NFPA 855 sets the rules in residential settings for each energy storage unit—how many kWh you can have per unit and the spacing requirements between those units. First, let's start with the language, and then we'll explain what this means. 5 of NFPA 855, we learn that individual ESS. . From small 20ft units powering factories and EV charging stations, to large 40ft containers stabilizing microgrids or utility loads, the right battery energy storage container size can make a big difference. In this guide, we'll explore standard container sizes, key decision factors, performance. . n house your critical battery assets securely. But who's actually reading about their requirements? Let's break it down:. . These containers are packed with Rackmount Storage Battery, which can store a whole bunch of energy and then release it when you need it.