From the story above:
“South Africa seems primed for solar power. It has set the goal of having 10,000 GW of electricity come from renewable energy resources by 2013″

Quite certain that South Africa does NOT plan to install 10TW (terrawatts) of solar generation capacity (i.e. – 10x the entire US or Chinese generation capacity), but instead wants to generate 10,000 GW HOURS (GWh). The amount of confusion that journalists cause to layman because they either don’t understand the difference between capacity and generation units, or – more likely – because they just get lazy and don’t probably explain and/or label them, is quite serious.

To calculate how many installed GW of solar generation capacity that would take, do the following:

(10,000GWh / annum)/(8,760 hours / annum) / (capacity factor of X%)

A reasonable capacity factor for PV in South Africa would be something like 15-20%, which would give a required installed solar PV capacity of around 5.7-7.6GW. Other renewable technologies will have different capacity factors.

So CleanTechnica, PLEASE start using proper units so that many of your readers don’t get confused. And that does NOT mean just saying how many homes’ electricity requirement that equals, unless you clarify how much electricity homes in country/region X use, and whether you have calculated the actual output of the plant, not just the installed, name-plate capacity