1. Energy, Electrical Systems and Electronics Laboratory, Department of physics, University of Yaounde I, Yaounde, Cameroon
2. Department of Physics, University Institute of Technology Fotso Victor of Bandjoun (IUT-FV), Bandjoun, Cameroon
3. Department of Physics, Faculty of Science, University of Ndjamena, Ndjamena, Chad
4. Carnot Energy Laboratory (CEL), Department of Physics, Faculty of Science, University of Bangui, Bangui, Central African Republic