Role of hybrid (wind+diesel) power systems in meeting commercial loads

The utilization of energy from renewable sources, such as wind, is becoming increasingly attractive and is being widely used for the substitution of oil-produced energy, and eventually to minimize atmospheric degradation. Literature shows that commercial/residential buildings in Saudi Arabia consume an estimated 10–40% of the total electric energy generated. In the present study, hourly mean wind-speed data for the period 1986–1997 recorded at the solar radiation and meteorological monitoring station, Dhahran (26° 32′ N, 50° 13′ E), Saudi Arabia, have been analyzed to investigate/examine the role of hybrid (wind+diesel) energy conversion systems in meeting the load requirements of a typical commercial building (with annual electrical energy demand of 620,000 kWh). The monthly average wind speeds for Dhahran range from 4.1 to 6.4 m/s. The hybrid systems considered in the present analysis consist of different combinations of the commercial 10 kW wind energy conversion systems (WECS), supplemented with battery storage unit and diesel back-up. The study shows that with thirty 10 kW WECS and 3 days of battery storage, the diesel back-up system has to provide 19% of the load demand. However, in the absence of battery storage, about 40% of the load needs to be provided by the diesel system.     

Parametric study of hybrid (wind + solar + diesel) power generating systems

The combined utilization of renewables such as solar and wind energy is becoming increasingly attractive and is being widely used for substitution of oil-produced energy, and eventually to reduce air pollution. In the present investigation, hourly wind-speed and solar radiation measurements made at the solar radiation and meteorological monitoring station, Dhahran (26°32′N, 50°13′E), Saudi Arabia, have been analyzed to study the impact of key parameters such as photovoltaic (PV) array area, number of wind machines, and battery storage capacity on the operation of hybrid (wind + solar + diesel) energy conversion systems, while satisfying a specific annual load of 41,500 kWh. The monthly average wind speeds for Dhahran range from 4.1 to 6.4 m/s. The monthly average daily values of solar radiation for Dhahran range from 3.6 to 7.96 kWh/m². Parametric analysis indicates that with two 10 kW wind machines together with three days of battery storage and photovoltaic deployment of 30 m², the diesel back-up system has to provide about 23% of the load demand. However, with elimination of battery storage, about 48% of the load needs to be provided by diesel system.     

Prospects of autonomous/stand-alone hybrid (photo-voltaic + diesel + battery) power systems in commercial applications in hot regions

Most of the world’s energy consumption is greatly dependent on fossil fuel, which is exhaustible and is being used extensively due to continuous escalation in the world’s population and development. This valuable resource needs to be conserved and its alternatives need to be explored. In this perspective, dissemination and utilisation of renewables such as solar energy has gained worldwide momentum since the onset of oil crises of 1970s. Moreover, burning of fuels is the principal cause of air pollution, and possibly environmental warming. Saudi Arabia, being blessed with a fairly high level of solar radiation, is a suitable candidate for deployment of solar photo-voltaic (PV) panels for power generation during crisis. Literature indicates that commercial/residential buildings in Saudi Arabia consume an estimated 10–45% of the total electrical energy generated/consumed. In the present study, hourly mean solar radiation data for the period 1986–1993 recorded at the solar radiation and meteorological monitoring station, Dhahran (26° 32′ N, 50° 13′ E), Saudi Arabia, have been analyzed to investigate the potential of utilizing hybrid (PV+diesel) power systems to meet the load requirements of a typical commercial building (with an annual electrical energy demand of 620,000 kWh). The monthly average daily solar global irradiation for Dhahran ranges from 3.61 to 7.96 kWh/m². The hybrid systems considered in the present analysis consist of different combinations of PV panels/modules (different array sizes) supplemented with a battery storage unit and diesel back-up. The study shows that with a combination of 3700 m² PV together with 12 h of battery storage, the diesel back-up system has to provide 6% of the load demand. However, in the absence of a battery bank, about 56% of the load needs to be provided by the diesel system.     

Performance evaluation of hybrid (wind/solar/diesel) power systems

Depleting oil and gas reserves, combined with the growing concerns of global warming, have made it inevitable to seek alternative/renewable energy sources. The integration of renewables such as solar and wind energy is becoming increasingly attractive and is being used widely, for substitution of oil-produced energy, and eventually to minimize atmospheric degradation. The literature shows that commercial/residential buildings in Saudi Arabia consume an estimated 10–40% of the total electric energy generated. In the present investigation, hourly wind-speed and solar radiation measurements made at the solar radiation and meteorological monitoring station, Dhahran (26°32′ N, 50°13′ E), Saudi Arabia, have been analyzed to investigate the feasibility of using hybrid (wind+solar+diesel) energy conversion systems at Dhahran to meet the energy needs of twenty 2-bedroom houses. The monthly average wind speeds for Dhahran range from 4.1 to 6.4 m/s. The monthly average daily values of solar radiation for Dhahran range from 3.6 kWh/m² to 7.96 kWh/m². The performance of hybrid systems consisting of different rated power wind farms, photovoltaic (PV) areas, and storage capacities together with a diesel back-up are presented. The monthly average daily energy generated from the above hybrid system configuration has been presented. The deficit energy generated from the back-up diesel generator and the number of operational hours of the diesel system to meet a specific annual electrical energy demand of 702,358 kWh have also been presented.     

Opportunities for utilization of stand-alone hybrid (photovoltaic + diesel + battery) power systems in hot climates

There is a growing awareness that combustion fuels are a limited resource and burning of these fuels is the principal cause of air pollution, and possibly environmental warming. This recognition is elevating interest and activity toward the development and application of alternative/renewable sources of energy, such as solar energy to displace some of the use of fossil fuels. In this context, Saudi Arabia being enriched with fairly high degree of solar radiation, is a suitable candidate for deployment of solar photo-voltaic (PV) panels for power generation in crisis. Literature shows that residential buildings in Saudi Arabia consume about 47% of the total electric energy generated/consumed. In the present study, hourly mean solar radiation data for the period 1986–1993 recorded at the solar radiation and meteorological monitoring station, Dhahran (26° 32’ N, 50°13’ E), Saudi Arabia, have been analyzed to examine/investigate the potential of utilizing hybrid (PV + diesel) power systems to meet the load requirements of a typical residential building (with annual electrical energy demand of 35 200 kWh). The monthly average daily values of solar global irradiation for Dhahran range from 3.61 kwh/m² to 7.96 kwh/m². The hybrid systems considered in the present analysis consist of different combinations of PV panels/modules (different array sizes) supplemented with battery storage unit and diesel back-up. The study shows that with 225 m² PV together with 12 h of battery storage, the diesel back-up system has to provide 9% of the load demand. However, in absence of battery bank, about 58% of the load needs to be provided by the diesel system.     

Optimal sizing of battery storage for hybrid (wind+diesel) power systems

Hourly mean wind-speed data for the period 1986–1997 [except the years 1989 (some data is missing) and 1991 (Gulf War)] recorded at the solar radiation and meteorological monitoring station, Dhahran (26°C 32′ N, 50° 13′ E), Saudi Arabia, have been analyzed to investigate the optimum size of battery storage capacity for hybrid (wind+diesel) energy conversion systems at Dhahran. The monthly average wind speeds for Dhahran range from 4.12 to 6.42 m/s. As a case study, the hybrid system considered in the present analysis consists of two 10 kW Wind Energy Conversion Systems (WECS), together with a battery storage system and a diesel back-up. The yearly and monthly average energy generated from the above hybrid system have been presented. More importantly, the study explores the impact of variation of battery storage capacity on hybrid power generation. The results exhibit a trade-off between size of the storage capacity and diesel power to be generated to cope with specific annual load distribution [41,500], and for given energy generation from WECS. The energy to be generated from the back-up diesel generator and the number of operational hours of the diesel system to meet a specific annual electrical energy demand have also been presented. The diesel back-up system is operated at times when the power generated from WECS fails to satisfy the load and when the battery storage is depleted. The present study shows that for economic considerations, for optimum use of battery storage and for optimum operation of diesel system, storage capacity equivalent to one to three days of maximum monthly average daily demand needs to be used. It has been found that the diesel energy to be generated without any storage is considerably high; however, use of one day of battery storage reduces diesel energy generation by about 35%; also the number of hours of operation of the diesel system are reduced by about 52%.     

Review of research on autonomous wind farms and solar parks and their feasibility for commercial loads in hot regions

In the wake of rising cost of oil and fears of its exhaustion coupled with increased pollution, the governments world-wide are deliberating and making huge strides to promote renewable energy sources such as solar–photovoltaic (solar–PV) and wind energy. Integration of diesel systems with hybrid wind–PV systems is pursued widely to reduce dependence on fossil-fuel produced energy and to reduce the release of carbon gases that cause global climate change. Literature indicates that commercial/residential buildings in the Kingdom of Saudi Arabia (KSA) consume an estimated 10–40% of the total electric energy generated. The study reviews research work carried out world-wide on wind farms and solar parks. The work also analyzes wind speed and solar radiation data of East-Coast (Dhahran), KSA, to assess the technical and economic potential of wind farm and solar PV park (hybrid wind–PV–diesel power systems) to meet the load requirements of a typical commercial building (with annual electrical energy demand of 620,000 kWh). The monthly average wind speeds range from 3.3 to 5.6 m/s. The monthly average daily solar global radiation ranges from 3.61 to 7.96 kWh/m². The hybrid systems simulated consist of different combinations of 100 kW wind machines, PV panels, supplemented by diesel generators. NREL (and HOMER Energy's) HOMER software has been used to perform the techno-economic study. The simulation results indicate that for a hybrid system comprising of 100 kW wind capacity (37 m hub-height) and 40 kW of PV capacity together with 175 kW diesel system, the renewable energy fraction (with 0% annual capacity shortage) is 36% (24% wind + 12% PV). The cost of generating energy (COE, $/kWh) from this hybrid wind–PV–diesel system has been found to be 0.154 $/kWh (assuming diesel fuel price of 0.1$/L). The study exhibits that for a given hybrid configuration, the number of operational hours of diesel generators decreases with increase in wind farm and PV capacity. Attention has also been focused on wind/PV penetration, un-met load, excess electricity generation, percentage fuel savings and reduction in carbon emissions (relative to diesel-only situation) of different hybrid systems, cost break-down of wind–PV–diesel systems, COE of different hybrid systems, etc.     

Impact of battery storage on economics of hybrid wind‐diesel power systems in commercial applications in hot regions

Integration of wind machines and battery storage with the diesel plants is pursued widely to reduce dependence on fossil fuels. The aim of this study is to assess the impact of battery storage on the economics of hybrid wind‐diesel power systems in commercial applications by analyzing wind‐speed data of Dhahran, East‐Coast, Kingdom of Saudi Arabia (K.S.A.). The annual load of a typical commercial building is 620,000 kWh. The monthly average wind speeds range from 3.3 to 5.6 m/s. The hybrid systems simulated consist of different combinations of 100‐kW commercial wind machines (CWMs) supplemented with battery storage and diesel generators. National Renewable Energy Laboratory's (NREL's) (HOMER Energy's) Hybrid Optimization Model for Electric Renewables (HOMER) software has been employed to perform the economic analysis. The simulation results indicate that for a hybrid system comprising of 100‐kW wind capacity together with 175‐kW diesel system and a battery storage of 4 h of autonomy (i.e. 4 h of average load), the wind penetration (at 37‐m hub height, with 0% annual capacity shortage) is 25%. The cost of generating energy (COE, $/kWh) from this hybrid wind–battery–diesel system has been found to be 0.139 $/kWh (assuming diesel fuel price of 0.1$/L). The investigation examines the effect of wind/battery penetration on: COE, operational hours of diesel gensets. Emphasis has also been placed on un‐met load, excess electricity, fuel savings and reduction in carbon emissions (for wind–diesel without battery storage, wind–diesel with storage, as compared to diesel‐only situation), cost of wind–battery–diesel systems, COE of different hybrid systems, etc. The study addresses benefits of incorporation of short‐term battery storage (in wind–diesel systems) in terms of fuel savings, diesel operation time, carbon emissions, and excess energy. The percentage fuel savings by using above hybrid system is 27% as compared to diesel‐only situation Copyright © 2012 John Wiley & Sons, Ltd.     

Decentralized/stand-alone hybrid Wind–Diesel power systems to meet residential loads of hot coastal regions

In view of rising costs, pollution and fears of exhaustion of oil and coal, governments around the world are encouraging to seek energy from renewable/sustainable energy sources such as wind. The utilization of energy from wind (since the oil embargo of the 1970s) is being widely disseminated for displacement of fossil fuel produced energy and to reduce atmospheric degradation. A system that consists of a wind turbine and Diesel genset is called a Wind–Diesel power system.The literature indicates that the commercial/residential buildings in Saudi Arabia consume an estimated 10–40% of the total electric energy generated. In the present study, the hourly mean wind-speed data of the period 1986–1997 recorded at the solar radiation and meteorological station, Dhahran (26°32′N, 50°13′E in the Eastern Coastal Region of Saudi Arabia), has been analyzed to investigate the potential of utilizing hybrid (Wind–Diesel) energy conversion systems to meet the load requirements of a hundred typical two bedroom residential buildings (with annual electrical energy demand of 3512 MWh). The long term monthly average wind speeds for Dhahran range from 4.2 to 6.4 m/s. The hybrid systems considered in the present case study consist of different combinations/clusters of 150 kW commercial wind machines supplemented with battery storage and Diesel back-up. The deficit energy generated by the Diesel generator (for different battery capacities) and the number of operational hours of the Diesel system to meet a specific annual electrical energy demand of 3512 MWh have also been presented. The evaluation of the hybrid system shows that with seven 150 kW wind energy conversion system (WECS) and one day of battery storage, the Diesel back-up system has to provide 21.6% of the load demand. Furthermore, with three days of battery storage, the Diesel back-up system has to provide 17.5% of the load demand. However, in the absence of battery storage, about 37% of the load needs to be provided by the Diesel system. The study also places emphasis on the monthly average daily energy generation from different sizes (150 kW, 250 kW, 600 kW) of wind machines to identify the optimum wind machine size from the energy production point of view. It has been noted that for a given 6 MW wind farm size (for 50 m hub height), a cluster of forty 150 kW wind machines yields about 48% more energy as compared to a cluster of ten 600 kW wind machines.     

Techno-economic evaluation of off-grid hybrid photovoltaic–diesel–battery power systems for rural electrification in Saudi Arabia—A way forward for sustainable development

The burning of depleting fossil fuels for power generation has detrimental impact on human life and climate. In view of this, renewable solar energy sources are being increasingly exploited to meet the energy needs. Moreover, solar photovoltaic (PV)–diesel hybrid system technology promises lot of opportunities in remote areas which are far from utility grid and are driven by diesel generators. Integration of PV systems with the diesel plants is being disseminated worldwide to reduce diesel fuel consumption and to minimize atmospheric pollution. The Kingdom of Saudi Arabia (K.S.A.) being endowed with high intensity of solar radiation, is a prospective candidate for deployment of PV systems. Also, K.S.A. has large number of remote scattered villages. The aim of this study is to analyze solar radiation data of Rafha, K.S.A., to assess the techno-economic feasibility of hybrid PV–diesel–battery power systems to meet the load requirements of a typical remote village Rawdhat Bin Habbas (RBH) with annual electrical energy demand of 15,943 MWh. Rafha is located near RBH. The monthly average daily global solar radiation ranges from 3.04 to 7.3 kWh/m². NREL's HOMER software has been used to perform the techno-economic evaluation. The simulation results indicate that for a hybrid system composed of 2.5 MWp capacity PV system together with 4.5 MW diesel system (three 1.5 MW units) and a battery storage of 1 h of autonomy (equivalent to 1 h of average load), the PV penetration is 27%. The cost of generating energy (COE, US$/kWh) from the above hybrid system has been found to be 0.170$/kWh (assuming diesel fuel price of 0.1$/l). The study exhibits that the operational hours of diesel generators decrease with increase in PV capacity. The investigation also examines the effect of PV/battery penetration on COE, operational hours of diesel gensets. Concurrently, emphasis has been placed on: un-met load, excess electricity generation, percentage fuel savings and reduction in carbon emissions (for different scenarios such as: PV–diesel without storage, PV–diesel with storage, as compared to diesel-only situation), COE of different hybrid systems, etc. The decrease in carbon emissions by using the above hybrid system is about 24% as compared to the diesel-only scenario.     

Diffuse fraction of daily global radiation at Dhahran, Saudi Arabia

Relationship between the diffuse fraction of daily global solar radiation and clearness index (the ratio of global to extraterrestrial radiation) is obtained from the radiation data measured at Dhahran (26°32′N, 50°13′E), Saudi Arabia. Two years of daily radiation data calculated from measured one-minute values are used to develop the relationship. Another year of data is used to validate the relationship. Comparison between the present correlation and previous correlations is presented. The present data confirm the seasonal dependence and the location independence of the correlation reported in literature. The diffuse and global solar radiation are presented for dusty and clear days. The results show that the dust significantly increases the diffuse fraction of the global radiation. The diffuse fraction on a typical clear day in March is 0.11, while on a dusty day, in the same month, may be as high as 0.91.     

Technical and economic assessment of grid-independent hybrid photovoltaic–diesel–battery power systems for commercial loads in desert environments

Solar photovoltaic (PV) hybrid system technology is a hot topic for R&D since it promises lot of challenges and opportunities for developed and developing countries. The Kingdom of Saudi Arabia (KSA) being endowed with fairly high degree of solar radiation is a potential candidate for deployment of PV systems for power generation. Literature indicates that commercial/residential buildings in KSA consume an estimated 10–45% of the total electric energy generated. In the present study, solar radiation data of Dhahran (East-Coast, KSA) have been analyzed to assess the techno-economic viability of utilizing hybrid PV–diesel–battery power systems to meet the load requirements of a typical commercial building (with annual electrical energy demand of 620,000 kW h). The monthly average daily solar global radiation ranges from 3.61 to 7.96 kW h/m². NREL's HOMER software has been used to carry out the techno-economic viability. The simulation results indicate that for a hybrid system comprising of 80 kWp PV system together with 175 kW diesel system and a battery storage of 3 h of autonomy (equivalent to 3 h of average load), the PV penetration is 26%. The cost of generating energy (COE, US$/kW h) from the above hybrid system has been found to be 0.149 $/kW h (assuming diesel fuel price of 0.1 $/L). The study exhibits that for a given hybrid configuration, the operational hours of diesel generators decrease with increase in PV capacity. The investigation also examines the effect of PV/battery penetration on COE, operational hours of diesel gensets for a given hybrid system. Emphasis has also been placed on unmet load, excess electricity generation, percentage fuel savings and reduction in carbon emissions (for different scenarios such as PV–diesel without storage, PV–diesel with storage, as compared to diesel-only situation), cost of PV–diesel–battery systems, COE of different hybrid systems, etc.     

Economic perspective of PV electricity in Oman

Solar and wind energies are likely to play an important role in the future energy generation in Oman. This paper utilizes average daily global solar radiation and sunshine duration data of 25 locations in Oman to study the economic prospects of solar energy. The study considers a solar PV power plant of 5-MW at each of the 25 locations. The global solar radiation varies between slightly greater than 4 kWh/m²/day at Sur to about 6 kWh/m²/day at Marmul while the average value in the 25 locations is more than 5 kWh/m²/day. The results show that the renewable energy produced each year from the PV power plant varies between 9000 MWh at Marmul and 6200 MWh at Sur while the mean value is 7700 MWh of all the 25 locations. The capacity factor of PV plant varies between 20% and 14% and the cost of electricity varies between 210 US$/MWh and 304 US$/MWh for the best location to the least attractive location, respectively. The study has also found that the PV energy at the best location is competitive with diesel generation without including the externality costs of diesel. Renewable energy support policies that can be implemented in Oman are also discussed.     

Modelling of solar/diesel/battery hybrid power systems for far-north Cameroon

Solar/diesel/battery hybrid power systems have been modelled for the electrification of typical rural households and schools in remote areas of the far north province of Cameroon. The hourly solar radiation received by latitude-titled and south-facing modules was computed from hourly global horizontal solar radiation of Garoua using Hay's anisotropic model. Using the solar radiation computed for latitude-tilted and south-facing modules, the average daytime temperatures for Garoua and parameters of selected solar modules, the monthly energy production of the solar modules was computed. It was found that BP solar modules with rated power in the range 50–180 Wp produced energy in the range 78.5–315.2 kWh/yr. The energy produced by the solar modules was used to model solar/diesel/battery hybrid power systems that could meet the energy demand of typical rural households in the range 70–300 kWh/yr. It was also found that a solar/diesel/battery hybrid power system comprising a 1440 Wp solar array and a 5 kW single-phase generator operating at a load factor of 70%, required only 136 generator h/yr to supply 2585 kWh/yr or 7 kWh/day to a typical secondary school. The renewable energy fraction obtained in all the systems evaluated was in the range 83–100%. These results show that there is a possibility to increase the access rate to electricity in the far north province without recourse to grid extension or more thermal plants in the northern grid or more independent diesel plants supplying power to remote areas of the province.     

A computer study for estimation of seasonal energy consumption and selection of air-conditioner in six Saudi Arabian cities

A computer model was developed to simulate the building cooling load and the seasonal energy consumption of standard residential sized central air-conditioning systems. The model was first validated by comparing the predicted cooling energy consumption against the metered energy of a 100 m² residence. The model predicts within 10% of the metered value. The validated model was next used to compute the cooling load and seasonal energy consumption for similar 100 m² residences in six cities located in different climatic zones of Saudi Arabia. Simulations showed that the cities of Dhahran and Riyadh required a 17.6 kW system to satisfy the cooling load through the year, whereas the defined residences in the cities of Taif, Hail, Jeddah and Gizan required a 14.1 kW system. Our analysis showed that the selected residence in Gizan would consume 23,100 kWh annually, while a comparable residence located in Dhahran, having a more severe summer, required only 21,500 kWh. This difference may be explained by analysis of the weather data which revealed that Gizan required year-round cooling, whereas Dhahran needed cooling for only 283 days during the year. Investigation showed that, by selecting the next smaller capacity air-conditioning unit for each location than required to satisfy the load for 100% of the time, the annual power consumption may be reduced, on an average, by 10%, with about 7% of the hours during the cooling season when the air-conditioning load may not be satisfied.     

Wind energy potential at Palkalainagar

This paper uses the Weibull's distribution function to describe the wind speed frequency distribution at Palkalainagar (geographical co-ordinates N : 9°54′, E : 78°54′), Madurai, India using the one year data available. Weibull's parameters are used to estimate the wind data parameters for the site. Of the wind data parameters the most important one is the annual specific output (T_A). This is used in determining the annual energy output of a Wind Energy Conversion System (WECS) and in conducting cost-benefit analysis of wind-electricity generation. The parameter is used in evaluating the efficiency of WECS in the same site. Results show the possibilities of harnessing wind energy towards electricity generation.     

Wind power cost assessment at twenty locations in the kingdom of Saudi Arabia

The Kingdom of Saudi Arabia has vast open land and hence has great potential of harnessing solar and wind energy sources for domestic and industrial use. This study proposes to assess wind power cost per kWh of electricity produced using three types of wind electric conversion systems at 20 locations within the Kingdom. These sites cover the eastern, central, and western regions. Hourly values of wind speed recorded for periods of 5.5–13 years (between 1970–1982, in most cases) were used for all 20 locations. Wind duration curves were developed and utilized to calculate the cost per kWh of electricity generated from three chosen wind-machines.     

Design and implementation of wind energy system in Saudi Arabia

This paper introduces an accurate procedure to choose the best site from many sites and suitable wind turbines for these sites depending on the minimum price of kWh generated (Energy Cost Figure (ECF)) from wind energy system. In this paper a new proposed computer program has been introduced to perform all the calculations and optimization required to accurately design the wind energy system and matching between sites and wind turbines. Some of cost calculations of energy methods have been introduced and compared to choose the most suitable method. The data for five sites in Saudi Arabia and hundred wind turbines have been used to choose the best site and the optimum wind turbine for each site. These sites are Yanbo, Dhahran, Dhulom, Riyadh, and Qaisumah. One hundred wind turbines have been used to choose the best one for each site. This program is built in a generic form which allows it to be used with unlimited number of sites and wind turbines in all over the world. The program is written by using Visual Fortran and it is verified with simple calculation in Excel. The paper showed that the best site is Dhahran and the suitable wind turbine for this site is KMW-ERNO with 5.85 Cents/kWh. The worst site to install wind energy system is Riyadh with minimum price of kWh of 12.81 Cents/kWh in case of using GE Energy 2 wind turbine.     

DESIGN OF HYBRID-PHOTOVOLTAIC POWER GENERATOR, WITH OPTIMIZATION OF ENERGY MANAGEMENT

A methodology is developed for calculating the correct size of a photovoltaic (PV)-hybrid system and for optimizing its management. The power for the hybrid system comes from PV panels and an engine-generator – that is, a gasoline or diesel engine driving an electrical generator. The combined system is a stand-alone or autonomous system, in the sense that no third energy source is brought in to meet the load. Two parameters were used to characterize the role of the engine-generator: denoted SDM and SAR, they are, respectively, the battery charge threshold at which it is started up, and the storage capacity threshold at which it is stopped, both expressed as a percentage of the nominal battery storage capacity. The methodology developed is applied to designing a PV-hybrid system operating in Corsica, as a case study. Various sizing configurations were simulated, and the optimal configuration that meets the autonomy constraint (no loss of load) was determined, by minimizing of the energy cost. The influence of the battery storage capacity on the solar contribution is also studied. The smallest energy cost per kWh was obtained for a system characterized by an SDM=30% and an SAR=70%. A study on the effects of component lifetimes on the economics of PV-hybrid and PV stand-alone systems has shown that battery size can be reduced by a factor of two in PV-hybrid systems, as compared to PV stand-alone systems.     

Performance analysis of various hybrid renewable energy systems using battery,hydrogen, and pumped hydro‐based storage units

The aim of this research is to analyze the techno‐economic performance of hybrid renewable energy system (HRES) using batteries, pumped hydro‐based, and hydrogen‐based storage units at Sharurah, Saudi Arabia. The simulations and optimization process are carried out for nine HRES scenarios to determine the optimum sizes of components for each scenario. The optimal sizing of components for each HRES scenario is determined based on the net present cost (NPC) optimization criterion. All of the nine optimized HRES scenarios are then evaluated based on NPC, levelized cost of energy, payback period, CO₂ emissions, excess electricity, and renewable energy fraction. The simulation results show that the photovoltaic (PV)‐diesel‐battery scenario is economically the most viable system with the NPC of US$2.70 million and levelized cost of energy of US$0.178/kWh. Conversely, PV‐diesel‐fuel cell system is proved to be economically the least feasible system. Moreover, the wind‐diesel‐fuel cell is the most economical scenario in the hydrogen‐based storage category. PV‐wind‐diesel‐pumped hydro scenario has the highest renewable energy fraction of 89.8%. PV‐wind‐diesel‐pumped hydro scenario is the most environment‐friendly system, with an 89% reduction in CO₂ emissions compared with the base‐case diesel only scenario. Overall, the systems with battery and pumped hydro storage options have shown better techno‐economic performance compared with the systems with hydrogen‐based storage.