[jeffalyanak]

Ideally build it in away from your house, as others have said, but in terms of actual safety systems:

-get a high quality BMS from a reputable source, it should supports current limits and thermal probes - configure current limits with as much overhead as possible, the less you drive them, the cooler they'll stay - make sure you have sufficient thermal probes inside key points in the pack(s) and that they're configured in the BMS to cut draw - add thermal fuses as well, knowing where to put these is important, too - house the packs so to minimize fire risk and cascading issues, especially if space is not a concern