A system for power generation, the system comprising: a plurality of inverters each having a grid synchroniser, each said grid synchroniser to synchronise an AC output of a respective said inverter to an AC grid mains, each said inverter having a power input, a cable and an AC output for connection to said AC grid mains by said cable to provide a power supply input into said AC grid mains, wherein the cables of respective said inverters have different line impedances; the system further comprising: a grid sensor for said plurality of inverters, wherein the grid sensor is situated remotely from the physical locations of said inverters at a grid sensor location where AC current from each said AC output of said inverters is injected into said AC grid mains, an inverter sensor which is configured to sense an inverter characteristic of a said AC output of a said inverter and configured to transmit inverter data relating to said sensed inverter characteristic to said grid sensor and wherein each said grid synchroniser comprises: an inverter controller configured to control said AC output of said inverter, said controller including a data communications network receiver to receive grid data from said grid sensor via the data communications network, and wherein due to a said line impedance of said cable a voltage of said AC grid mains at said remote grid sensor location is phase shifted relative to a line voltage on said cable at said AC output, said grid sensor sensing a grid characteristic of said AC grid mains, wherein said sensed grid characteristic comprises a phase of said voltage of said AC grid mains at said grid sensor location and said received grid data indicates said phase, wherein said grid data comprises data relating to the grid characteristic of said AC grid mains sensed by said grid sensor, and wherein each said inverter controller is configured to control AC current output from a said AC output responsive to said grid data to synchronise phase of said AC current to said indicated phase, such that the phases of said AC currents from said AC outputs of said plurality of inverters are synchronised to said indicated phase irrespective of said different line impedances. a plurality of inverters each having a grid synchroniser, each said grid synchroniser to synchronise an AC output of a respective said inverter to an AC grid mains, each said inverter having a power input, a cable and an AC output for connection to said AC grid mains by said cable to provide a power supply input into said AC grid mains, wherein the cables of respective said inverters have different line impedances; the system further comprising: a grid sensor for said plurality of inverters, wherein the grid sensor is situated remotely from the physical locations of said inverters at a grid sensor location where AC current from each said AC output of said inverters is injected into said AC grid mains, an inverter sensor which is configured to sense an inverter characteristic of a said AC output of a said inverter and configured to transmit inverter data relating to said sensed inverter characteristic to said grid sensor and wherein each said grid synchroniser comprises: an inverter controller configured to control said AC output of said inverter, said controller including a data communications network receiver to receive grid data from said grid sensor via the data communications network, and wherein due to a said line impedance of said cable a voltage of said AC grid mains at said remote grid sensor location is phase shifted relative to a line voltage on said cable at said AC output, said grid sensor sensing a grid characteristic of said AC grid mains, wherein said sensed grid characteristic comprises a phase of said voltage of said AC grid mains at said grid sensor location and said received grid data indicates said phase, wherein said grid data comprises data relating to the grid characteristic of said AC grid mains sensed by said grid sensor, and wherein each said inverter controller is configured to control AC current output from a said AC output responsive to said grid data to synchronise phase of said AC current to said indicated phase, such that the phases of said AC currents from said AC outputs of said plurality of inverters are synchronised to said indicated phase irrespective of said different line impedances. an inverter controller configured to control said AC output of said inverter, said controller including a data communications network receiver to receive grid data from said grid sensor via the data communications network, and wherein due to a said line impedance of said cable a voltage of said AC grid mains at said remote grid sensor location is phase shifted relative to a line voltage on said cable at said AC output, said grid sensor sensing a grid characteristic of said AC grid mains, wherein said sensed grid characteristic comprises a phase of said voltage of said AC grid mains at said grid sensor location and said received grid data indicates said phase, wherein said grid data comprises data relating to the grid characteristic of said AC grid mains sensed by said grid sensor, and wherein each said inverter controller is configured to control AC current output from a said AC output responsive to said grid data to synchronise phase of said AC current to said indicated phase, such that the phases of said AC currents from said AC outputs of said plurality of inverters are synchronised to said indicated phase irrespective of said different line impedances.