How to stop battery charging from the grid?

Hi there. I've recently installed a Growatt SPA 3000 inverter and battery system with an already existing solar array. I'm using the shine phone app at the recommendations to the installation instructions but I'm having a hard time navigating it. I've got the times set up for discharging the battery into the house when it's dark but the battery is charging itself back up from the grid when it's finished. Am I being dumb for missing something obvious?