measured pp i to the common network node such that net contribution of each individual network terminal can be determined alternatively as is illustrated in fig7 by means of wireless interface 123 the measured pp is communicated from each network terminal to a centralized facility of an operator of the common network node to which centralized facility the common network node also communicates the measured cp i per time unit of each network terminal wherein the operator determines the net contribution of each individual network terminal clearly in case the network terminal communicates the measured pp i to the common network node communication can be effected via the cable 102 or the wireless interface 123 it is also possible that in an embodiment of the present invention the power measurement is embodied in the form of a hybrid of the method disclosed in fig3 and 6 for some network terminals the power provided to the common network node is measured and determined at the network node while for other terminals the power provided to the network node is measured at the concerned network terminals fig8 illustrates a further embodiment of the alternative aspect of the present invention where the power provided pp i per time unit by the network terminal 103 to the common network node 101 is presented to a user of the individual network terminal on.