The present invention provides a string fastening device which allows a string to be threaded thereinto easily, facilitates tightening of the string and enables the string to be gripped softly and captured accurately. An indication from a user of a client device is received, to fetch over a data network media of a predefined type. The interruption device transmits a first signal to the release device via a power line and interrupts the transfer, via a power line, of energy generated by the solar module to the consumer if the interruption device does not receive, via said power line, a second signal from the release device within a specified first period. In preferred embodiments the first process comprises identifying a transition between said first and second sequences of data and deriving said timing data from the identified transition. The ratio of the cross-sectional area of each tip end portion to the cross-sectional area of each through hole is at least 0. A side plate on a left side to which a fixed tilt lock gear is attached is restrained from being elastically deformed by a rib.