The daily movements of EUPOS®-Riga and LatPos permanent GNSS network stations have been studied. Time series of GNSS station results of both the EUPOS®-Riga and LatPos networks have been developed at the Institute of Geodesy and Geoinformation of the University of Latvia (LU GGI). Reference stations from EUREF Permanent Network (EPN) have been used and Bernese GPS Software, Version 5.0, in both kinematic and static modes was applied. The standard data sets were taken from IGS database. The impact of solid Earth tides on the site coordinate changes has been studied. The Moon and the Sun tide effect is a significant factor causing the GNSS station displacements together with the Earth crust local part. Earth tidal displacements have been obtained by modifying the routine of Bernese GPS Software computing tidal station displacements in accordance with the latest IERS Conventions.