Stand-alone Renewable Energy System Research Articles

Amorphous FeSnOx Nanosheets with Hierarchical Vacancies for Room-Temperature Sodium-Sulfur Batteries.

Room-temperature sodium-sulfur (RT Na-S) batteries, noted for their low material costs and high energy density, are emerging as a promising alternative to lithium-ion batteries (LIBs) in various applications including power grids and standalone renewable energy systems. These batteries are commonly assembled with glass fiber membranes, which face significant challenges like the dissolution of polysulfides, sluggish sulfur conversion kinetics, and the growth of Na dendrites. Here, we develop an amorphous two-dimensional (2D) iron tin oxide (A-FeSnOx) nanosheet with hierarchical vacancies, including abundant oxygen vacancies (Ovs) and nano-sized perforations, that can be assembled into a multifunctional layer overlaying commercial separators for RT Na-S batteries. The Ovs offer strong adsorption and abundant catalytic sites for polysulfides, while the defect concentration is finely tuned to elucidate the polysulfides conversion mechanisms. The nano-sized perforations aid in regulating Na ions transport, resulting in uniform Na deposition. Moreover, the strategic addition of trace amounts of Ti3C2 (MXene) forms an amorphous/crystalline (A/C) interface that significantly improves the mechanical properties of the separator and suppresses dendrite growth. As a result, the task-specific layer achieves ultra-light (~0.1 mg cm-2), ultra-thin (~200 nm), and ultra-robust (modulus=4.9 GPa) characteristics. Consequently, the RT Na-S battery maintained a high capacity of 610.3 mAh g-1 and an average Coulombic efficiency of 99.9 % after 400 cycles at 0.5 C.

Amorphous FeSnOx Nanosheets with Hierarchical Vacancies for Room‐Temperature Sodium‐Sulfur Batteries

AbstractRoom‐temperature sodium‐sulfur (RT Na−S) batteries, noted for their low material costs and high energy density, are emerging as a promising alternative to lithium‐ion batteries (LIBs) in various applications including power grids and standalone renewable energy systems. These batteries are commonly assembled with glass fiber membranes, which face significant challenges like the dissolution of polysulfides, sluggish sulfur conversion kinetics, and the growth of Na dendrites. Here, we develop an amorphous two‐dimensional (2D) iron tin oxide (A‐FeSnOx) nanosheet with hierarchical vacancies, including abundant oxygen vacancies (Ovs) and nano‐sized perforations, that can be assembled into a multifunctional layer overlaying commercial separators for RT Na−S batteries. The Ovs offer strong adsorption and abundant catalytic sites for polysulfides, while the defect concentration is finely tuned to elucidate the polysulfides conversion mechanisms. The nano‐sized perforations aid in regulating Na ions transport, resulting in uniform Na deposition. Moreover, the strategic addition of trace amounts of Ti3C2 (MXene) forms an amorphous/crystalline (A/C) interface that significantly improves the mechanical properties of the separator and suppresses dendrite growth. As a result, the task‐specific layer achieves ultra‐light (~0.1 mg cm−2), ultra‐thin (~200 nm), and ultra‐robust (modulus=4.9 GPa) characteristics. Consequently, the RT Na−S battery maintained a high capacity of 610.3 mAh g−1 and an average Coulombic efficiency of 99.9 % after 400 cycles at 0.5 C.

Collective hydrogen stand-alone renewable energy systems for buildings in Spain. Towards the self-sufficiency

The article examines the feasibility of implementing standalone hydrogen-based renewable energy systems in Spanish residential buildings, specifically analyzing the optimization of a solar-battery and solar-hydrogen system for a building with 20 dwellings in Spain. The study initially assesses two standalone setups: solar-battery and solar-hydrogen. Subsequently, it explores scenarios where these systems are connected to the grid to only generate and sell surplus energy. A scenario involving grid connection for self-consumption without storage serves as a benchmark for comparison. All system optimizations are designed to meet energy demands without interruptions while minimizing costs, as determined by a techno-economic analysis. The systems are sized using custom software that incorporates an energy management system and employs the Jaya algorithm for optimization. The findings indicate that selling surplus energy can be economically competitive and enhance the efficiency of grid-connected self-consumption systems, representing the study's main innovation. The conclusion highlights the economic and technical potential of an autonomous hybrid energy system that includes hydrogen, with the significant remaining challenge being the development of a regulatory framework to support its technical feasibility in Spain.

Forecast-based stochastic optimization for a load powered by wave energy

Stand-alone renewable energy systems, which harness and use electricity without connection to a distribution grid, can benefit from using resource forecasts when making real-time decisions on how to manage power. An example of this is an ocean observation system that uses a wave energy converter (WEC) and battery bank to produce and store electricity in order to meet electrical load requirements for oceanographic sensors and instrumentation. By using wave forecasts to optimize the power consumption of this system, it is possible to reduce the size of the WEC and battery bank needed, thereby reducing the overall system’s cost and complexity. In this paper, we assess the benefits of forecasting for a generic wave-powered ocean observation system. We model an observation platform powered by a WEC and battery-storage system that can switch between four power states, full power: 600 W, medium power: 450 W, low power: 45 W, and survival mode: 1 W. To determine which power state to enter over time, we present a stochastic optimization method that interprets wave forecasts and system information to select a power state on an hourly basis and simulate over two months of consecutive decisions. Using this simulation framework, we compare 8 power management strategies across a range of WEC sizes (3–5 m) and battery capacities (2.5–35 kWh). We find that it is possible to maintain full (600 W) power consumption over the entire simulation window with a 5 m diameter WEC and 25 kWh battery bank, which is on the upper end of the ranges evaluated. To employ a smaller WEC or battery, load flexibility is required. We find that forecast-based methods for this power management handle tradeoffs in performance (e.g., cumulative power consumption, reducing intermittencies and meeting scheduled load targets) more effectively than power management strategies that do not use forecasting. Overall, our results indicate that forecasting for our stand-alone renewable energy system is most impactful when some loads must be met on or within a defined schedule.

Multi-objective and multi-criteria decision making for Technoeconomic optimum design of hybrid standalone renewable energy system

The major obstacle in designing of the wind turbine/photovoltaic/battery storage system lies in the task of choosing the most optimum solution while simultaneously considering techno-economic objectives. Consequently, this study provides a distinctive amalgamation of multi-objective multi-perspective and group multi-criteria decision-making methodologies to ascertain collections of Pareto optimum configurations and to weight, rank, and pick up the most desirable optimum solutions that represent best trade-off between conflicting objectives. In this paper, the multi-objective Dragon fly algorithm is developed based on mutation scheme and crossover tactic algorithm is advanced to handle a lack of diversity and poor convergence, while non-dominated sorting and crowding distance strategy is addressed to store the best found optimum solutions in the achieve. Loss of load probability, excess energy, and life cycle cost are conflicting techno-economic objectives solved by multi-objective method. The optimum Pareto front solutions are ranked based on hybrid multi-criteria decision-making method for determining the most favorable solution for the WT/PV/BS system. The experimental outcomes indicated that the developed approach has a distinct performance in constructing a collection of Pareto front solutions in terms of diversity, converge, and convergence. Moreover, it demonstrates outstanding results when compared to well-organized multi-objective optimization methods. The future direction can be accomplished by applying the proposed hybrid sizing methodology for solving gird-connected system along with electric vehicle based on techno-economic scenarios.

Optimal Power Flow Management for a Solar PV-Powered Soldier-Level Pico-Grid

Users ought to decide how to operate and manage power systems in order to achieve various goals. As a result, many strategies have been developed to aid in this regard. Optimal power flow management is one such strategy that assists users in properly operating and managing the supply and demand of power in an optimal way under specified constraints. However, in-depth research on optimal power flow management is yet to be explored when it comes to the supply and demand of power for the bulk of standalone renewable energy systems such as solar photovoltaics, especially when it comes to specific applications such as powering military soldier-level portable electronic devices. This paper presents an optimal power flow management modelling and optimisation approach for solar-powered soldier-level portable electronic devices. The OPTI toolbox in MATLAB is used to solve the formulated nonlinear optimal power flow management problem using SCIP as the solver. A globally optimal solution was arrived at in a case study in which the objective function was to minimise the difference between the power supplied to the portable electronic device electronics and the respective portable electronic device power demands. This ensured that the demand for solar-powered soldier-level portable electronic devices is met at all times in spite of the prohibitive case scenarios’ circumstances under the given constraints. This resolute approach underscores the importance placed on satisfying the demand needs of the specific devices while navigating and addressing the limitations posed by the existing conditions or constraints. Soldiers and the solar photovoltaic user fraternity at large will benefit from this work as they will be guided on how to optimally manage their power systems’ supply and demand scenarios. The model developed herein is applicable to any demand profile and any number of portable electronic device and is adaptable to any geographical location receiving any amount of solar radiation.

Can renewable energy work for rural societies? Exploring productive use, institutions, support systems, and trust for solar electricity in the Navajo Nation

Reliable electricity and water access remain major challenges in rural communities worldwide. Standalone renewable energy systems show promise in improving access, but successful long-term outcomes remain infrequent in practice. To achieve sustainable outcomes, planners and decision makers should place a greater emphasis on understanding community context to determine the technological and social appropriacy of renewable energy technology. This article investigates a case study of renewable energy systems in the Navajo Nation to develop an understanding of what technical and social considerations may be necessary. A qualitative exploratory data analysis approach is used to perform a comparative analysis of two programs that deployed solar home systems (SHS) and atmospheric water generation (AWG) systems to address electricity and water needs in the Nation, respectively. The findings reveal that renewable energy programs should critically evaluate four factors related to technological and procedural appropriacy. These four factors are (1) an understanding of the productive use of the technology in context, (2) the need to operate within extant institutional paradigms, (3) the capacity to develop and maintain a support network, and (4) the need for trust building. The findings indicate that productive use of renewable energy is determined by end-user application and its usefulness in the community’s rank order of priorities. It also demonstrates that social acceptance of renewable energy is affected by the willingness of programs to conform to existing institutional paradigms. This article refines and expands upon existing themes of social acceptance, making them more application oriented by focusing on the planning phase.

Performance investigation of a standalone renewable energy system using response surface methodology (RSM): 4E analysis and multi-objective optimization

This study aimed to identify and present novel findings in the field of hybrid renewable energy systems tailored for off-grid operation through a numerical-experimental investigation. The objective of the research was to contribute to the current knowledge of energy systems by addressing critical aspects of energy, exergy, economic, and environmental (4E) evaluations. The system described in the study is designed to meet the electricity demands of a telecom tower by integrating various components, including a photovoltaic (PV) unit, proton exchange membrane electrolyzer (PEME), proton exchange membrane fuel cell (PEMFC), and battery storage unit. An organic Rankine cycle (ORC) is also incorporated to efficiently recover waste heat from the PEMFC. The PV unit serves as the primary power source, with excess solar power directed to the PEME during periods of high solar irradiation. The PEME generates hydrogen and oxygen, while the PEMFC is fueled by hydrogen stored in metal hydride tanks. This setup ensures consistent power generation year-round. The study employs response surface methodology (RSM) to create regression equation models and utilizes the desirability function approach for multi-objective optimization. The optimal parameters identified include a 12:35 PM time setting, PEMFC current density of 0.693 A/cm2, PEME inlet water temperature of 326.2 K, and ORC turbine inlet pressure of around 580 kPa. These parameters result in impressive 4E outcomes: 50.9 % energy efficiency, 54.7 % exergy efficiency, a $0.53 levelized cost of energy, and a sustainability index of 2.1.

Exergetic assessment of an solar powered stand-alone system using liquid organic hydrogen carrier for energy storage

The integration of energy storage technologies into renewable energy systems has gained increasing attention for continuous supply of the renewable-based enegy. Among different storage alternatives, the use of a Liquid Organic Hydrogen Carrier (LOHC) has a significant potential as a reversible energy carrier for short and long-term energy storage. In this study, the technical and economic performance of an stand-alone renewable energy systems using a LOHC for energy storage have been evaluated by exergy-based methods in addition to simple energy and economic analysis. The analysis of the LOHC-free system was also included to determine the effect of LOHC on the system performance. The system containing phovoltaic (PV) panels, an electrolyzer, a micro gas turbine and hydrogenation/dehydrogenation LOHC units was designed to meet the power, heating and cooling requirement of a residential building. The system modelling and performance evaluation were made by using TRNSYS and EES softwares. Results show that the LOHC-containing system has higher energy and exergy efficiencies and exergoeconomic performance than the LOHC-free system while the latter is economically more feasible than the former due to its low capital investment cost.

Techno-economic feasibility and performance analysis of an islanded hybrid renewable energy system with hydrogen storage in Morocco

This study focuses on the conceptual design and viability assessment of a hybrid microgrid system for a settlement in Dakhla city. The system consists of a 600 kW wind turbine, 300 kW diesel generators for backup, a 300 kW fuel cell, and a 500 kW electrolyzer. A simulation model using TRNSYS software was developed to analyze the energy exchange and ensure system reliability. The study incorporates a power dispatch management strategy (PDMS) with load following mode (LFM) and cycle charging mode (CCM) approaches, aiming to enhance the understanding and management of stand-alone renewable energy systems with electrochemical storage. A techno-economic investigation is conducted for a settlement load profile using the hybrid wind/Fuel/DEGS configuration to evaluate its feasibility. The performance study reveals that the hybrid system achieves a significant renewable fraction of 44.57 %. From an economic perspective, the proposed hybrid system proves to be financially viable. The analysis shows an NPVCost of $2,650,843 and NPVProduction of 37,819,172 kWh, resulting in a levelized energy cost of $0.0701/kWh. Additionally, the system demonstrates the potential to reduce CO2 emissions by 70,529.80 tons over its 20-year lifespan, with a carbon reduction cost of approximately $37.5847 per t/CO2e. These findings highlight the substantial cost savings of approximately $2,656,754.51, equivalent to the creation of 5256.16 acres or 2125.7 ha of new green space and plants. The combination of economic viability and environmental benefits positions the proposed hybrid energy system as a promising alternative for meeting long-term energy needs while mitigating environmental impact. The study underscores the potential of the system to provide cost-effective electricity to remote communities, thereby contributing to addressing the energy crisis and fostering a sustainable future. The proposed hybrid energy system has significant potential to provide electricity to remote communities at low production costs, as well as to contribute to preventing, controlling, and overcoming the energy crisis for a sustainable future.

Energy Management and Optimization of a Standalone Renewable Energy System in Rural Areas of the Najran Province

Electricity demand is increased due to the exponential rise in consumption in the residential, industrial, and transportation sectors as the human comfort level increases with each passing year. Most countries rely on conventional fuels, especially natural gas, to fulfill their energy demand, which increases the risk of reservoir depletion of conventional fuels. In this regard, the adoption of energy generation through free and environment-friendly renewable energy resources such as wind turbines and solar photovoltaics is increasing rapidly. However, the fluctuating and intermittent nature of renewable resources requires the integration of advanced control mechanisms and power electronics to ensure power quality and system resilience towards disturbances. Standalone microgrids comprising renewable source-based distributed generation systems are becoming the ideal solution to fulfill the need for decentralized small residential communities. This research work focuses on the optimal design and techno-economic analysis of a standalone microgrid for a small residential community in Sharurah City in the Kingdom of Saudi Arabia. HOMER Pro and MATLAB/Simulink have been used for the optimal design of microgrids and energy management using intelligence-based control mechanisms in between generation and load, respectively. The electricity price obtained from the optimized microgrid system is 0.18 SAR/kWh, which is quite low in comparison to generation through a base system (0.38 SAR/kWh) and a diesel generator, respectively. A simulation of the optimized system was modeled and verified using MATLAB/Simulink. The obtained results show the robustness of the presented system against the change in load demand and meteorological conditions.

Three-Port Forward Converters With Compact Structure and Extended Duty Cycle Range

A series of three-port forward converters with a compact structure and extended duty cycle range is presented for the standalone renewable energy system. Bidirectional power-flow port embedding and switch device sharing can be used to derive these converters from conventional two-switches forward converters. In comparison to the conventional two-switch forward converter, only one switch and one diode are added to build an energy storage port with bidirectional power flow characteristics, which has the benefits of compact structure and low cost. Meanwhile, the embedding of the energy storage port provides an additional demagnetization loop for the magnetic inductor, which extends the duty cycle range of the forward converter so that the proposed converter no longer requires a duty cycle of less than 0.5 as in the case of conventional forward converters. The proposed converters also offer the advantages of fewer components, easy control, and independent control of power flow between multiple ports when compared to similar solutions. Finally, an experimental setup with a photovoltaic battery as an application is developed, and the experimental results verify the effectiveness and flexibility of the proposed topology and control method.

Application and effect analysis of renewable energy in a small standalone automatic observation system deployed in the polar regions

Considering the difficulty of power supply for automatic observation equipment in the polar regions, this paper introduced a small standalone renewable energy system with wind–solar co-generation as the energy supply scheme. Mathematical models were given, including solar photovoltaic panels, wind turbines, solar irradiance, wind energy density, and renewable energy assessment. ERA-Interim atmospheric reanalysis data were used to evaluate solar energy resources, and the synergistic effect of wind–solar resources on renewable energy was also analyzed and discussed. The system composition of the small standalone renewable energy system was proposed in this study. This system deployed near Zhongshan Station was taken as the object of investigation to analyze the operation performance of each component of the system in different months, and the technical feasibility of the system has also been verified. The results showed that the wind–solar resources in the polar regions had a synergistic effect, which can provide an effective and feasible scheme for the power supply of automatic observation equipment. Through research and analysis, it was found that each component of the renewable energy system, including photovoltaic panels, wind turbines, and batteries, could meet the long-term power supply requirements of automatic observation regardless of the polar periods, polar day or polar night. This paper can not only provide theoretical and data support for the application of small independent renewable energy systems in the polar regions but also provide feasible solutions for clean energy supply of the systems and equipment for independent observation stations deployed in uninhabited islands and alpine regions.

Case study on demand side management‐based cost optimized battery integrated hybrid renewable energy system for remote rural electrification

AbstractPower demand of isolated villages where on‐grid power supply is not economical can be met by standalone renewable energy system. Hybrid renewable energy system (HRES) considered in the current study involves photo‐voltaic, wind turbine, diesel generator, and battery. In the present study, the demand side energy management methods are used for energy management. The load shifting and strategic conservation methods are used. The energy management schemes are applied in the stage of load estimation. It is observed in the analysis that, the net present cost (NPC) of $55 263 is reduced to $34 009 with the application of demand side energy management strategies. The two control strategies, load‐following and predictive‐dispatch strategy are incorporated. The three types of batteries like lead‐acid, lithium‐ion, and zinc‐bromide are integrated, one at a time, for analysis. The analysis results in the optimal HRES configuration solution with the combination of both load shifting and strategic conservation techniques of demand side energy management. The NPC is reduced by 37% in comparison with the HRES without the application of energy management methods. The zinc‐bromide battery integrated HRES configuration through predictive dispatch control strategy with the application of demand side energy management schemes results in optimal solution for electrification of cluster of villages located in Uralagallu panchayat, Sagar Taluk, Shivamogga District, Karnataka, India. To the similar kind of geographical condition areas, the same HRES configuration with similar approach can be extended for electrification.

Electric vehicles development in Sub-Saharan Africa: Performance assessment of standalone renewable energy systems for hydrogen refuelling and electricity charging stations (HRECS)

One of the main setbacks to electric vehicles (EVs) adoption relates to the unavailability of the required charging stations across a jurisdiction. In addition, drawing the required energy of the EVs from a fossil fuel-dominated grid does not only minimize the cleaner benefits of EVs but also puts enormous pressure on an already stressed grid network in electricity-deficient regions like Sub-Saharan Africa (SSA). Hence, in the current study, six different 100% hybrid renewable energy systems based on powerplants of solar, wind, and biomass have been proposed for meeting the energy needs of 70 and 30 battery and fuel cell electric vehicles, respectively using Ghana as a case study. With the aid of HOMER Pro software and multicriteria decision-making tools, the hybrid system, biogas generator-photovoltaic emerged as the most feasible of the six proposed solutions from a technical, economic, and environmental standpoint. This winning system produces 3.9 GWh/yr and 55.6 tonnes/yr of electricity and hydrogen, respectively. The NPC, LCOE, LCOH, and payback period was recorded as $6.53 million, $0.52/kWh, $9.09/kg and ∼8 years, respectively. Approximately, 4 tonnes of GHG emissions are produced by the HRECS each year, and the amount of CO2 emissions avoided from replacing 100 gasoline vehicles with the proposed EVs has been obtained as 460 tons/yr. With the aid of sensitivity analysis, it became apparent that the feasibility of the proposed systems could improve with improvement in components' efficiencies and lifetime, and reduction in unit costs. The current work has several contributions to the sustainable development goals (7, 8, 11, 13), and could aid in accelerating EV penetration in SSA.

A Novel Method for Optimal Calculation of Stand-alone Renewable Energy Systems

Nowadays, the development and use of clean energy sources are receiving strong attention all over the world. However, the current methods used to calculate the design of these systems have proved unconvincing when the optimization is performed by "soft" optimization, and there are certain defects. In this paper, a new method for more robust optimization of independent renewable energy systems is proposed, in which the essential elements of the system such as energy characteristics are obtained in the reality of renewable energy generators or weather changes over time of the year are also considered to solve the problem of optimizing the energy system more efficiently, meet the demand for efficient energy use and optimize consumer investment costs.

Optimal Sizing of Standalone PV-Wind Hybrid Energy System in Rural Area North Egypt

This paper studies the sizing of stand-alone renewable energy system applied in rural areas in the north of Egypt. The available renewable energy sources in these areas are investigated to be integrated to supply the different types of electrical loads. The quality and quantity of these sources over various weather and climate changes are studied to construct a robust energy system. The load demand in such areas is determined according to all activities require electrical energy. This study considers the different economic levels and technologies which affect the load demand value. The technique and economical indices required to obtain the optimal are investigated and applied in the various estimated cases. The genetic algorithm (GA) technique is applied to determine the size and number of photovoltaic panels and wind turbines. The obtained solution takes into account the loss of power supply probability and the minimization of system cost. This study presents an essential phase in the sustainable development of such rural areas.

Two-stage configuration optimization of a novel standalone renewable integrated energy system coupled with hydrogen refueling

Two-stage optimization framework of a novel hybrid renewable integrated energy system is proposed. Firstly, system topological structure and corresponding behaviors are constructed. In this system, renewable energy and conventional thermal power satisfy electricity, heating and cooling demands of the system, and hydrogen storage subsystem is extended for heavy-load fuel cell vehicle refueling. Next, a multi-objective model is constructed to minimize life-time cost of comprehensive loads (LCCL), energy externality rate (EER), and hydrogen hiatus rate (HHR). As for model solution stage, Kernel functions are applied to create typical day scenarios, which contain uncertain information and profoundly ease computational difficulty. Enhanced particle swarm optimization algorithm based on immune clone concept is applied to search non-inferior solutions. Additionally, preference of decision-makers is expanded in solution selection stage that includes more than objectives in the first stage. In the second stage, best Worst Method and Multi-attributive Border Approximation Area Comparison are applied to determine the optimal alternative that corresponds with subjective preference the best. To validate the model, a case in Datong city, Shanxi province in China is selected to validate the framework. Optimization result shows good performance, with LCCL 2.31 Yuan/kWh, EER 6.66%, and HHR 1.09%. Moreover, scenario analysis shows that 1) preference of decision-makers could dramatically influence the ideal solution; 2) double hydrogen refueling demands could be ensured. 3) solar photovoltaic alone could also support the system in Datong. 4) current carbon trade policy almost does not influence the system.

A novel economic method of battery modeling in stand-alone renewable energy systems to reduce life cycle costs

Since the main part of a stand-alone Renewable Energy System (RES) is related to the battery, effective means of reducing the energy ‎mismatch between generation and demand could be obtained using such devices. But with the advent of new types of batteries with unique capabilities, choosing the right type of battery used in stand-alone RESs, in terms of technical and economic components including battery life costs, operation costs, and repair and maintenance costs, has become a very important issue. This research tries a significant step forward since previous conducted researches on ‎storage systems are based on oversimplified economic battery models, considering the impact of power generation and consumption, as well as the impact of battery lifetime on battery lifetime-related costs. Considering the battery lifetime feature, multi-objective optimization has been provided to minimize the costs and maximize the useful lifetime of the system through the Teaching-learning-based optimization (TLBO) algorithm. Technical and economic analysis shows that the generation cost of each scattered product varies according to the type of battery optimization and with increasing system useful life, the TCPDBES index system increases. The results illustrate that the battery type selection varies according to the grid-independent lifetime and the ‎use of Lithium-ion battery, Gel Lead Acid battery, and AGM (Absorbent Glass Mat) Lead Acid types has the minimum energy storage cost for 15, 10, and 5 year lifetimes, respectively.‎‎

Cost-effective Electro-Thermal Energy Storage to balance small scale renewable energy systems

To decarbonise the energy production system, the share of renewable energy must increase. Particularly for small-scale stand-alone renewable energy systems, energy storage has become essential in providing electricity when the demand is high, for example, during the night. Although there are many different storage technologies, only a few are suitable for small-scale stand-alone renewable systems. Those systems must be modular and scalable to be deployed according to the capacity needed. Currently, batteries are among the leading grid storage technologies, but the demand, particularly for Lithium-ion batteries, is also high because of the electrification needs of the transportation sector. Therefore, the question of material availability might become an issue in the future, as Lithium is a scarce and critical element. As an alternative, we introduce a new modular electro-thermal energy storage (ETES) technology that is suitable for various storage needs. This storage unit can utilise various thermal storage materials (thermal oil, molten salt, and sand) at high capacities and improved efficiencies. Our design consists of the embedment of Stirling engines and an electric heater into a thermally insulated storage tank. The source electricity is first converted to heat stored in the storage tank and then converted back to electricity when needed. Among the thermal energy storage materials studied here, sand enabled the storage system's efficiency to reach 85% thanks to its wide range of operating temperatures. The cost is projected to be up to six times lower than that of current Lithium-ion batteries. This new electro-thermal energy storage provides a promising cost-efficient, high capacity alternative for stand-alone energy systems.