Sikkerhedssystem til alternative energiforsyninger

Use of prepayment mechanisms for alternative energy supply systems and monitoring connected devices. An energy supply system is, for instance, an alternative energy source, such as a photovoltaic array (320) and an overriding prepayment mechanism (312) adapted to control the supply of useable energy (electricity) to a point of use in accordance with predetermined prepayment criteria. The photovoltaic array (320) incorporates, integral therewith, an energy source controller (318) that is in communication with a corresponding controller (316) forming part of the prepayment mechanism (312).