Not a list,just four South Africans I could google quickly:

1. Siyabulela Xuza (Has an asteroid named after him too,Asteroid 23182/Siyaxuza)- Developed a cheap and safer rocket fuel as a teenager,has also done some work on micro-fuel cells. http://mic.com/articles/121025/only-24-of-sub-saharan-africa-has-access-to-electricity-this-man-is-changing-that
2. Mulalo Doyoyo - Developed a cement-free concrete-like material called Cenocell along with Paul-Biju Duval. https://en.wikipedia.org/wiki/Cenocell
3. Sandile Ngcobo - Invented the world's first digital laser. World’s first digital laser unveiled in South Africa - BBC News
4. Tshilidzi Marwala - Has three patents according to wikipedia for the following:
   1. David Mark Starfield David Milton Rubin. Tshilidzi Marwala Method and Apparatus for Radiation Imaging. IPC8 Class: AG01T100FI USPC Class: 25036302 [2]
   2. David Mark Starfield David Milton Rubin. Tshilidzi Marwala Coded Appertures Masks for Ration-Based Medical Imaging. WO 2008/14254 [3]
   3. Megan J. Russell, David M. Rubin, B. Wigdorowitz and Tshilidzi Marwala. (PCT/IB2009/006125) An artificial larynx. https://en.wikipedia.org/wiki/Tshilidzi_Marwala
   

Hope someone else can be more helpful particularly with inventors from other African countries.