sun-synchronous satellites, as their name say, acquire scenes at the same solar time of the day when they pass over the same location. According to this site, sun-synchronicity is achieved by taking advantage of nodal regression and launching a satellite into an orbit where the nodal regression nearly exactly cancels out the daily change in the position of the sun over any point on earth, caused by the earth's orbit around the sun. This turns out to be, depending on the altitude of the satellite, about 95 to 100 degrees inclination.
The local time of descending node (or overpass time) is usually mentioned on the satellite descriptive documents. I would like to know how precise the solar time provided in those descriptive documents actually is and how to improve this precision based on potentially effecting parameters (altitude, latitude, longitude, day of year, age of the satellite). My understanding is that the main difference comes from local solar time vs mean solar time (see equation of time, up to 18 minutes), but I am seeking an order of magnitude of the other possible sources of dicrepancies between the announced overpass time and the actual local solar anywhere in the world.
I have several satellites in mind (the Sentinel's, MODIS, Landsat...), but I am particularly interested in PROBA-V. PROBA-V flies at an altitude of 820 km in a sun-synchronous orbit with a local overpass time at launch of 10:45 h. Because the satellite has no onboard propellant, the overpass times are expected to gradually differ from the at launch value. Examples of drift correction for satellites like Sentinel-2 are also welcome.