Solar panels but buying batteries later - anyone tried?

Looking around at solar panel prices at Octopus and Costco.

14 panel array available for 5 or 6k which is my original target price.

Would then buy batteries the year after, at 3-4k.

Got a few expenses to pay in 2025, hence splitting this into two.

Any heavy downsides, apart from not being able to game the Agile tariffs?