In Spain, storage installations are legally defined as installations in which the final use of electricity is deferred to a time later than when it was generated, or which convert electrical energy into a form of energy that can be stored for subsequent reconversion of that energy into electrical energy. The owners of storage installations. Focusing on batteries as the most common storage method, at least at present, there are two different types depending on the energy supply source from which they are fed. A storage installation may be hybridised, provided that the requirements of Article 27.3 of Royal Decree 1183/2020 are met: 1. Hybridisation with a generation installation that already has an access and connection permit. In this. Based on the exponential development of energy storage, a call for aid for innovative energy storage projects hybridised with electricity generation installations using renewable energy sources. Their regulation is in a very incipient stage of development, there is hardly any express mention of them and relevant aspects of them remain without a legal framework. Despite this,.