A solar power conversion device has an embedded security module for creating trusted metering data in relation to power generated and for delivering it to a metering data output. The security module might for example be constructed as an integrated circuit card constructed using semiconductor chip fabrication and assembly techniques to be integral with the solar power conversion device. The device might comprise more than one solar cell mounted on a panel to form an array. There may further be provided a panel management module for collating data, for instance from multiple cells, prior to transmission over a network via the metering output. The panel management module might comprise for example a subscriber identity module and the metering data output may provide associated mobile telephone endpoint technology so that the metering data can be transmitted over an air interface.