EXECUTIVE SUMMARY Deliverable D1.1 describes technical and non-technical requirements for SSB and lists all design parameters and related KPIs for LiM-SSB and AF-SSB, as defined in Task 1.1 and Task 1.2 of WP1 in the SOLVE project.In particular, CRF and PVS, the two main end-users of the project, provide the requirements for the cells according to the specific applications. These specifications overlap with the target of the call to define tentative KPIs for the cells developed within the project. Furthermore, CRF and PVS provide information about the cell module technical specification, which will be considered in the SOLVE prototype module design.In addition, CID defines the material specifications for all cell technologies under development, aligning with the requirements outlined in the call and provided by the project's end users. This definition is completed for each cell component in collaboration with the partners responsible for their fabrication. Additionally, the cell design parameters are specified in accordance with the needs of the partners handling the final assembly.Some of the data included in this deliverable is sensitive for the end users involved in the project, and as such, certain values have been kept confidential in this public version of the deliverable to protect their interests. However, all relevant data has been shared with CINEA’s Project Officer to ensure compliance with the project’s reporting and transparency requirements.