Battery back-up is for those times when there is no power from the grid. This takes the form of localised power to run a few crucial items, usually off something like a multi-plug, alternatively, it gets wired through your electrical distribution board and runs all the systems required throughout the site. The size of a battery back-up system depends on what you want to run, how much power those appliances draw, and how long you want to run them for in the event of a power failure.
If your intention is to eventually move to a hybrid system, then the DB wired system is the way to start and then add PV panels later. It is not possible to have power when there is load shedding using a grid-tie system, this system uses the grid as a reference point, as such when there is no power from the grid, you have no power despite having panels! the way around this is to design a hybrid system https://www.green-grid.co.za/solar-option/hybrid/
Most systems need to be designed around individual requirements, especially on the commercial front where needs differ vastly around the functions of each business. Contact our team for advice or a quote, today.