Domain-specific metadata schemas are essential to improve the findability and reusability of research software and to follow the FAIR4RS principles. However, many domains, including energy research, lack established metadata schemas. To address this gap, we developed a metadata schema for energy research software based on a requirement analysis and evaluated it through user testing. Our results show that the schema balances the need for formalization and interoperability, while also meeting the specific needs of energy researchers. Meanwhile, the testing showed that a good presentation of the required information is key to enable researchers to create the required metadata. This paper provides insights into the challenges and opportunities of designing a metadata schema for energy research software.