Browse
Recent Submissions
Item Open Access Wind measurements using SODAR: Hirundo wind farms case study(National University of Lesotho, 2024) Rakuoane, Molibeli; Mpholo, MoeketsiThis study compares the wind data of the European Centre for Medium-Range Weather Forecasts Reanalysis Version 5 (ERA 5) to that obtained from the sound detection and ranging (SODAR) at the Rothe Plateau. It utilizes industry-standard software, Wind Atlas Analysis and Application Program (WAsP), to undertake the analysis. WAsP was employed to generate wind resource maps, to model the wind flow over complex topography and to forecast the yearly wind conditions. The availability of SODAR data, obtained from 23 January 2024, to 31 July 2024, after eliminating inaccurate and suspicious data, was 57.36%. It is commonly perceived as being of inferior quality due to its failure to meet the 90% threshold. The precision of wind resource validation is determined by the degree of accuracy and availability of the relevant data. The findings of this study show that the forecast errors of ERA 5 represent about 12.2% of the range of SODAR wind speed data, indicating a moderate level of accuracy. The normalized root mean square error (NRMSE) for wind speed and direction were found to be 0.122 and 0.359, respectively. The ERA 5 provided inaccurate wind direction. Furthermore, the mean bias error (MBE) of -1.51 m/s and -7.840, respectively, for wind speed and direction were discovered, indicating an under prediction by the ERA 5 model. The correlation coefficient (R) between the two datasets was determined to be 0.725 (72.5%). Demonstrating a robust and reliable connection between SODAR and ERA 5. However, the wind direction correlation indicated a relatively poor connection of 27.7%. With a determination coefficient (R2) of 0.525, ERA 5 is not able to capture and represent the complexity and dynamics influencing fluctuations in wind speed variations. The chosen turbine generator for the Hirundo Energy wind farm is the Vestas V162-6.0 MW, with a maximum rated power of 6.0 MW. The wind farm contributes significantly to the generation of renewable energy, with an anticipated net annual production of 75.5 GWh, about 8.9% compared to the country’s consumption of 848 GWh per annum in 2022. This proves that wind energy technology can be effectively harnessed in Lesotho and highlights the significance of data validation and farm planning for optimizing energy output and efficiency. However, due to the lack of continuous onsite measurements, the capacity factor was found to be 17.95%, compared to a global average of 30% for grid-connected wind farms.Item Open Access Tracking SDG 7 progress for Lesotho using energy indicators for sustainable development(National University of Lesotho, 2021) Kolobe, Mamontsi; Thamae, Leboli ZakEnergy is regarded as a global variable in achieving sustainable development goals (SDGs). In Lesotho however, there are no traces of how far Lesotho’s progress is regarding affordable and clean energy access status towards achieving the set SDG7 targets. There has never been any initiatives engaged for tracking the progress ever since the SDG7 targets were set globally. It is essential to know the country’s current energy status, economic stability, what needs to be improved and at what pace should the improvement be done. This study therefore traces progress of Lesotho energy sector on the four targets of SDG7: energy access (electricity and technologies for clean cooking), renewable energy and energy efficiency. The study further monitors the overall progress of the energy system towards sustainable development and indicates progress with the latest available data up to 2019 against a baseline year of 2014. The five-year data from 2014 to 2019 is going to be projected from 2020 until 2030 to examine the possible progress that would be achieved through two scenarios; Business as Usual (BAU) and Sustainable Development (SD) scenario. It is with SD scenario that certain policies will be informed which will help accelerate the progress. The results from this study suggest that only 68.4% of population will have electricity access by 2030 under BAU scenario. This verifies the SDG gap of 31.6% to meet 100% access target. Moreover only 50% of population will have clean cooking access by 2030 leaving a gap of another 50% to have 100% access. On the other hand, by 2030 renewable energy share will only be 45.5% and still lacking 18.5% to double the renewable energy share of 2014 to 64%. Results further show that in 2030, the energy efficiency improvement will only be 14.3 MJ and still lacking 5.3 MJ to double the improvement to 19.6 MJ. In essence, all four SDG7 targets are not going to be achieved by 2030; hence more powerful policies are needed to make these targets a success.Item Open Access Tracing energy democracy in decentralized mini-grid projects in Lesotho(National University of Lesotho, 2024) Tsotleho, Paki; Tsoeu-Ntokoane, SeroalaAs the Lesotho electricity generation landscape transitions from centralized modes of systems towards decentralized generation and distribution systems, there exists a potential challenge of elite capture in governance structures and frameworks that may overlook the social dimensions that guarantee the sustainability of such systems. This study interrogates the Lesotho decentralized mini-grid energy systems landscape for traces of the energy democracy agenda as a globally sought-after discourse due to its nature to either be a deterrent or a stepping stone for sustainable energy development using an abductive research method. This discourse is especially important for knowledge production that can potentially inform national policy associated with the transition from productive use of energy to sustainable use of energy. The report starts by scrutinizing the available written work on mini-grids as a whole, legal or otherwise, establishing the broad national perspective of the development of the mini-grids in Lesotho. This is then complemented by assessing existing case studies of Ha Makebe and Motete in rural Lesotho to primarily focus on the role that decentralization plays in elements of energy democracy in mini-grids developments. The research takes on a life-cycle approach as the main analytical framework, under which institutional processes and practices are matched across the four identified phases of the project life-cycle. This is further supported by evaluating the host communities on their status as energy citizens under the energy democracy agenda. The results of this research study demonstrate the status of the policy and legal framework to imply the energy democracy agenda rather than it is inferred. This observed state of policy and legal framework further spills into the formulation approaches on standard governance practices that focus on infrastructure optimization as opposed to project sustainability which speaks to the effectiveness of the institution to govern such developments. Lastly, the results of this study present the host beneficiaries as eager and willing citizens to exercise their collective role as energy citizens to institutionally hold other stakeholders accountable under the energy democracy agenda concerning the development of decentralized mini-grids in Lesotho as to achieve a just and equitable energy transition.Item Open Access The potential impact of climate change on wind spped and solar radiation in Lesotho(National University of Lesotho, 2024) Tsolele, Taelo; Mpholo, MoeketsiIn this study, a Jupyter Notebook software was utilized to study the potential impact of climate change on wind speed and solar radiation in Lesotho using a CORDEX-Africa regional climate model to simulate the past, present, and future climate conditions under different scenarios at 10 m above ground level. Historical climate data from 1950 to 2005 showed a consistent average wind speed of 1.50 - 3.0 m/s and solar radiation of 200 - 225 W/m2, except in the north-east of the country where the Butha-Buthe and Mokhotlong districts are located, solar radiation of 175 - 200 W/m2 was averaged. The RCP4.5 scenario projected a stable average wind speed ranging from 1.50 - 2.75 m/s except for the peak of 3.00 m/s in 2030. The projected solar radiation had a minimum average solar radiation of 150 W/m2 and a maximum average solar radiation of 275 W/m2, reaching up to 340 W/m2 by 2045. The RCP8.5 scenario projected a similar wind speed trend, exceeding 3.00 m/s from 2042 to 2045, and a peak solar radiation of 370 W/m² in 2043. These projections imply that Lesotho's solar and wind energy generation will not be negatively impacted, thus offering significant opportunities for sustainable energy development. The findings support investments in wind and solar infrastructure throughout the country, extending to places such as Butha Buthe, Quthing, and Mokhotlong with the newly acquired renewable energy resources due to climate change.Item Open Access The impact of intermittent renewable energy generators on Lesotho National Electricity Grid(National University of Lesotho, 2020) Mokeke, Sebota; Thamae, RLesotho is confronted with huge challenge of low electricity access, with 63.9 % of the population lacking access to electricity. Lack of electricity impedes both economic and social development. However, Lesotho has abundant renewable energy resources that can be exploited through large integration of renewable energy sources. The inherent variability and uncertainty of renewable energy sources (solar-PV and wind) creates both operational and planning challenges for the power system. This results in the reluctance of the power system operators integrating largescale renewables to the national grid due to the power system stability problems. The characteristics of the intermittent renewable energy generators mandates that careful grid impact studies be performed in ensuring that the power grid is operated stably. The thesis focuses on the impact of the Intermittent Renewable Energy Generators (IREGs) on the power stability of Lesotho electrical grid considering both solar photovoltaic (PV) and wind generation at Ha-Ramarothole and Letseng respectively. The integration of IREGs involves both steady state and dynamic analysis of the electrical network. To this aim, the thesis assesses the impact of the IREGs on the stability of Lesotho electrical network at transmission level. In addition, maximum allowable penetration levels were determined at the point of interconnection. Load flow simulations were performed to assess the steady state performance of the electrical network. Furthermore, the transient analysis was performed by applying the 3-phase short circuit at the critical points of the network and observing how voltage, frequency and rotor angle stability were affected and evaluated against grid code of Lesotho. The simulations were performed using DigSILENT PowerFactory software, which was used to model the electrical network of Lesotho. The maximum allowable penetrations for solar was about 19 % at substation at Ramarothole while for the wind it was found to be 27 % at Letseng substation. The simulations revealed that increased penetration of the IREGs led to grid instability. For all the simulations, frequency stability was observed except for the penetration of 36 MW for solar farm. The voltage violations at the Tlokoeng substation of 1.051 p.u. resulted from penetration limit of 52 MW capacity of the wind farm at Letseng. The solar penetration limit resulted from the rotor angle instability as increased penetration resulted in large rotor angle oscillations.Item Open Access The genderperspective of socio-economic determinants of household cooking energy consumption in Lesotho(National University of Lesotho, 2023) Nkaile, Palesa; Mpholo, Moeketsi; Thamae, RetselisitsoeUnveiling gender dynamics in household energy consumption is a pathway to empowerment and sustainable development since the inaccessibility of electricity perpetuates gender inequality due to women’s higher involvement in time-consuming and unproductive activities such as wood collection and cooking. This study investigates the variations in fuel consumption shares between female-headed and male-headed households and explores the determinants of these differences from a gender perspective. Using the Tobit regression model to analyse the 2017 Household Energy Consumption Survey (HECS) data, the study establishes the statistical significance of socioeconomic variables on household shares of biomass, paraffin, LPG, and electricity, assuming that the shares are left-censored. The findings reveal intriguing patterns, such as the increasing shares of dirty fuels with the age of the household head regardless of gender. However, education impacts female and male-headed households differently, with female-headed households generally increasing their share of high-end fuels while male-headed households opt for transition fuels. Increasing income and households in peri-urban and urban areas are also not discriminatory in terms of gender as both reduce the share of dirty fuels and rely more on cleaner alternatives. Conversely, increasing household size affects female-headed but not male-headed households as they are found to increase the shares of transition fuels in summer but reduce the share of cleaner fuels in winter. Therefore, the study emphasises the need for targeted education and economic empowerment programmes, awareness campaigns, and income-generating skills development policy interventions to foster clean energy access and improve the well-being of Basotho households.Item Open Access Techno-economic analysis and policy design for PV electricity net-metering systems in Lesotho(National University of Lesotho, 2025) Moleko, Lebohang AlbertLesotho imported 65% of its electricity from Electricidade de Moçambique (EDM) and Electricity Supply Commission (ESKOM) in 2019/2020 (Lesotho Electricity Company (LEC), 2020). This is higher as compared to 59% in 2018/2019 ( Lesotho Electricity and Water Authority (LEWA), 2019). This shows that there is an increasing demand, but stagnant generation capacity hence the need for the security for the supply of electricity in Lesotho. Studies have shown that the interconnection of Solar Photovoltaic (PV) systems to the grid can reduce electricity imports amongst others. The objective of my study is to design optimum grid-connected solar PV systems for residential, commercial, industrial and institutional purposes; predict the system field performance and d o a cost-benefit analysis on net metering. Optimal PV system is designed using the Typical Meteorological Year data closest to Maseru. PV power and inverter power outputs are calculated for each hour of the given typical year. The different load profiles from the utility are also used. Net metering policy options guidelines are designed such that PV electricity is sold to the grid at the utility retail price with no PV capacity cap for net metered systems. The benefits from net metered PV systems are calculated. These are from surplus sales, avoided energy savings and peak shaving in the billing period of 12 months. The results show that with the current electricity tariffs, the PV system that gives the net electricity payments of zero at the end of the billing period for commercial and industrial customers results in negative NPV values which indicate that the system is not acceptable. On the contrary, the net-metered residential PV system offers the profitability index of 2.7643 at the discount rate of three percent (3%) which is very attractive for investment on the customer‟s perspective. The internal rate of return of the project is thirteen percent (13%). Based on these results, it is concluded that with the current tariff settings for residential customers, only the residential PV net metering is technically and economically viable. As for the commercial and industrial activities, PV net metering is technologically viable but not economically viable. The changes in some variables such as dropping of solar PV systems‟ capital and the increase in energy charges to $0.0423 and $0.039 for commercial and industrial customers respectively, can make the systems acceptable. The reasonable Net Present Value (NPV) values are likely to increase the adoption rate of electricity net metering. H o w e v e r , to attract more investment into the net-metering system, the interest rate of the investment should always be greater than the inflation rate. The larger the range between the two, the more attractive the investment can be.Item Open Access Solar water purification system for rural areas(National University of Lesotho, 2025) Makebe, Rethabile; Jonathan, Enock; Kao, MorutiThis dissertation examines the design, efficacy, and viability of a hybrid solar photovoltaic-thermal (PVT) and ultraviolet (UV) water purification system specifically developed for rural Lesotho, featuring a case study in the Mohale Basin. The system incorporates thermal energy capture by the solar PVT array to preheat feedwater before reverse osmosis (RO) treatment, hence improving membrane efficiency and minimizing fouling hazards. The electricity produced by the PVT array energizes UV disinfection devices and water pumps, while battery storage guarantees continuous operation under low solar irradiance circumstances. Two optimized setups, that is, 5.2 kWp and 14.4 kWp were simulated by PVsyst, underpinned by mathematical modelling and validated against DuPont WAVE software. The 14.4 kWp configuration exhibits enhanced energy reliability with feedwater preheating to 40 °C, recovery rates of 60%, and specific energy consumption as low as 1.06 kWh/m³. Comparative evaluations solar PV and solar PVT RO demonstrate that the incorporation of PVT preheating with dual-stage RO markedly decreases operating pressures and enhances water quality. Analysis indicated that the smaller 5.2 kWp system, despite its reduced initial expenditure, yields water at a higher Levelized Cost of Water (LCOW) of USD 1.25/m³. The larger 14.4 kWp system on the other hand attained a lower LCOW of USD 0.75/m³, illustrating the benefits of economies of scale in hybrid PVT-RO configurations. This work demonstrates the viability of scalable solar-driven water purification systems for offgrid rural Lesotho, with implications for sustainable development and climate adaptation, providing a viable approach to furthering Sustainable Development Goals 6 (Clean Water and Sanitation) and 7 (Affordable and Clean Energy) in Lesotho.Item Open Access Rehabilitation of Katse Dam mini-hydropower plant(National University of Lesotho, 2022) Thamae, Ntoampe W; Makhele, Molefe; Khaba, LiphapangThe Katse Dam Mini-Hydropower station was designed to generate and supply electricity to auxiliary systems without connecting to the grid. This would increase the dam power supply and reliability thereby reducing the electricity bill incurred on the Lesotho Highland Water Project (LHWP) for operations. However, to date, the Mini-Hydropower station is not fully operational. In this study, the decommissioned Katse Dam Mini-Hydropower plant’s rehabilitation is evaluated. Three significant activities characterized this rehabilitation process. The upgrading of electro-mechanical equipment or damaged parts, using condition assessment filters. Uprating is explored by flow duration plots for the possibility of increasing plant capacity. Lastly, the capacity dispatch (Integration) is studied intensively with computer software package (DigSilent Power Factory), for grid integration alternatives. In general, electrical equipment is the plant's most vulnerable to fatigue. Mechanical equipment is moderately damaged, with governor and guide bearing systems standing out. Assessment of the potential of the plant’s capacity increase revealed that the reservoir compensation flow regime resulted in minimum design values of head and discharge being fulfilled 96% of the time. The Katse Dam load capacity is met 90% of the time, while the maximum single machine power is exceeded 84% of the time. The Mini-Hydropower stable response to dam load growth and decline without a grid was shown in the grid integration option. However, there was a substantial deviation to a sudden loss of grid without load shedding, and the local bus voltage dropped below 6% tolerance. The findings of this investigation demonstrated the need for this plant to be rehabilitated. All the necessary tests on relevant components point to the goals of the plant and the necessity for restoration. According to the economic study, implementing this project will result in a 9year return on investment and a 2.02 MWh annual energy guarantee, which is 54% of the yearly energy consumption of the auxiliary systems.Item Open Access Ramarothole solar PV plant technical performance analysis(National University of Lesotho, 2025) Sehobai, MosiliDespite the country’s persistent energy deficit and reliance on imports, access to reliable data on the technical performance of commercial solar photovoltaic (PV) plants in Lesotho remains limited. This study evaluates the performance of the 30 MWp grid-connected Ramarothole Solar PV Plant to determine its efficiency, reliability and long-term sustainability. The analysis applies International Energy Agency (IEA)-recommended performance indicators, namely Performance Ratio (PR), Capacity Factor (CF) and Final Yield (YF). Plant operational data measured at 30minute intervals from January to December 2024 was assessed. The results show that the plant generated a total of 59,326.40 MWh of electricity, achieving an annual average PR of 94.8%, CF of 21%, and YF of 1884.3 hours. These values indicate that the plant operates with higher efficiency compared to similar plants in the region, where PR typically ranges between 70% and 82%. The findings demonstrate that the Ramarothole Solar PV Plant performs well under the local conditions, though seasonal fluctuations highlight the influence of irradiance variability and potential technical inefficiencies. It is concluded that regular preventive maintenance, improved monitoring of solar irradiance data and better alignment with national energy planning are necessary to sustain high performance and to optimize future solar PV projects in Lesotho.Item Open Access Potential analysis for solar photovoltaic-Thermal (PVT) systems in educational institutions(National University of Lesotho, 2025) Khoete, Lineo Grace; Thamae, Leboli ZakEducational institutions in Lesotho, such as the National University of Lesotho (NUL), face challenges related to energy reliability and the increasing cost of grid electricity. These issues highlight the need for more resilient, sustainable and cost-effective energy alternatives. Solar photovoltaic (PV) systems are used for electricity generation and solar thermal systems for heating purposes. However, the combination of these two technologies into a single photovoltaic-thermal (PVT) system remains largely unexplored within the education sector. Therefore, this study investigates the potential for PVT systems to meet the energy needs of the student residences at the NUL using the POLYSUN simulation software. The PVT system was designed to provide 5,000 litres of hot water daily at a target temperature of 50 °C for one case study residence, and its performance was compared against a corresponding solar water heating (SWH) system. The PVT system design utilised a collector area of 75 m², whereas the SWH system employed 50 m². A comparative assessment is carried out to analyse the systems in terms of technical performance, cost-effectiveness and environmental impact. Simulation results indicate that the PVT system achieves a solar fraction of 88% and generates 46,398 kWh of thermal energy annually. Further, the PVT system produces an additional 23,773 kWh of electricity each year, with 20,818 kWh to be used directly on-site. This results in energy savings of 72,615 kWh. It also attains a performance factor of 4.5 and an overall efficiency of 40%, comprising 26.7% thermal and 14% electrical efficiency. Environmentally, the PVT system significantly reduces carbon emissions, saving 38,951 kg of CO₂ annually (26,199 kg from thermal production and 12,752 kg from electricity generation). From an economic perspective, the PVT system requires an initial investment of M1,425,000.00, which can be financed through 60% equity and 40% debt. However, this higher upfront cost is offset by improved financial performance over time. The PVT system achieves a levelized cost of energy of M1.62/kWh, a net present value of M1,546,935.60 and an internal rate of return of 17.7%. It also delivers an impressive return on the investment of 8.7% per year, a payback period of 9 years and annual energy cost savings estimated at M170,129.68. Therefore, the PVT system has the potential to meet the hot water demand and a portion of the electricity demand in educational institutions. To support broader adoption within Lesotho’s education sector, targeted policies, such as subsidies, incentives and accessible financing mechanisms, will be essential to offset the high initial costs.Item Open Access Planning, optimization and efficiency improvement of telecommunications solar plants(National University of Lesotho, 2023) Seeiso, Maama Ronny; Thamae, Leboli ZakMobile network operators (MNOs) in Lesotho have recently experienced an increase in deploying solar PV-powered base stations in off-grid and bad-grid areas to improve their network coverage to the most underprivileged communities. This justifies the need to model and design the optimal solar PV- battery systems to power telecom base stations (BSs) operating in high-speed technologies that meet both the MNO and regulator targets and act as enablers for other economic sectors in rural areas. This research primarily aimed to audit the existing Vodacom Lesotho solar PV-powered BSs through physical inspections, configurations assessment, and load profile analysis using historical data. Based on the audit results, retrofitting and parameter optimizations were implemented to improve major key performance indicators (KPIs), therefore maximizing telecom solar power plants' energy yield and solar PV arrays' performance ratios (PRs) in a cost-effective and environmentally friendly manner. Five solar PV-battery-powered BSs with different power and radio configurations were selected, and their KPIs, such as battery charging current, solar PV generator power, load current, and PR, were assessed, analysed and optimized for possible maximum energy yield. The Makebe BS improved charging currents by 15% with no improvements in other KPIs. The Malimong BS increased charging current by 23%, current from the solar generator by 12%, power by 11%, and PR by 3.31%. Mmasemouse BS showed an improvement of 34% in charging current, 19% in harvested current, 17% from the generated power after rewiring and optimizations, and 7.31% in PR. After replacing the faulty batteries and conducting a parameter optimization at Ha Tlhoro, the Tlhoro BS solar plant increased charging current by 60%, harvested current from the solar PV generator by 90%, generated power by 46%, and PR by 20%. After integrating two standalone solar arrays into one, rewiring, increasing the charging current limit and replacing faulty batteries for a high-capacity solar-powered BS in Kolo, it improved solar PV generator current by 7%, battery charging current by 19%, solar PV power by 40%, PR by 19% and able to reach 100% state of charge (SoC). One high-capacity and grid-powered BS in an urban area was assessed and dimensioned for grid-to-solar migration with a 20.8 kWp solar PV array, 27 kW solar PV charge controller, and 1200Ah backup batteries storage for 0.5 days of autonomy using the month of June, which has the lowest peak sunshine hours (PSH) as the design month for maximum system reliability.Item Open Access Optimized network planning of electrification projects in remote areas of Lesotho(National University of Lesotho, 2021) Motiki, Thuso Stephen; Thamae, Leboli ZakThe United Nations has, in 2015, adopted an urgent call for action by all countries for the implementation of Sustainable Development Goals (SDGs) which among them is access to affordable, reliable, and sustainable energy for all (SDG7). The call led to an increase of 120 million people gaining access to electricity each year but declined in 2020 and 2021 due to the coronavirus pandemic. So far, tools have been developed and several approaches have been applied to solve rural electrification problem but they often neglect the important spatial information such as population distribution which is one critical drawback. These data are important for the design of electrical networks hence when neglected lead to systematical capital investment miscalculation. The proposed strategy in this study utilizes a Geographic Information System (GIS) and terrain analysis to create an optimum electric network topology of the proposed case study involving the rural areas of Butha Buthe district in the mountains of the Kingdom of Lesotho. Furthermore, the geospatial-based procedure for rural electrification planning will be able to select and design an effective energy system for the defined geographical region to identify the least-cost solution to the existing national grid of non-electrified communities. The simulation tool to be used in this study, herein called GIS for Electrification (GISEle), focuses on data analysis and exhausts all means leading to the identification of the optimal techno-economic solution where energy lacks. The collected spatial data is exploited to identify populated areas and subdivide them into clusters thereafter designing the electrical network connecting those clusters with minimized costs. The performance of the procedure has been tested in 10 villages in the rural areas of ButhaButhe, Lesotho. The analysis shows that the geospatial tools are very important but work best on the application as per the need of the specific demand of the client. In this case, the model demonstrated huge achievement and design time saving as the electrical designers do not have to re-design the network when designs are now transferred from paper to the ground. GISEle looks at all aspects from terrain to road access making it easier for operation and maintenance purposes. The total GISEle costs for Makhunoana 1 community council are M1, 117, 517. 12 which is lower than the cost price of M2, 475, 000 from the Electrification Master Plan (EMP). The overall costs for Ts’a-Le-Moleka community council using GISEle tool are M1, 385, 229.12 and they are lower as compared to the overall cost of M1, 815, 000 from the EMP. Furthermore, the overall GISEle electrification cost for Makhunoana 2 are M1, 107, 741.12 with a slide difference from M1, 095, 000 from EMP study. Lastly, Ntelle GISEle electrification costs are M2, 004, 440.96 and are also lower compared to the M2, 070, 000 from EMP. This figures mean that GISEle is more preferable than EMP and more viable as the electrification planning demonstrated detailed design not estimates as the case for EMP.Item Open Access Optimization of the choice of solar minigrid architecture and management in Lesotho(National University of Lesotho, 2020) Kao, Moruti Clement; Hove, TawandaInstallation and maintenance of the solar photovoltaic systems for power generation is highly discouraged by the high costs of storage units resulting from the traditional approach of sizing the systems. In order to reduce these costs, Solar PV systems sizing using a time-step approach is used in this study as opposed to traditional approach. Comparison of the traditional and timestep approaches used for sizing solar PV systems was performed and showed that time-step approach is the most cost-effective way of sizing the PV systems. The time-step approach is very important in this study since it addresses the country’s lack of progress in mini-grid establishment regarding appropriate mini-grids architectural combinations versus costs best for Lesotho. The primary aim of this research work was to develop a comprehensive computer-based model to be used for performance and optimization of mini-grid systems in order to reduce the system costs, operation costs as well as enhancing the systems reliability. This involved developing an approach to modelling hourly load profile in the absence of historical consumption data and finally determine the best mini-grid system architectural combination which should be used in Lesotho, based on considerations of reliability and cost of energy. The current work successfully developed a simple computer-based program for optimally sizing, performance prediction and economic analysis of mini-grids systems. It shows how optimally sized solar mini-grid systems are determined by the model. The only data required to differentiate between mini-grid systems is the daily energy load as well as its hourly distribution and the desired supply reliability. The current work uses Sehong-hong mini-grid among sites identified by Sustainable Energy for All (SE4ALL) in Lesotho’s mountainous districts and the objective function used for determining the cost effective solar mini-grid architectural combination best for Lesotho is the Levelized Cost of Energy (LCOE). The study also explores several diesel dispatch strategies on system performance and energy cost. The study presents an optimised design and performance of solar mini-grid architectural configurations comprising solar PV array, solar inverter, battery bank, battery chargers as well as diesel generator. In this study, system component sizing is defined in terms of daily-energyload related dimensionless variables, 𝑃⁄𝑃0 for PV array size, 𝐵𝑐𝑎𝑝⁄𝐿𝑑𝑎𝑦 for battery size and 𝑄𝐷𝐺⁄𝐿̅ for diesel generator size. This allows generalization of the design for similar locations and similar hourly load profiles. Results of simulations using the study method show that the most cost-effective configuration for mini-grid systems in Lesotho comprises a PV array, a battery and a diesel generator, and should operate at a high solar fraction. For 100% supply reliability, the optimum system comprises solar PV array size (𝑃⁄𝑃0 = 11.2), battery bank size (𝐵𝑐𝑎𝑝⁄𝐿𝑑𝑎𝑦 = 1.8) and diesel generator size (𝑄𝐷𝐺⁄𝐿̅ = 2.2), operating at 83 % solar fraction and at LCOE of 0.62 USD/kWh. For 99% supply reliability, the optimum system has 𝑃⁄𝑃0 = 3.9, 𝐵𝑐𝑎𝑝⁄𝐿𝑑𝑎𝑦 = 0.292 and (𝑄𝐷𝐺⁄𝐿̅ = 2.2), operating at 85% solar fraction and at LCOE of 0.30 USD/kWh. It is opined to go for 99% reliability ahead of 100% reliability as only a 1% increase in reliability results in 54% cost increase. The used dispatch strategy in this study for the diesel generator is charge cycling strategy.Item Open Access Optimization of Mantsonyane and Semonkong mini hydro power stations by hybridization(National University of Lesotho, 2020) Lepheana, Bahlakoana David; Thamae, Leboli ZakThis paper shows the optimized design and performance of a hybrid energy system for the following study sites, Mantsonyane and Semonkong in Lesotho. The main objective is to design a hybrid system with Low Cost of Energy (LCOE), high Renewable Fraction (RF) and reduced carbon emissions from a diesel generator at Semonkong hydro-diesel hybrid system. This study employs HOMER Pro simulation software to demonstrate the performance of the Mantsonyane and Semonkong hybrid renewable energy systems. The proposed Semonkong system design is made up of 360 kW of solar PV array, 100 kW wind turbine, 500 kW inverter, 1 MWh battery storage, 180 kW mini hydro and 410 kW diesel generator with a Load Following (LF) dispatch strategy. The simulation results indicate the environmentally friendly system with a renewable fraction of 97.3% which also reflects the high utilization of renewable energy in the system and the remaining small portion is diesel generator. The total energy produced is 1,978,099 kWh per year out of which 25.2% is contributed by wind turbines, hydro power generation contributed 41.8% while solar PV supplied 31.6% and diesel generator injected only 1.42%. The LCOE for this system is $0.129/kWh and these results are taken at the solar irradiation of 5.44 kWh/m2, wind speed of 9.71 m/s, average flow rate of 1,595 L/s and the diesel price of $1.00/L. The project would demand an initial capital contribution of roughly $1.25M with a total NPC of $2.65M. The proposed Mantsonyane system design comprises of twenty-five wind turbines with a total capacity of 7.5 MW, one unit of 1MWh battery storage, 2 MW mini hydro turbine and a 2 MW converter. The simulation results show that the renewable fraction for the most cost effective system configuration is 100% with the LCOE of $0.149/kWh. The results were taken at the solar irradiation of 5.44 kWh/m2, wind speed of 9.71 m/s, and average flow rate of 1,731 L/s. This project would demand an initial capital contribution of roughly $22.8M with a total NPC of $45.2M. Sensitivity analysis is used to investigate the impact of variation in wind speed, solar radiation and river flow rates at Mantsonyane. The analysis indicates that a high COE is experienced when the plant is operating at a very low load with comparatively low O&M costs. It is also found that good river flow rates and high wind speeds result in a more affordable unit price. As for Semonkong site, the optimal solution shows a minimal impact from the instability of diesel price, river flow rate and solar radiation. The LCOE drops with the increasing wind speed and river flow rates. However, the diesel generator will remain part of the system in order to boost generation during dry season from July to September.Item Open Access Optimal sizing, performance prediction and economic appraisal of off-grid solar PV hybrid power systems in Lesotho(National University of Lesotho, 2020) Lepolesa, Selone Augustinus; Hove, TawandaThis dissertation reports about the development of and the application of a simple spreadsheet-based mathematical model for the sizing, the performance prediction, and the economic analysis of a PV-Diesel-Battery autonomous power supply system. The main objective was to find appropriate reliability level required of a mini-grid system in Lesotho that minimized the Levelized Cost of Energy (LCOE), and at the same time, supplied a satisfactory energy service. The goal was to determine the costeffective level to set for the energy reliability for mini-grids in Lesotho, such that the LCOE would not increase disproportionately with the marginal increase in the reliability level. The method used was to find the reliability at the minimum cost using the elbow of the graph. The simulation and performance analysis showed that there was an infinite number of combinations of battery, PV array and diesel generator size required to achieve a given supply reliability. It was observed that the conditions for minimum LCOE may not correspond to highest reliability and satisfactory energy service.Item Open Access Modelling and optimization of micro grids for rural areas in Lesotho (Component sizes for technical and economic feasibility)(National University of Lesotho, 2021) Fonya, Thabo SamuelThe study analysed different types of hybrid micro grids system configurations and found out the following to be both technically and economically viable: (a) PV with Levelised Cost of Electricity (LCOE) of R4.64/kWh, (b) PV/Wind of R5.03/kWh, (c) PV/Wind/Generator at R5.16 /kWh and lastly (d) PV/Generator of R4.80/kWh. These viable system configurations have more than 93.1 % renewables. All four technically and economically viable system configurations were found to be more sensitive to either price of diesel or inflation rate. As diesel price increased from R13.00/litre to R15.00/litre, LCOE increased from R5.15/kWh to R5.24/kWh. As inflation rate changed from 5.00 % to 6.50%, LCOE decreased from R4.64/kWh to R4.42/kWh. The most suitable system configuration has been found to both technically and economically viable is solar/generator with LCOE of R4.80/kWh and lower carbon emissions of 4843 kg/yr greenhouse gas emissions. For this solar/generator, NPV is R940 994.00, IRR is 18%, while ROI is 15.5% and payback period is 5.81 years. Any hybrid micro grid system that had hydro component in its system configuration was found to be not viable due to the high capital cost which contributed to high LCOE. The high cost of the system configuration that included the hydro component had been brought about by the high cost of civil works for erecting diversion weir for the micro grid power station.Item Open Access Measurement and determinants of energy poverty in Lesotho(National University of Lesotho, 2024) Lekola, Mathabela; Thamae, Retselisitsoe; Lekhooana, MositoEnergy poverty remains a significant barrier to sustainable development in Lesotho. This study assesses the prevalence of energy poverty and employs a multinomial logit model to analyse the determinants of energy poverty, using data from the Lesotho 2017 Household Energy Consumption Survey (HECS). The research study explores the impact of various socioeconomic and demographic factors on different categories of energy poverty during both summer and winter seasons. The statistical analysis was conducted using Gretl software, a robust, open-source tool specifically designed for econometric analysis. Gretl facilitated the multinomial logit model, enabling the identification of key socioeconomic and demographic factors influencing various categories of energy poverty. The analysis reveals seasonal variations in energy poverty, with a higher incidence of energy poverty during winter, highlighting the increased energy needs. The key determinants of energy poverty include household income, settlement type, education level and gender of the household head. Relatively higher income levels and urban or peri-urban households are less likely to experience energy poverty, while low-income and rural households face higher risks. The education of household heads has an impact on energy poverty but was found to be inconsistent across the summer and winter models. The summer model showed that higher education was protective against extreme energy poverty, while in the winter model, higher education showed a higher likelihood of transitioning from the non-energy poverty category to the transitional and moderate energy poverty categories. The study also highlights gender disparities, with female-headed households being more vulnerable to moderate energy poverty, particularly in summer. Based on these insights, the study provides policy recommendations aimed at enhancing energy access and reducing energy poverty, including targeted support for vulnerable groups, strengthening rural energy infrastructure and promoting educational initiatives on energy management. The findings offer valuable contributions to the ongoing policy discourse as Lesotho prepares to evaluate its national energy policy, presenting an opportunity to integrate these insights into future strategies.Item Open Access Investigating viability of using solar thermal energy for optimizing the gas yields for biogas in Lesotho(National University of Lesotho, 2021) Lesenyeho, Tabempe Edgar; Hove, TawandaSelection of the solar thermal collector using the energy per dollar matrix, prevailing interest rate and the prevailing inflation rate is of paramount importance for decision-making for investment in solar-assisted biodigesters. This paper presents a comprehensive computer-based excel model on investigating the viability of using solar thermal energy for optimizing the biogas yields in Lesotho. The excel based model is used to analyze both the thermal and economic performance of the solar-assisted biogas digester.The model determines solar thermal performance,solar thermal collector size, solar storage size, as well as the surface area over which the heat losses occur in both the solar water heater and biodigester tank.It will further look into economic analysis of the system. In order to ensure maximum benefits, sizing of the solar thermal system has been carried out to give the optimum solution. Simulations have been performed on an hourly time step. Comparison of production of biogas with solar thermal energy and production of biogas without solar thermal energy were undertaken to find the effects of temperature on the production of biogas. It was found that the production of biogas is optimum at the mesophilic temperatures of 180 C to 300 C. Different collectors, both evacuated tube collectors and flat plate collectors which are valued by Solar Ratings & Certificate Corporation are ranked using energy per dollar matrix. The Sun power evacuated tube collector is the best collector used for system design since it has high energy per dollar of 25.3 kWh and low heat loss parameters. The Net Present Value is the objective function to optimize for the solar thermal system. The optimum collector area to deploy for 5𝑚3 biodigester is 16𝑚2, the optimum solar storage tank of 800 liters is required. The total cost of buying the collector and the solar storage tank is $1744.In Lesotho 1𝑚3 of biodigester requires a solar thermal collector area of about 3𝑚2.The optimum collector area gives a maximum Net Present Value of $1854.Moreover, the biogas produced is 396𝑚3 per annum with the percentage increase of extra biogas as 11.5% per annum. The project is economically viable with a Net Present Value of $1854, an Internal Rate of Return of 10.36%, a Payback period of 9 years, and a Benefit-Cost Ratio of 2.01. The project lifetime is 20 years.Item Open Access Integration of solar heating systems in the textile industry(National University of Lesotho, 2024) Leseeka, Litheba CatherineCurrently, fossil fuels are the mostly used source of thermal energy in the industrial sector in Lesotho. They provide the necessary heat for different industrial processes across a range of temperatures. Within the sector, the textile industry is a significant consumer of thermal energy, particularly for the wetting processes that require large amounts of hot water. As global concerns about climate change and global warming intensify, industries are required to reduce their carbon footprint and transition to cleaner and sustainable energy sources. This study investigated the techno-economic viability of integrating solar water heating systems at the Vishan Clothing Laundry facility in Maseru, Lesotho, using T*SOL simulation software. The study focused on three main points: solar thermal system design, performance analysis and evaluating the economic aspects of the proposed system. To determine the most efficient system for meeting the laundry’s hot water needs, six separate simulations were conducted for a comprehensive comparative analysis. From the simulations, the optimally designed system consists of Dimas SA RADIANT RSV 25 flat-plate collectors at 30° inclination angle with a collector area of 1,980 m2 and a storage tank with a capacity of 130 m3. This configuration achieves an efficiency of 54%, and a solar fraction of 89%, indicating a significant contribution from solar energy to the overall hot water production. The economic analysis under two different financing approaches shows that the system is economically viable. The proposed system under equity financing has a capital return time of 7 years, a positive net present value (NPV) of M 13,981,755, an internal rate of return (IRR) at 16.88% and cost of solar energy at M 0.831/kWh. Under equity-debt financing, the proposed system has a capital return time of 7.9 years, and amortization period of 10.3 years, a positive NPV of M 12,983,854, an IRR at 18.78% and cost of solar energy at M 0.872/kWh. These financial indicators demonstrate the economic feasibility and potential profitability of integrating solar heating systems in the textile industry. The study further highlights the need for further research to refine the system design and improve its performance. Most importantly, the study emphasizes the necessity of conducting in-depth energy audits to accurately determine the thermal energy demand of the facility. Such audits can probably provide more precise data, ensuring that the designed system can adequately meet the thermal energy demand of the laundry facility.