An electric power generation control system includes: a variation prediction section configured to predict future variation, based on a variation log including a plurality of variation patterns obtained from past physical quantities and a variation pattern obtained from a newly obtained physical quantity; a balance calculation section configured to calculate energy balance between a electric power generation amount and a discharge amount with use of variation prediction in the variation prediction section; and a switching timing calculation section configured to calculate a timing of switching between various modes relating to electric power generation and discharge with use of the energy balance calculated by the balance calculation section.