Energy storage is essential for enhancing the stability, efficiency and sustainability of the modern energy supply chain. It can help reduce the dependency on fossil fuels and increase the use and market penetration of renewable energy sources such as wind and solar power, which are intermittent and variable. The most common technology for short storage times (minutes to days) is electrochemical energy storage, and more specifically lithium-ion battery energy storage systems (BESS). In line with the EU ambition for more sustainable electric vehicle batteries, it is likely that second life applications and repurposing of electric vehicle batteries will increase. One of the main challenges for the deployment of BESS is the fire safety of lithium-ion batteries. Today, there is a lack of national guidelines in Sweden for how to design a BESS in terms of fire safety, which causes uncertainty. Without national guidelines, each municipality and local fire and rescue service must develop their own advice, which may result in inconsistent and costly solutions with a varying degree of fire protection. The aim of this study was to produce national guidelines for the fire protection of BESS. The guidelines were produced by literature searches, review of relevant laws, regulations and standards, review of international guidelines, workshops, information retrieval from project partners and through studying lessons learnt from previous incidents. The produced guidelines (found in Appendix C, in Swedish) are formed around three application categories, based on the type of application and user, which reflect the size of the BESS. For the first category, BESS for single-family home use, guidance is given for separated placement of BESS, remote fire alarm, and separated ventilation. For the second category, BESS for multi-dwelling blocks or businesses, recommendations regarding placement, detection and ventilation are increased. It is also advised to have an installation that allows the fire and rescue services to ventilate fire gases without opening doors and that emergency response plans are produced. For the third category, BESS for large-scale commercial applications and mobile BESS, some further requirements are introduced. They include risk analysis, separate building and fire cell demands, as well as recommendations for CCTV and gas monitoring as well as fire hose connection. The guidelines assume that current national laws and building regulations are complied with. Additionally, insurance companies may have their own guidance which should be checked before installation. The guidelines produced in this project should thus be used as a supporting tool or when an increased level of protection is sought. The guidelines only address BESS with lithium-ion batteries. It was not included in the work to evaluate whether special requirements should apply for reused or remanufactured batteries (second-life).