Design and Modelling of PV Power Plant for Rural Electrification in Kayonza, Rwanda

Aims: This study aimed to design and model an off-grid SPV power plant with a storage system to meet the load required in Rwisirabo village.

Study Design: PV modules, inverter, charge controller, and Batteries have been designed, reproduced/simulated, and optimized for the rural area of Rwisirabo village in Kayonza district, Eastern Province, Rwanda.

Place and Duration of Study: The experiment has been done in the University of Rwanda/ African Centre of Excellence in Energy Studies for Sustainable Development (UR/ACE-ESD) High E-Tech Smart Grid Laboratory, Kigali, Rwanda between October 2020 and February 2021.

Methodology: Different methodologies have been applied to address the objective of this work. The site was identified, problems of the community were clearly stated, data required for the work was collected through various data collection mechanisms, and different literature was reviewed to identify the way to do this work. The data were collected from different sources and were analysed using a software tool (HOMER software) and simulated for getting a solution for the problems and challenged accordingly. An Off-grid Solar Photovoltaic Power Plant was established in Rwisirabo village in Kayonza District, Rwanda. This site has been chosen because, in the Mwiri sector, Kageyo cellule in Rwisirabo (Rwisirabo II) village is listed by National Electrification Plan (NEP) as the site to construct an off-grid solar PV Power Plant.

Results: Based on the load assessment and the design of the SPV system, the primary AC load of the village was 551,718 kWh/day with a peak load of 85.10 kW, the deferrable load was about 9.99 kWh/day and a deferrable peak load of 2.00 kW with the cost of energy (COE) $0.200/kWh were involved during optimization of the power plant. It also found that the peak demand of the community occurs from 18:00 to 20:00 hours because most of the household members would expect to be at their homes. The system items such as PV module, batteries, and inverter size have been found as an optimum system with 220 kW, 860 BAE PVS 210 batteries, and 110 kW respectively with a lifespan of 25 years of the project. The total net present cost (NPC), initial capital, operating cost, and Levelized COE for this off-grid SPV system were $903,829, $517,000, $17,522, and $0.200/kWh respectively. The monthly results of power generation in kW obtained after stimulation with software showed that the solar radiation is high in March, July, August, and September which brings more electric power generation. However, all months the power electricity remain generated. Results from simulation showed that this system generated mean power output of 220 kW and total production of 297,291 kWh/year. It approved that the system converter contributed the lowest NPC with $52,888.25 (6%), followed by PV modules that cost $244,284.28 (27%) and battery bank the first for this SPV system with a cost of $606,656.60 (67%). This optimal system uses 100% renewable energy.

Conclusion: It found that the implementation of an SPV system with battery storage in residential, commercial, and institutions in the area where the solar irradiance is concentrated across a country will reduce the cost of electricity and power interruption on the national grid. Therefore, further work is needed to optimize this system for rural electrification as well by integrating with other renewable sources available in the country and also extend the electrification to another area that is detached from the national grid.