What this means: within the 800 W / 1,000 W limits, a 2 kWh battery catches almost all of the midday surplus. If you're out during the day, the battery is worth it. If you're home during the day, Basic pays back fastest (≈ 3.4 years with mixed use).
When the bigger battery (Max) makes sense: on a dynamic (orange) tariff, prices change by the hour, cheap at midday and expensive in the evening. A bigger battery can then move more energy into the expensive hours. That extra benefit is not included above, because it depends on hourly prices and on what DEDDIE's specifications will allow for charging from the grid.