TUoS (Transmission Use of System) Charges
abbrev. Transmission Use of System Charges: TUoS charges are charges imposed by the grid operator on electricity generators for their use of the national grid. Part of the charges are designed to provide a market signal to developers to site wind farms in areas which will maximise efficiency of transmission and minimize necessary upgrading/addition to the national grid.
These charges may change over time due to the calculation method used and the location of the next generator on the grid. Thus a wind farm developer who might respond to the locational signal and initially incur a very low or even negative TUoS charge (i.e. actually receive a payment), might be forced to pay an significant positive TUoS charge if a large generator comes onto the system in a unfavourable location.