​Peaking is made up of a group of stations that operate during peak periods or when the system is under duress, which is when demand is higher than what your typical station (known as base load power stations) can supply at the time. 
 
Peak load indicates the additional demand placed on the system over and above the normal base load requirements.  In South Africa, peak demand periods occur in the early mornings and early evenings. The morning peak is a combination of industrial and domestic demand whereas the evening peak is mainly domestic. In winter, record evening peaks occur with the increased use of domestic heating appliances.  In summer, air conditioning has the same effect.
 
Peaking power stations can react quickly to changes in demand and provide power to supplement that generated by base load stations. South Africa’s peaking power stations are hydroelectric, hydro pumped storage and gas turbine stations.