Despite remarkable economic growth and development in recent decades, Rwanda has been still facing energy crises and challenges. Although the country has considerable energy assets, less than 10% is utilized for its local electricity needs. Currently, national installed generation capacity is estimated at 221 MW, for a population around 12 million, and electricity access is estimated at 51% (37% grid and 14% off-grid networks). About half the population is without electricity access while the grid-connected users face high electricity tariffs and frequent power outages (blackouts). The national grid itself is also experiencing high losses. This paper used the HOMER software for modeling the optimal, sustainable, reliable, and affordable photovoltaic solar technologies as energy solutions for all (off-grid and on-grid users) in Rwanda. The selection and recommendation of a suitable photovoltaic (PV) solar technology depend on its annual electricity production capacity, electrical load, renewable energy penetration percentage, economic viability, feasibility, affordability, carbon footprint, and greenhouse gas emission level for climate change considerations towards a clean and greener future. The results show that the least cost of energy (LCOE) for electricity production by each of the solar PV systems with storage, PV-grid-connected household, and PV-grid connection with storage was 67.5%, 56.8%, and 33.9%, respectively, lower than the normal electricity tariff in Rwanda. The PV systems with storage proposed in this paper could be effective in increasing national energy resource exploitation, providing affordable and reliable energy access to all citizens.

Photovoltaic microgrids provide free renewable energy solutions for Rwandans. Although solar technology keeps on its advancement, hydropower remains the principal power source in Rwanda. Other renewable power sources include wind and geothermal energies that are not yet fully exploited. Nonrenewable sources in Rwanda including methane, peat, thermal, and fuels are also used for providing energy solutions for the citizens. Rwanda Energy Group (REG) sets the energy strategic plan since 2015 for achieving the minimum of 512 MW of energy production in 2024/2025 to meet the total energy demand. The plan predicted 52% for grid-connected and 48% for off-grid (standalone) connections. The literature survey and data analysis collected on site were used to evaluate and determine the best cheaper microgrid model from the three comparison case studies for the household in Rwanda. The study focused on the economic power generation model mainly based on solar resources to minimize the electricity cost and provide income for the excess energy produced. Moreover, the study resulted in a low-cost (four times cheaper), reliable, and affordable grid-connected PV and battery microgrid model for a residential home with a minimum daily load of 5.467 kWh. The simulation results based on economic comparison analysis found the levelized cost of energy (LCOE) and net present cost (NPC) for each power-generated model by using Hybrid Optimization Model for Electric Renewable (Homer) pro software. The results show that the LCOE for electricity production by each of the Grid connected-PV-Battery system, Diesel GenSet-PV-Batteries, and PV-Batteries systems was 0.0645 US$/1 kWh, 1.38 US$/1 kWh and 1.82 US$/1 kWh, respectively, compared with 0.2621 US$/1 kWh, the current residential electricity price (2020) for Rwanda.

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This paper describes an audio digital signal-processing toolkit that the authors develop to supplement a lecture course on digital signal processing (DSP) taught at the department of Electrical and Electronics Engineering at the University of Rwanda. In engineering education, laboratory work is a very important component for a holistic learning experience. However, even though today there is an increasing availability of programmable DSP hardware that students can largely benefit from, many poorly endowed universities cannot afford a costly full-fledged DSP laboratory. To help remedy this problem, the authors have developed C#.NET toolkits, which can be used for real-time digital audio signal processing laboratory. These toolkits can be used with any managed languages, like Visual Basic, C#, F# and managed C++. They provide frequently used modules for digital audio processing such as filtering, equalization, spectrum analysis, audio playback, and sound effects. It is anticipated that by creating a flexible and reusable components, students will not only learn fundamentals of DSP but also get an insight into the practicability of what they have learned in the classroom.

The remote location and many islands in Africa are experiencing a big power shortage and blackouts and they greatly necessitate electric power from standalone photovoltaic microgri­d. In Rwanda, off-grid solar systems are at their infancy level and their affordability for the rural population requires thorough support and incentives. In this process, the Government of Rwanda (GoR) has set a program to subsidize the cost of the system in a rural household power access projects suit to their socio-economic metric known as ‘Ubudehe’ which would determine the required financial support from other poverty reduction programs in a country. The design of a standalone photovoltaic microgrid is aimed to find the cheapest way to go for either a single rural house or a group of 200 rural houses with similar load demand as a long-term solution to their local energy challenges. The models resulted in a Levelized cost of energy, least cost of energy (LCOE) of 1.51US$/kWh for a single home while the LCOE for the group of houses load equals 1.45US$/kWh. The net present cost (NPC) for a single home and multi-user load are respectively equal to 5,625US$ and 1,079,210US$. These results conclude the efficacy of the group sharing load demand model design to provide green energy solutions to the mid-and low-income rural population in Rwanda.