The state-owned Public Investment Corporation (PIC) said it has taken 20% stakes Ilanga and Xina power stations in the Northern Cape Province.
The PIC, which buys bonds in renewable energy projects, said it will also lend R600m to the Ilanga project.
Power utility Eskom, which provides virtually all of South Africa's power, is facing a funding crunch as it races to bring new power plants online to stave off electricity shortages.
The chronic energy shortages are pushing the government to seek alternative sources of electricity from Eskom's fleet of coal-powered stations that take much longer to build.
With year-round sunshine and kilometres of windswept coast in SA, investors are warming to the renewable energy potential to ease the regular blackouts that are strangling industries from mining to manufacturing.