In a rapidly changing territory, energy networks must be increasingly responsive and flexible. New models of multi-fluid management and energy production are being created and developed on national and international level. This involves the use, monitoring and supervision of many sensors that reports lot of data. This paper deals with the secure management of large amounts of data within the context of smart grid. We propose a solution based on proxy re-encryption designed primarily to allow decryption delegation, which allow a neat management of large amount of data while respecting the GDPR (General Data Protection Regulation) and security standards.