surplus is produced during the period from November to April, due to favorable wind speeds and thermal conditions. The surplus energy produced by the photovoltaic section is used to recharge the batteries, which store this energy so that it can be used to cover low night-time consumption, when solar sources are not available, or in the event of other constraints. The figure in question illustrates also the contribution of each component of the renewable chain to electricity production. The optimized system generates an annual energy of 9457 kWh from the photovoltaic field, a contribution of 42.10%, and 13,006 kWh/year from wind power, representing 57.9% of the total production. These results confirm that the system effectively achieves its energy supply objective under optimal operating conditions. It is also observed that the contribution of wind turbines remains limited between the months of May and September, unlike the rest of the year. This seasonal variation is explained by a relative decrease in wind speed and more moderate climatic conditions characteristic of the El Aouana region. This trend underlines the importance of complementarity between photovoltaic and wind sources, guaranteeing stable electricity production adapted to local climatic fluctuations.

Figure 15 shows the seasonal variation in energy production from the renewable system. Maximum power is mainly observed at the beginning of the year, characterized by significant fluctuations due to favorable weather conditions and the efficiency of the renewable energy sources on site. This performance can be explained in particular by stronger winds in winter or adequate solar exposure. For the summer period, from June to August, energy production is relatively stable, although the peaks appear to be slightly lower than in winter. This trend could be explained by a reduction in the contribution from wind power, partially offset by increased performance from solar panels, favored by the intensity of sunshine during the summer.

Energy production during the autumn season remains relatively stable, although significant variations are still observed, indicating greater sensitivity to fluctuations in local weather conditions. Production peaks reach around 16 kW, indicating that the system has been properly sized to make the most of favorable conditions, such as strong winds or intense sunshine. Conversely, production sometimes falls to minimum values close to zero, probably due to periods with no wind or heavy cloud cover. This highlights the system’s dependence on climatic conditions and renewable resources, which are not always available at full capacity.

Throughout the year, renewable energy production varies significantly, with peaks and troughs reflecting fluctuations in the renewable resources exploited by the hybrid system, such as gusts of wind or intermittent sunshine. Although the hybrid system is capable of producing energy all year round thanks to the combination of the two sources of energy, allowing shortfalls in one to be compensated by the other, fluctuations due to climatic conditions and seasonal variations highlight the need to integrate storage solutions. Devices such as batteries can be used to store excess energy produced during periods of high production and release it during off-peak periods, thereby increasing the efficiency of the system. In addition, an alternative back-up source, such as a diesel generator, could be essential to make up for shortfalls in renewable production. The relationship between the output power of the diesel generator (kW) and its fuel consumption (L/h) shows a linear trend, indicating that an increase in energy production is accompanied by a proportional increase in fuel consumption, reflecting the typical efficiency of diesel engines.

The results indicate that the power range of the diesel generator extends from 0 to 50 kW, with a proportional fuel consumption, varying from 0 to 15 L/h. This quasi-linear evolution reflects a stable energy efficiency, without significant fluctuations in performance, which confirms the correct dimensioning of the generator set in the hybrid system. The optimal operating range of the generator, corresponding to use under normal load conditions, although this interpretation may depend on the specific parameters of the model studied. On average, the generator consumes 1.65 L of fuel per hour for a daily autonomy of about 7 hours, that is, a total annual consumption of 17,704 L, corresponding to an estimated annual cost of $17,704.00. In addition, it emits 16.34 g of CO₂ per liter of fuel, that is, annual emissions estimated at approximately 289,283.36 g, highlighting the significant environmental impact of this component. These results underline the need to optimize the use of the diesel generator within the hybrid system, in particular by increasing the share of renewable energies and storage, in order to reduce both fuel consumption and greenhouse gas emissions, while maintaining the reliability of the power supply.

Summary of costs

Table 2 provides a detailed cost analysis of the validated optimal solution. The system is optimally designed to reduce operating and maintenance costs, while ensuring reliable energy production. The system requires a total initial investment of $8637.00. This includes the costs of the solar panels, batteries, generator and inverter. However, the total net present cost (NPCC) of the system over a 20-year period is $10,206.80.

Table 2.

Summary of optimal system costs.

Component	Capital ($)	Replacement ($)	O&M ($)	Salvage ($)	Total ($)
Canadian Solar MaxPower CS6U-330P	205.38	0.00	0.00	0.00	205.38
EnerSys PowerSafe SBS 1500	3867.72	0.00	0.00	0.00	3867.72
Generic 10 kW	3867.72	1233.06	500.00	694.91	4905.87
Leonics STP-219Cp 15 kW	696.19	615.04	0.00	83.39	1227.84
System	8637.00	1848.10	500.00	778.30	10,206.80

The cost of the system elements is distributed as follows:

The solar panels (Canadian Solar MaxPower CS6U-330P) have an initial cost of $205.38, with no replacement or operating costs. This shows that they have a long service life and require little maintenance.

The batteries represent a significant cost, with an initial investment of $3867.72. No replacement costs are anticipated, which suggests a service life equivalent to that of the PV system.

The wind generator costs $3867.72 to install, but also includes $1233.06 for replacement over its lifetime. Operating and maintenance costs are $500, reflecting the expenses associated with running it.

The inverter (Leonics STP-219Cp 15 kW) has an initial cost of 669.19, with a planned replacement at 615.04. This implies that it will need to be replaced at least once during the lifetime of the system.

Lifetime replacement costs for the system amount to $1848.10, mainly related to the generator and inverter. On the other hand, operation and maintenance (O&M) costs are relatively low at $500, reflecting the low maintenance requirement for the system as a whole. The amount of $778.30 represents the total residual value (salvage) of the remaining components at the end of the system’s lifetime, in particular the generator and inverter. It should be noted that the batteries and the generator represent the main items of expenditure, because of their essential role in energy storage and the production of back-up power.

Emissions into the environment

The replacement of conventional energy systems by renewable sources would reduce annual CO₂ emissions by approximately 289,283.36 g/L, thus contributing to the limitation of atmospheric pollution and the preservation of the local environment. This reduction is part of the Algerian national plan for energy transition and the fight against climate change, in accordance with the country’s international commitments. In addition, taking into account the estimated cost of one ton of carbon dioxide, estimated in 2018 at between $60 and $80 (Maalawi, 2020), to which the operating and maintenance costs are added, the adoption of a low-carbon hybrid system presents a major economic and environmental advantage, confirming the relevance of integrating renewable energies into the national energy strategy.

Results of the comparison of costs and emissions

The following is a comparison of the costs of fuel consumption, operating and maintenance costs and CO₂ emissions between the conventional system and the renewable energy system, whether used with or without a diesel generator.

Table 3 compares the three energy supply alternatives, in terms of costs and emissions; the first scenario corresponds to supply from the distribution grid, the second to a system combining two sources of renewable energy and a diesel generator, and the final configuration to a hybrid system based exclusively on renewable energy. Analysis of this table has enabled us to confirm that the adoption of clean energy offers significant economic advantages, both in terms of the cost of producing energy and the cost of operation and maintenance. An annual saving of $17,704.00 on fuel consumption will be achieved. As a result, the diesel generator-enhanced solution is the most expensive option due to its extended lifespan (Berry and Ibrahim, 2023). This solution will prevent the emission of 289,283.36 g of CO₂/year, helping to protect environment. On the other hand, the diesel-powered system remains the most polluting of the three solutions. The annual operating and maintenance cost of the photovoltaic-wind system alone, at $6463.76, is significantly lower than that of the system integrating the diesel generator or using the distribution grid. This reflects the simplicity and durability of renewable equipment, which requires little maintenance.

Table 3.

Results of the cost comparison.

Supply mode	Duration (hours/year)	Fuel consumption (L/year)	Fuel cost ($/year)	O&M cost ($/year)	CO₂ emissions (g/L/year)
Distribution network	7 × 365	0	0	7504.13	0
Wind-PV Renewable System with Diesel Generator	7 × 365	17,704.00	17,704.00	74,275.05	289,283.36
Renewable system Wind-PV	7 × 365	0	0	6463.76	0

Annual fuel consumption, at 17,704 L, reflects the use of the diesel generator as a back-up source of renewable energy, while the annual O&M cost of the system including the diesel generator was $74,275.05, taking into account oil consumption and the cost of spare parts. This is the highest of the three evaluated systems. This solution can be considered as a back-up in the event of insufficient renewable sources, but it is not ideal in the long term. The grid-based solution is a simple option, with no fuel consumption and no direct CO₂ emissions. However, it does have an indirect environmental impact linked to the production of electricity for the grid, which may include fossil fuel sources. However, the cost associated with this solution is particularly high, due in particular to the expenditure associated with the subsea section, including installation, maintenance and production costs. Its access costs, at 7504.13 $/year, are fixed and offer limited competitiveness compared with a system based entirely on renewable energy sources.

Benefits

The photovoltaic-wind turbine solution alone is less expensive than a hybrid system incorporating a diesel generator or conventional power supply

A clean and totally autonomous solution

Helps to preserve the marine ecosystem

Avoids the need for a diesel generator, reducing CO2 emissions and preserving fossil fuel resources

Aesthetically pleasing installations that blend harmoniously into the island’s landscape

Drawbacks

The lifespan of production line equipment is limited compared to that of conventional systems.

Specific maintenance of the various pieces of equipment is required to cope with the difficult marine conditions.

To carry out maintenance and surveillance tasks, we constantly have to cross a maritime zone, with all the challenges involved in carrying out these tasks.

Conclusion

The comparative study between several power supply scenarios for an isolated tourist site, allows us to draw the following conclusions:

Powering the site through a hybrid renewable energy system is much better, economically and ecologically, compared to powering it through the conventional grid based on fossil resources.

Conventional grid connection of the isolated island is, in principle, ruled out. However, given the geographical configuration and the low impact of the island distance from the coast in relation to the strategic importance of the project and the expected benefits, this conventional connection represents a relevant back-up solution, as an energy mix for enhance the stability of power supply and eliminate the general blackout.

The combination of both photovoltaic and wind resources in the same hybrid system makes it possible to cover the seasonal and daily variability and intermittency of these renewable resources, through optimal management.

The inclusion of a diesel generator in the photovoltaic-wind hybrid system increases the annual operating and maintenance costs from $6463.76 to $74,275.05, and requires an amount of $17,704.00 as fuel consumption-related production coast. In addition, it causes CO₂ emission of 289,283.36 g/year.

In return, the inclusion of diesel generator and battery storage ensures the continued supply of the isolated site in the event of a failure of renewable resources.

The use of real meteorological data instead of theoretical assumptions ensures better convergence and enhances the reliability of the results.

The optimization of the power balance allowed a reliable and efficient dimensioning of the system equipment.

The results show that the optimal configuration of the power supply is based on 42.10% photovoltaic power and 57.9% wind power, confirming the effectiveness of the proposed model in achieving an optimal and sustainable energy supply.

The results obtained validate the effectiveness of the proposed power supply model and demonstrate that the integration of green energy, particularly in the maritime sector, is a sustainable and promising alternative. Furthermore, the favorable climatic conditions and high renewable energy potential of the El Aouana region make it and ideal location for the installation of sustainable energy infrastructure, highlighting the need for in-depth study with a view to large scale implementation.

Footnotes

ORCID iD

Kamel Bedrine

Author contributions

Pr. LALILI has revised and supervised the redaction of the paper.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Furthermore, the authors confirm that all figures and documents included in this manuscript are used in full compliance with legal and ethical standards.

Data Availability Statement

The authors declare that all underlying data for the results presented in this study will be made available upon reasonable request.*

Author identification

Electrical and gas systems planning engineer for 18 years within the electricity and gas distribution company «SONALGAZ» in Algeria.

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