Bi-positional exposure (discrete tracking) of PV-modules (or flat-plate solar-thermal collectors) allows increased efficiency due to a prolonged daily interval of performance and reduced incident angle. A stand-alone PV-module in the regime of the bi-positional tracking is the most effective. If such PV-modules are concentrated into a row (and farm), then they will mutually shadow each other during some transient shading interval in the sunny morning and in the sunny evening. For that reason, a bi-positional PV-row performs somewhat less effectively and its usage may be problematic. Therefore, the usage of a bi-positional PV-row is analyzed and discussed in this paper. In the row the gain (increased efficiency) of discrete tracking depends on the relative distance between the tracked modules and the deflection angle. A row of PV-modules with a bi-positional exposure is beneficial if the distance between the neighbor modules surpasses the two-three values of their width. (C) 2009 Published by Elsevier Ltd.