The problem with many of these IPPs is that they produce too much power for the locations they're in, which means power has to be exported onto the Eskom transmission grid. This is good, but the IPP funding only covers their own build and connect tion to the closest Eskom line. Whether this line actually has the transfer capacity to handle that load is immaterial to the IPPs.
This puts Eskom in a tight spot. It costs a ,metric crapton to build new lines. They also can't upgrade the existing lines without switching off areas for months at a time. Some work can be done by live line contractors of course but this is insanely expensive and dangerous. So what is the alternative? Organize new servitudes which crosses farms and this causes maaaaaassive issues. Farmers hate Eskom and with due cause, but it leaves the company with little room to work in. Stakeholder management and public participation is key, we all saw what it did to etolls.
So I can see why Eskom won't connect some IPPs.