At the minimum, you need
A. 2.5 kva pure /modified inverter charger
B. Four 200 Ah gel/maintance free or lead acid batteries depending on your pocket.. (very important aspect)
C. Cabling
D. Good charge controllers. insist on MPPT charge controllers
E. Change over switch. I use katko
F. You mentioned off grid, so you shall need four 200 Watt solar panels or equivalent
This is a good offgrid system