Well that really depends on your requirements and the storage capacity. There are a number of options, plus several manufacturers, so we would normally ask you a number of questions in order to establish your requirements. We install systems from GivEnergy, Sofar, Solis, and Victron Energy.
Some battery systems are scalable and you could start with 2 Pylons = 4.8kwh, and later perhaps add another totaling 7.2kwh of storage.
Up to 8 Pylon batteries can be coupled together. For large off grid systems a hub is required, allowing up to 56 Pylon batteries.
Get in touch to find out more.