The proper planning of the electricity economy has the objective to ensure the constant supply of electricity. Those responsible for the development of the electricity sector must ensure that consumption can be met especially during peak hours and it is thus incumbent to deal with two main subject matters: the supply of electricity, based inter alia on the expected installed generation capacity as well as the capacity of the transmission and distribution networks; the level of reliability of the electricity system which relies on proper maintenance and prevention of even unexpected malfunctions. The planner must also take into consideration electricity generation reserves which enable to carry out maintenance, cater for exceptional consumption demands and dealing with malfunctions. The planning of the electricity market is done based on trying to achieve financial optimization of the market place as a whole whilst understanding the cost of the non-supply of electricity. The more this non-supply costs, the higher level of reliability is required of the system and thus more electricity reserves are required.