You don’t need to rebuild the whole grid. The power over night goes up, but that’s OK because night is currently very low usage. Sometimes that has meant turning off renewables as there is no where to put the power. In fact, this can cause negative power costs were they will pay you to take power! So next is where you need it, say a charging forecourt. But that is only during the day, so put in some huge batteries you charge over night. Top up with day time renewables if you can. All this already happens.