The STIX Solar Orbiter (SOLO) will be launched by ESA in 2018 to perform observations of the Sun, the inner heliosphere and solar wind. SOLO will fly towards the Sun and will have approached the star closer than any other previously launched spacecraft. SOLO’s three-axis will be stabilized and pointed to the Sun. Major breakthroughs in solar and heliospheric physics are expected from this mission. One of the SOLO’s instruments is an X-ray spectrometer/telescope (STIX) which is going to provide imaging spectroscopy of solar X-ray emission in a wide energy range. The Polish team from the CBK PAN is involved in the development of STIX electronics: IDPU and Aspect System, thermal modelling and simulations and EGSE.