I agree with Nigel.
There are lots of factors which affect what would make a tracking system worthwhile, and my cynical view is that the installers make money from installing more stuff, so they would say that, wouldn't they? Actually working out what is the best value for money is really difficult. In some places, there can be partial shading of the panels and some arrangements handle that better than others. A tracking system could make that worse.
Arguably, a well designed tracking system will only use power for very short periods, so its daily energy consumption should be tiny.
If you've got no more roof space to put more panels, then more investment can't go on more panels, which would favour a tracking system over more panels. A solar farm may have fewer space constraints.