Some 125 km south-east of Upington, in the Northern Cape, the solar collectors of the 50 MW Bokpoort concentrated solar thermal plant warm the heat transfer fluid that, in turn, heats the molten salts to create a giant battery. This makes it possible for the plant to produce electricity day and night. It is critical, though, that the sun shines, as cloud and rain means no production. In the sun-drenched Northern Cape, however, such conditions are infrequent.