Exoplanets sufficiently close to their host star can couple electrodynamically to the star. This process is known as electromagnetic star-planet interaction (SPI). The expected emission associated with this coupling is however difficult to observe due to the bright intrinsic emission of the stars. New methods and approaches are commonly work in progress. Therefore we aim to model the properties of SPI and its effects with semi-analytic approaches. Understanding of basic physical phenomena could help to identify signals of SPI in stellar lightcurves. The TRAPPIST-1 system is an intriguing system for the search of SPI because of its seven close-in planets. We show that SPI is indeed possible in this system and discuss its observability.