The available grid connection duration depends on the battery capacity and grid-connected power. For instance, if the main unit's battery is fully charged with a capacity of 2048WH, and the grid-connected power of 200W is selected , the grid connection duration can be calculated as follows: Grid connection duration = Battery capacity * Conversion efficiency / Grid-connected power (2048 * 0.9 / 200 ≈ 9.5 hours).