PV modules and ballast arm assemblies are mounted onto a torque tube suspended from a support structure. The support structures allows torque tube, and mounted PV modules and ballast arm assemblies, to freely rotate. The ballast arm assembly includes a drive mechanism, an arm and a ballast. The drive mechanism allows the adjustment angle between the PV module and the arm and ballast to be changed. Changing the adjustment angle causes the torque tube, and mounted PV modules, to freely rotate to a different orientation angle in order to balance the moments of PV modules and ballast arm assemblies caused by gravity. The orientation angle can be changed throughout the day by changing the adjustment angle in order for the PV modules to track the sun.