A system is for producing products, advantageously solvents, by fermentation, advantageously multi-stage fermentation. The fermentation is complemented with pervaporation as in situ product recovery technology, combined with a multistage condensation of the permeate. The condensates are separately introduced in the downstream processing of the system to recover the produced products, advantageously solvents. The system for producing products, advantageously solvents, by fermentation is simplified and has an overall improved energy efficiency, compared to systems described in the art.