The invention concerns a power supply system suitable for converting and/or isolating charging power supplied to a vehicle charging system within battery operated vehicle. The system comprises an isolation transformer allowing at least one of electric isolation and voltage conversion between a primary power source and the vehicle charging system. The transformer comprises a primary side wherein one or more terminals of the primary side are electrically connectable to the primary power source and a secondary side, wherein one or more terminals of the secondary side are electrically connectable to the vehicle charging system, an EVSE control device electrically connectable to the vehicle charging system, a data communication line connected to the EVSE control device and connectable to the vehicle charging system, which data communication line allows, when connected to the vehicle charging system, transmission of control signals to the vehicle charging system, monitoring coupling between secondary side and the vehicle charging system and monitoring at least one parameter related to the charging status of the vehicle charging system during charging. The power supply system is further characterized in that the isolation transformer is a solid state transformer and further that the isolation transformer and the EVSE control device constitutes an integrated unit, i.e. physically arranged in common unit. The invention also concerns a computer program product for monitoring information from the power supply system.