NOVELTY - The apparatus has an energy sensor (16) measuring an energy parameter that is affected by an energy output of a renewable energy device. The sensor provides energy data indicative of the energy parameter to an electronic control unit (10) that uses the energy data to derive a profile of the changes over time in the energy parameter. The electronic control unit correlates the derived profile with a set of reference profiles, where each reference profile corresponds to a particular renewable energy source, and uses the results of the correlation to identify the type of renewable energy device.    USE - Identification apparatus for identifying a renewable energy device e.g. solar water heater, solar photovoltaic generator, wind turbine, and combined heat and power (CHP) generator, for deriving energy from a renewable energy source in a household and building energy management.    ADVANTAGE - The apparatus provides an accurate metering for the energy output of renewable energy devices and validates that the electricity has actually been generated from the renewable energy source.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a method for identifying a particular type of renewable energy device that derives energy from a renewable energy source    (2) a metering apparatus for use with a renewable energy device that derives energy from a renewable energy source, comprising an electronic control unit    (3) a method for metering a renewable energy device that derives energy from a renewable energy source    (4) a predictive control apparatus for use with a renewable energy device that derives energy from a renewable energy source and an auxiliary energy device that derives energy from an auxiliary energy source and an electrical appliance, comprising an electronic control unit    (5) a method for predicting an energy output of a renewable energy device that derives energy from a renewable energy source and controlling an auxiliary energy device that derives energy from an auxiliary energy source and an electrical appliance.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of an apparatus for controlling the heating of a domestic hot water cylinder.    Solar panel (4)    Pump (6)    Electronic control unit (10)    Timer control (12)    Energy sensors (16, 18)