We address the question of mean biomass volumetric productivity optimization,which originates from the simplification of dynamics of microalgae in a batchbioreactor process with light incidence. In particular, the stability of the model isanalyzed, some optimality necessary conditions for the nonsmooth optimizationproblem obtained through the inclusion of different photoperiods are studied,and the model is applied in the particular case of Chlamydomonas reinhardtiimicroalgae to validate our results.