There are so far 12 conferences planned for 2018 in South Africa. A summary is available via the IEEE Conferences Search:

Already held:

• IEEE 9th International Conference on Mechanical and Intelligent Manufacturing Technologies (ICMIMT), Cape Town, 10-13 Feb 2018 http://www.mimt.us/.
• Conference on Information Communications Technology and Society (ICTAS), Durban, 8-9 Mar 2018 http://www.ictas2018.com/.

• International Conference on the Domestic Use of Energy (DUE), Cape Town, 3-5 Apr 2018 http://energyuse.org.za/due/.
  3rd Biennial South African Biomedical Engineering Conference (SAIBMEC), Stellenbosch, 4-6 Apr 2018 http://www.sabec2018.com/.

Upcoming

• IEEE PES/IAS PowerAfrica, Cape Town, 26-29 June 2018 http://ieee-powerafrica.org/.
• International Conference on Advances in Big Data, Computing and Data Communication Systems (icABCD), Durban, 6-7 Aug 2018 http://icabcd.org/.
• IEEE South Africa Section Joint AP/MTT/EMC Chapter conference, TBA/August 2018.

• IEEE International Workshop on Signal Processing Systems (SiPS), Cape Town, 21-24 Oct 2018 http://www.sips2018.org/, http://sites.ieee.org/sips2018 Submission deadline: 02 Feb 2018.

Still accepting papers

• Open Innovations (OI), Limpopo, 1-3 Oct 2018 http://www.africaopen.org/ Submission deadline: 15 Jul 2018.
• IEEE 4th Global Electromagnetic Compatibility Conference (GEMCCON), Stellenbosch, 7-9 Nov 2018 http://www.gemccon2018.emcss.org/ Submission deadline: 22 June 2018.
• CEMi’18 Intentional Workshop on Computing, Electromagnetics, and Machine Intelligence, Stellenbosch, 21-24 Nov, 2018 http://www.cem18.computing.technology/ Submission deadline: 01 Aug 2018.

A special mention must also be made of the following conferences:

• IST-Africa 2018, Botswana, 9-11 May 2018 http://www.ist-africa.org/Conference2018/default.asp.
• SATNAC 2018, South Africa, 2-5 Sep 2018, held at the Arabella Hotel & Spa in the heart of the Kogelberg Biosphere Reserve near Hermanus, Western Cape, South Africa, http://www.satnac.org.za/ . Full paper submission  - Closed. Short paper submission - 20 June 2018. 

• South African Institute of Computer Scientists and Information Technologiests (SAICSIT) Conference 2018 to be held at Boardwalk Hotel, Convention Center and Spa from 26 -28 September 2018  http://saicsit.mandela.ac.za/ . Submission deadline: 1 July 2018.