Off-grid System Research Articles

Frequency optimisation and performance analysis of photovoltaic-battery water pumping system

Photovoltaic-battery water pumping systems (PVBWPSs) can provide fresh water and irrigation in off-grid areas. Previous research has focused on direct current (DC) voltage versus frequency to control the speed of a pump. However, the use of photovoltaic (PV) modules with batteries to create a high-performance hybrid system with fixed and variable frequencies of supply power remains challenging, particularly in an off-grid water pumping system with limited power and water supplies. Based on a conventional frequency conversion mode and power balance, this work addresses fixed and variable frequencies under changing solar irradiance conditions for a PV system and a PV system combined with a battery (PVB) mode to improve energy utilisation. According to DC power balance and centrifugal pump theories, a mathematical model of the power supply frequency in the PVBWPS is presented, as well as the loss of load probability (LLP) and pumping coefficient (Cp), through which the performance metrics are obtained. The formulated models are validated through the experimental PVBWPS, which includes 2.19 kWp PV modules, a 9.6 kWh battery bank, and a 0.75 kW centrifugal pump. The experimental results show that the root mean square error (RMSE) and maximum relevant error (RE) of the frequency are 0.14 Hz and 0.74 %, respectively. Consequently, the output performances are revealed via software simulation. The calculated results indicate that the maximum pumping volume for fixed-power-frequency operation is 48 Hz, which is 27.56 m3 on a sunny day and 17.63 m3 on a cloudy day. On a rainy day, the maximum pumping volume is 3.27 m3 at 41 Hz. Similarly, the Cp values reach maxima of 2.51 m3/kWh and 2.11 m3/kWh at 48 Hz in both sunny weather and cloudy weather, respectively, while on rainy days, the Cp peaks at 0.77 m3/kWh at 41 Hz. Moreover, every 1 Hz increase in the fixed frequency mode leads to a rise in the LLP, while the minimum change is at 46–48 Hz for cloudy and rainy days. Furthermore, the simulations revealed that for variable frequency control, the volume of water pumped in the PVB mode reached 40.19 m3, 29.36 m3, and 15.11 m3, which are increased by 4.91 %, 21.83 % and 103.09 % compared with the variable frequency PV mode, and 45.83 %, 66.53 % and 362.08 % higher than in PV fixed frequency mode, respectively. Compared with the PV mode, the system weighted efficiency of the variable-frequency PVB mode is increased by 2.06 %, 4.98 %, and 8.36 % under three weather conditions. This work provides critical theoretical guidelines for the design and operation of high-performance PVBWPs.

Oxygen excess ratio feedforward control based on ESO for PEMFC in DC off-grid hydrogen production systems

Oxygen excess ratio (OER), which is influenced by the air flow input to the cathode, is one of the important factors affecting the performance of fuel cell system. Insufficient oxygen supply will result in a sharp drop in output voltage, while an excessive supply will bring about a large parasitic power load on the air compressor, reducing the net output power of the system and operating efficiency. Both insufficient and excess oxygen supply can adversely affect the operating life of the proton exchange membrane fuel cell (PEMFC). Due to the serious nonlinear, hysteresis, uncertainty and interference in the process of OER control, this paper proposes an OER feedforward control based on extended state observer (ESO) for a PEMFC auxiliary system with the ESO to predict the total disturbance to improve the dynamic response of the system with large time delay utilizing terminal sliding mode control (TSMC). The control strategy is divided into two stages. The first stage constructs an ESO to realize real-time observation of the state variables required for the internal operation of the auxiliary machine system and the PEMFC, and yields the air compressor voltage control signal through terminal sliding mode control. In the second stage, combined with V/f control for the compressor, the transmitted air flow is adjusted, ultimately achieving the goal of changing the OER of the PEMFC and improving operating efficiency. The simulation results show that the proposed control strategy has good anti-interference capabilities, a faster response, and less overshoot. The gas flow transmission in the gas supply system is more robust, the PEMFC operation is safer, and its lifespan is extended.

Off-Grid Electric Vehicle Charging Station with Integrated Local Server OCPP Protocol as a Management System

Abstract Electric vehicles are widely regarded as pivotal in driving the sustainability of transportation networks forward, thanks to their capacity to diminish carbon emissions, enhance air quality, and bolster the robustness of electricity grids. The accessibility of charging infrastructure and the subjective norms that endorse electric mobility actively shape the electric vehicles acceptance. In this study, Our main goal is to provide off-grid electric vehicle charging infrastructures and the data communication protocols that connect to servers. We analyze the specifications of the OCPP (Open Charge Point Protocol) with an emphasis on its applicabillity for electric charging stations for vehicles. Our research concludes that off-grid electric vehicle charging systems can be effectively applied to small electric vehicles such as electric motorcycles, scooters, and bicycles. The OCPP data communication protocol can also support interactions between small electric vehicle charging stations and central server management systems (CSMS). Furthermore, we tested the electric vehicle charging process for a duration of two hours, and the charging station consistently produced stable voltage, current, and power output, matching the inverter outputs and fulfilling the specifications required by electric vehicle charging adapters. Analysis of throughput data indicates a positive correlation between the number of operational ports at a charging station and the volume of data processed by the server. However, beyond a certain threshold a decline in data transactions was observed, attributable to data loss.

The Long-Term Usage of an Off-Grid Photovoltaic System with a Lithium-Ion Battery-Based Energy Storage System on High Mountains: A Case Study in Paiyun Lodge on Mt. Jade in Taiwan

The Long-Term Usage of an Off-Grid Photovoltaic System with a Lithium-Ion Battery-Based Energy Storage System on High Mountains: A Case Study in Paiyun Lodge on Mt. Jade in Taiwan

An Analysis of Hybrid Renewable Energy-Based Hydrogen Production and Power Supply for Off-Grid Systems

Utilizing renewable energy sources to produce hydrogen is essential for promoting cleaner production and improving power utilization, especially considering the growing use of fossil fuels and their impact on the environment. Selecting the most efficient method for distributing power and capacity is a critical issue when developing hybrid systems from scratch. The main objective of this study is to determine how a backup system affects the performance of a microgrid system. The study focuses on power and hydrogen production using renewable energy resources, particularly solar and wind. Based on photovoltaics (PVs), wind turbines (WTs), and their combinations, including battery storage systems (BSSs) and hydrogen technologies, two renewable energy systems were examined. The proposed location for this study is the northwestern coast of Saudi Arabia (KSA). To simulate the optimal size of system components and determine their cost-effective configuration, the study utilized the Hybrid Optimization Model for Multiple Energy Resources (HOMER) software (Version 3.16.2). The results showed that, when considering the minimum cost of energy (COE), the integration of WTs, PVs, a battery bank, an electrolyzer, and a hydrogen tank brought the cost of energy to almost 0.60 USD/kWh in the system A. However, without a battery bank, the COE increased to 0.72 USD/kWh in the same location because of the capital cost of system components. In addition, the results showed that the operational life of the fuel cell decreased significantly in system B due to the high hours of operation, which will add additional costs. These results imply that long-term energy storage in off-grid energy systems can be economically benefited by using hydrogen with a backup system.

Techno-economic analysis and dynamic power simulation of a hybrid solar-wind-battery system for power supply in rural areas in Pakistan

This study presents the optimal design and operation of a proposed hybrid renewable energy system (HRES) for the electrification of a residential building in rural areas in Pakistan. The main contributions of this study are twofold. Firstly, it develops a size optimization model based on the particle swarm optimization (PSO) technique to determine the optimal configuration for two hybrid renewable energy systems (HRES), including both grid-tied and off-grid modes, integrating wind and photovoltaic (PV) systems with battery storage. The optimal configuration is determined by minimizing the levelized cost of electricity, using local meteorological and electricity load data, along with technical specifications of the main HRES components. Secondly, dynamic simulations of two HRES configurations are conducted, using MATLAB Simulink, ensuring the optimal energy balance between multiple energy sources and the load at each operation hour. To meet an annual electrical demand of 131.035 MWh, the grid-tied HRES yields 146.081 MWh annually, with solar contributing 68.85 MWh and wind 77.272 MWh. Conversely, the off-grid system generates 133.533 MWh annually, with solar and wind output power at 43.932 MWh and 89.601 MWh, respectively. The grid-tied system achieves an LCOE of approximately 0.29 $/kWh, with optimal wind turbine and PV capacities of 11 kW and 29 kW, respectively. While in off-grid configuration, the off-grid scenario exhibits an LCOE of 0.91 $/kWh, with optimal capacities of 10 kW for wind turbine, 20 kW for PV, and 2437.5 AH for batteries. The findings provide insights relevant to diverse locations, emphasizing the importance of local meteorological and geographical data. Multiple case studies ensure the robustness and applicability of the proposed system under varying conditions.

Feasibility of Photovoltaic-Powered Hydrogen Production for Off-Site Refueling Stations in Iraqi Cities: A Techno-Economic Analysis

The study explores the feasibility of using a photovoltaic (PV) energy system to produce hydrogen for off-site hydrogen refueling stations (HRS) in three Iraqi cities (Karbala, Maysan, and Nineveh), focusing on a comprehensive system model consisting of a 558 MWp off-grid photovoltaic system, a 157.5 MWp proton exchange membrane (PEM) electrolyzer, a converter, and a hydrogen storage tank. Utilizing HOMER Pro software for system simulation and MATLAB, with consedaring 28 years from 2022 to 2050 life span, incorporating hourly weather data for 2022 to optimize system performance. The outcomes identify that the Karbala city as the most cost-effective for green hydrogen production, highlighting the economic benefits of PV technology, which presents the most economical option with a levelized energy cost of $5,010/GWh. The project is projected to produce 10.61 million kg of hydrogen annually at a production cost of $2.75/kg, with an overall project cost estimated at $372.77 million. The results are of strategic significance for Iraq transportation sector, supporting the development of a robust green hydrogen infrastructure for HRS. This infrastructure is expected to promote sustainable transportation practices and reduce reliance on fossil fuels, contributing significantly to the energy transition in Iraq. This techno-economic analysis provides a foundational assessment for stakeholders considering investments in renewable hydrogen production and infrastructure development.

Determination of Solar Irradiance Benchmarks for Municipal Off-grid Photovoltaic Power System Development in Lagos State, Nigeria

The paper examined the solar irradiance benchmarks for off-grid photovoltaic power systems development in Ikeja, Lagos State, Nigeria as a power supply alleviation strategy in the State and strategic model for other sponsors in Lagos State and Nigeria. Solar irradiance analysis, an energy technology foresight analysis method for effective energy planning and evaluation, was used. The solar irradiance analysis determined three solar irradiance measurements – the NiMet pyranometer, the NASA satellite, and the Mechlouch and Brahim (2008) model. The study determined the model graph to be incongruous with the NiMet pyranometer and NASA satellite-derived graph plots while the NIMet and NASA satellite plots essentially overlapped. The study adjudged the model graph as being theoretical and inappropriate while the NiMet and NASA readings gave realistic plots which were deemed acceptable as suitable solar irradiation benchmarks. In conclusion the study established solar irradiance benchmarks of 15 MJ/m2/day (upper (maximin) value) and 20 MJ/m2/day (lower (minimax) value) for the photovoltaic power systems development in Ikeja, Lagos State, Nigeria.

Optimization method for capacity configuration and power allocation of electrolyzer array in off-grid integrated energy system

Hydrogen production using renewable energy is in line with China's the goal of carbon peak and carbon neutrality. The construction of off-grid hydrogen energy industrial park can effectively achieve local utilization of renewable energy and develop the green hydrogen industry. However, off-grid hydrogen energy industrial park has not the compensation and sustentation from large power grid, the stable operation and economic production of electrolyzer are affected by significant factors, such as power fluctuation and frequent start stop. Therefore, this paper proposed the optimization method for capacity configuration and power allocation of electrolyzer array in off-grid integrated energy system. Firstly, based on units of energy supply, energy conversion, and energy storage, a structural model of off-grid integrated energy system was established. Then, by analyzing the operational characteristics of single electrolyzer and electrolyzer array, flexible mode of multiple electrolyzers operating in combination was proposed. Furthermore, considering the hydrogen production cost, the mean of hydrogen production volatility and penalty cost, the capacity configuration and power allocation methods for electrolyzer array were proposed, and the optimization problem is solved with multi-objective particle swarm optimization algorithm. Finally, the hydrogen energy industrial park in Zhangye is taken as example to verify the effectiveness of above research content. Compared to a single type of alkaline electrolyzer, the mean of hydrogen production volatility of multiple electrolyzers operating in combination has decreased by 43.2 %, the hydrogen production quantity has increased by 9.74 %. Compared to a single type of proton exchange membrane electrolyzer, the hydrogen production cost has been reduced by 14.16 %. Compared with the balanced running mode, the flexible operation mode can improve the cost-effective and quantity of hydrogen production.

The Significance of Cable and Nonlinear Loads to Losses, Voltage Drop, and Harmonics in Remote Off-Grid Systems

The Significance of Cable and Nonlinear Loads to Losses, Voltage Drop, and Harmonics in Remote Off-Grid Systems

Master slave game-based optimization of an off-grid combined cooling and power system coupled with solar thermal and photovoltaics considering carbon cost allocation

Analogously to power trading models used by electricity companies, the implementation of an energy retailer can address the trading challenges experienced by end-users with decentralized energy consumption patterns. This research develops an off-grid solar-gas energy system to fulfill the cooling and power needs of buildings. Upon creating thermodynamic models, an innovative energy trading mechanism is introduced through an energy retailer, followed by the application of a master-slave optimization method aimed at maximizing participants' profits while incorporating carbon trading and demand response strategies. Through a case study and comparison of four different scenarios, the findings demonstrate that integrating solar thermal and electrical systems leads to the highest profitability, with the energy system's revenues remaining below 10%. The study determines the maximum selling prices for cooling and electricity as 0.231 $/kWh and 0.232 $/kWh, respectively, and highlights that varying carbon allocation rates have minimal effects on user profits. This work sheds light on the sustainable progression of distributed energy systems and presents motivating implications for a diverse audience interested in such advancements.

Elucidating Stakeholder Prioritization for Sustainable Off-Grid Renewable Electrification using the Fuzzy AHP-GPESTLE Framework: A Comprehensive Analysis

Poverty has been linked to the reality of the world’s developing countries, especially in far-flung rural areas where the lack of energy access plays a significant role in the misery of the poor and disadvantaged people. To achieve universal access to energy, the role of rural electrification was emphasized, and off-grid small-scale electricity generation from renewable sources was expected to be a promising solution. However, in the Philippines, where off-grid island communities are scattered along its archipelago, the deployment of such systems in rural areas is still a challenge among stakeholders due to the consideration of various conflicting factors that may put the potential economic gains and other social and environmental benefits at risk. To better understand the multifaceted nature of off-grid energy system sustainability through the perspective of its stakeholders, the Fuzzy Analytical Hierarchy Process (FAHP) was used to determine their most prioritized factors in determining the viability and sustainability of such systems following the GPESTLE framework. This provides a comprehensive and more relevant approach to performing sustainability analysis by looking into the geographical (G), political (P), economic (E), social (S), technological (T), legal (L), and environmental (E) dimensions of these assemblies. The prioritization of 74 expert stakeholders, coming from the industry, academy, and government institutions, has been elucidated by having them perform pairwise comparisons among the various GPESTLE criteria through a survey. Using FAHP, prioritization or weights were already generated per G-PESTLE criterion and sub-criterion. It was found out that among the three institutions, the industry players have the lowest environmental prioritization and can be increased by developing them with cost-efficient renewable technologies. The availability of technology manufacturers and transportation accessibility has been the main consideration in ensuring the reliability of the system’s operation. Minimizing LCOE and increasing the people’s capacity to pay should also be a priority to secure the project’s financial viability. The presence of a community comprehensive land use plan has also been highly favored among developers, which can allow faster processing of permits on the use of indigenous resources and agricultural lands. With these findings, this framework aims to guide policymakers to properly address the challenges of islands lying low in prioritization due to problems on certain sustainability factors. These insights can be relevant in the drafting of a transitional framework on the renewable electrification of off-grid islands, which were usually left out or minimally given attention in the national electrification plans of governments.Poverty has been linked to the reality of the world’s developing countries, especially in far-flung rural areas where the lack of energy access plays a significant role in the misery of the poor and disadvantaged people. To achieve universal access to energy, the role of rural electrification was emphasized, and off-grid small-scale electricity generation from renewable sources was expected to be a promising solution. However, in the Philippines, where off-grid island communities are scattered along its archipelago, the deployment of such systems in rural areas is still a challenge among stakeholders due to the consideration of various conflicting factors that may put the potential economic gains and other social and environmental benefits at risk. To better understand the multifaceted nature of off-grid energy system sustainability through the perspective of its stakeholders, the Fuzzy Analytical Hierarchy Process (FAHP) was used to determine their most prioritized factors in determining the viability and sustainability of such systems following the GPESTLE framework. This provides a comprehensive and more relevant approach to performing sustainability analysis by looking into the geographical (G), political (P), economic (E), social (S), technological (T), legal (L), and environmental (E) dimensions of these assemblies. The prioritization of 74 expert stakeholders, coming from the industry, academy, and government institutions, has been elucidated by having them perform pairwise comparisons among the various GPESTLE criteria through a survey. Using FAHP, prioritization or weights were already generated per G-PESTLE criterion and sub-criterion. It was found out that among the three institutions, the industry players have the lowest environmental prioritization and can be increased by developing them with cost-efficient renewable technologies. The availability of technology manufacturers and transportation accessibility has been the main consideration in ensuring the reliability of the system’s operation. Minimizing LCOE and increasing the people’s capacity to pay should also be a priority to secure the project’s financial viability. The presence of a community comprehensive land use plan has also been highly favored among developers, which can allow faster processing of permits on the use of indigenous resources and agricultural lands. With these findings, this framework aims to guide policymakers to properly address the challenges of islands lying low in prioritization due to problems on certain sustainability factors. These insights can be relevant in the drafting of a transitional framework on the renewable electrification of off-grid islands, which were usually left out or minimally given attention in the national electrification plans of governments.

Effect of Renewable Energy Consumption on Economic Growth in Kenya

One of the significant economic growth problems in Kenya is the income inequality and poverty rate which has made it impossible for among the households to afford clean energy. While the country has experienced some economic growth over the years, it is not yet clear whether the adoption of renewable energy has been the cause of this growth. There have been mixed results on the studies done on renewable energy use and their effect on economic growth and therefore calls for further research. The general objective of the study was to determine the effect of renewable energy consumption on economic growth in the Kenyan economy. Specifically, the study specific objectives were to determine the effect of solar energy consumption, geothermal energy consumption, and hydroelectric energy consumption and wind power energy consumption on economic growth in Kenya. This was made possible through an analysis of 37 years’ data from 1986 to 2022 on an annual time series basis. This study employed the endogenous growth theory as the main theory of the study and triple bottom line theory as the supplementary theory. The study employed an explanatory research design and analyzed data using the Autoregressive Distributed Lag model to establish whether renewable energy consumption had any effect on economic growth of the Kenyan economy. Findings of diagnostic test demonstrated that there was no multicollinearity among the independent variables, residuals were homoscedastic, and there was no autocorrelation among the residuals. The results of the Jarque bera normality test showed that the study's variables were normally distributed. The Augmented dickey fuller unit root test both showed that there was no unit root and that the variables had a short run relationship. Additionally, the model's stability over time was confirmed by the CUSUM test. Findings of the study were: the relationship between hydroelectric energy consumption and economic growth was positive and significant, wind power energy consumption and economic growth was positive and significant and between geo-thermal energy consumption and economic growth was positive and significant. The study concluded that geo-thermal energy consumption, hydroelectric energy consumption and wind power energy consumption significantly affect economic growth positively. The study therefore recommends that the Kenyan government should set ambitious targets for renewable energy consumption such as a specific percentage of electricity generation or overall energy consumption. The Kenyan government should enhance and enforce regulatory frameworks specific to renewable energy in order to provide a stable and predictable investment environment. Finally, the Kenyan government should focus on expanding access to renewable energy solutions in rural areas, where energy access is limited. Implementing off-grid renewable energy systems, such as solar home systems and mini-grids, can provide clean and reliable electricity to rural communities.

The role of storage in energy security performance based on diversification and concentration for distributed energy systems

This work addresses the use of diversification and deconcentration strategies of primary sources of energy supply for the multi-objective design of distributed generation systems based on renewable sources. The Shannon–Wiener and Herfindahl–Hirschman indices are proposed as optimal design objectives. The utopia-tracking method is used to identify trade-offs between the total annual cost of the system and the efficiency of the storage system. The storage system is included in the assessment of diversification and deconcentration due to its functions as a backup unit in the event of adverse system operating conditions. Cases of interconnected and off-grid systems are addressed. The results show that, by including the storage system, an over-diversification of supply sources is generated and that, in the absence of various sources, as occurs in off-grid systems, storage generates sufficient flexibility to reach a trade-off among economic performance, diversification of supply sources and energy efficiency. The robust nonlinear programming model is fed with real data from a residential building.

Off-Grid Power Management System using IoT

The "Off-Grid Solar Power Management System Using IoT" project is a solution to address the energy needs of remote and off-grid locations through the integration of renewable solar power and Internet of Things (IoT) technology. In the face of limited access to conventional power sources, this project leverages IoT devices and smart technologies to create a robust energy management system. The system allows for the efficient capture, storage, and distribution of solar energy while enabling real-time monitoring. Key features include data collection on solar panel performance, energy consumption, and user-friendly interfaces accessible through web applications. This project demonstrates the potential to provide sustainable, reliable, and environmentally friendly energy solutions for off grid communities here in Malawi, enhancing their quality of life and contributing to global efforts for clean energy adoption

Integration of very small modular reactors and renewable energy resources in the microgrid

Hybrid microgrids, integrating local energy resources, present a promising but challenging solution, especially in areas with limited or no access to the national grid. Reliable operation of off-grid energy systems necessitates sustainable energy sources, given the intermittent nature of renewables. While fossil fuel diesel generators mitigate risks, they increase carbon emissions. This study assesses the viability of integrating a very small modular renewable energy reactor into a microgrid for replacing conventional diesel generators, substantially curbing greenhouse gas emissions. A comprehensive analysis, including design and economic evaluation, was conducted for an off-grid community microgrid with an annual generation and load of 8.5 GWh and 7.8 GWh, respectively. The proposed microgrid configurations incorporate very small modular reactors, alongside solar, wind, and battery storage systems. MATLAB modeling and simulation across eight cases, accounting for seasonal variations, demonstrate the technical and economic feasibility of case 7. This configuration, integrating modular reactors, photovoltaics, wind turbines, and battery storage, satisfactorily meets load demands. Notably, it boasts a high internal rate of return up to ∼31% and a shorter payback period of around 4 years compared to alternative scenarios.

Optimal sizing of off-grid microgrid building-integrated-photovoltaic system with battery for a net zero energy residential building in different climates of Morocco

An optimal sizing of an off-grid microgrid system composed of photovoltaic (PV)/building integrated photovoltaic (BIPV)/battery energy storage installation is undergone for Net Zero Energy Residential Building blocks across six different climates of Morocco. The Particle Swarm Optimization algorithm is used to find the optimal sizing of the system, by considering the hourly spatiotemporal variations in both solar energy availability and energy demand, with the lowest Total Annualized Cost as the objective function and capacities of BIPV and battery as decision variables. The methodology adopted focuses on main load fulfillment through direct PV and BIPV power supply, backed by battery energy storage technology, to continually guarantee self-sufficiency. A key metric, the load cover factor, is introduced to quantify the ratio by which the load demand is satisfied by the solar PV and BIPV systems. The findings show that the optimal sizing of the BIPV system can help to improve the load cover factor by 0.68–2.58 %. Moreover, integrating BIPV system with PV system and Battery leads to a reduction in the Levelized Cost of Energy with approximately 8.7–20.72 %, as opposed to utilizing only the PV system and battery. Depending on the local climate, the levelized cost of energy ranges from $0.366/kWh in Ouarzazate city up to $0.664/kWh in Ifrane city. Lastly, this holistic approach aims to transform the building from its traditional role as an energy consumer to a carbon-free energy prosumer.

Design, modeling, and simulation of a PV/diesel/battery hybrid energy system for an off-grid hospital in Ethiopia

In the pursuit of sustainable energy solutions, off-grid hybrid systems have emerged as a promising avenue, catering to the electrification needs of rural areas. These systems encompass a multifaceted approach, addressing concerns of reliability, sustainability, and environmental preservation. Leveraging advanced tools such as HOMER modeling, the design and simulation of hybrid off-grid systems, alongside the evaluation of existing diesel generator (DG) power supply, have become imperative. This paper embarks on a comprehensive exploration with the overarching objective of designing, modeling, and simulating an off-grid power system tailored for the Shinshicho Primary Hospital. Nestled in the heart of Shinshicho Town within the Kembata Tembaro Zone of Ethiopia, this healthcare facility stands as a focal point for community well-being. The proposed hybrid system integrates solar PV, diesel generators, and battery storage, offering a robust and resilient energy solution. Throughout the optimization process, a primary load demand of 276 kgwatt-hours per day and a peak load of 40 kW were pivotal considerations. The financial cost of this hybrid system results in an initial capital requirement of $160,500, complemented by operational and maintenance costs amounting to $14,824. Over the projected 20-year lifespan, the total net present cost (NPC) is estimated at $216,155. With these economic parameters in mind, the cost-effectiveness of the selected hybrid system is underscored by a cost of energy (CEO) of 0.187 dollars per kilowatt-hour. This metric not only highlights the economic viability of the proposed solution but also positions it as a sustainable and financially prudent choice for meeting the energy needs of Shinshicho Primary Hospital.

Carbon pricing and system reliability impacts on pathways to universal electricity access in Africa.

Off-grid photovoltaic systems have been proposed as a panacea for economies with poor electricity access, offering a lower-cost "leapfrog" over grid infrastructure used in higher-income economies. Previous research examining pathways to electricity access may understate the role of off-grid photovoltaics as it has not considered reliability and carbon pricing impacts. We perform high-resolution geospatial analysis on universal household electricity access in Sub-Saharan Africa that includes these aspects via least-cost pathways at different electricity demand levels. Under our "Tier 3" demand reference scenario, 24% of our study's 470 million people obtaining electricity access by 2030 do so via off-grid photovoltaics. Including a unit cost for unmet demand of 0.50 US dollars ($)/kWh, to penalise poor system reliability increases this share to 41%. Applying a carbon price (around $80/tonne CO2-eq) increases it to 38%. Our results indicate considerable diversity in the level of policy intervention needed between countries and suggest several regions where lower levels of policy intervention may be effective.

An off-grid solar district energy system with borehole thermal energy storage: Life cycle assessment in a subarctic region

Nunavik, a remote subarctic region covering the northern third of Quebec, Canada, relies heavily on diesel to meet residential heating demand. Solar district heating (SDH) with borehole thermal energy storage (BTES) has been developed there as one of the most promising solutions that can break the dependence on fossil fuels and develop renewable energy resources locally. Developing an SDH-BTES in Nunavik is not only a technical and economic consideration, but also an environmental deliberation. Therefore, in this study, a cradle-to-grave life cycle assessment (LCA) of both SDH-BTES and conventional systems are performed for this area. The SDH-BTES system is defined as a heating system for a community comprising 1500 m2 gross solar area and 150 borehole heat exchangers with a depth of 30 m which is modeled to analyze its environmental performance. The results are presented comparatively with the conventional heating system consisting of local household diesel furnaces. Fifteen various impact categories are introduced for the comparison and contribution of main components (solar subsystem, auxiliary subsystem, transportation, and disposal) are analyzed individually. The present analyses show that SDH-BTES performs better than local diesel furnaces regarding human health, climate change, and resources. However, ecosystem quality impact of SDH-BTES system is slightly higher than the conventional domestic diesel furnaces due to the large land occupation of underground thermal heat storage and drilling process. The SDH-BTES system can improve environmental impact by 21 % compared to the conventional system and reduces CO2 emission by 22.4 %.