The end-of-charge voltage threshold is slightly dependent on the battery technology.

For vented lead-acid batteries it should be  2.23 V/element, while for sealed batteries with recombination catalysator it can be raised to 2.25 V/element  (manufacturer recommendation).

According to manufacturer data sheets, the end-of-discharge threshold may depend on the discharge current, due to internal resistance voltage drop. Nevertheless, this applies in back-up use with high currents (discharges in one hour or less). With  solar use currents are usually far less and this effect can be neglected. PVsyst - as usual solar regulators - doesn't take it into account and proposes a fixed threshold voltage.