A threat to the future of the power grid.

Agreed.

The erratic nature of solar (and wind) also makes grid stabilization more difficult and more expensive. Generation has to match load. Load is erratic enough, but erratic generation makes the problem even harder. And more expensive.
Plus, you still need the generation capacity for when the clouds come out and the wind stops. That capacity has the same capital cost, which is not being recouped as fast due to less use. That spare capacity may also be in the form of really filthy stuff like diesel gensets, which can offset some of the benefits of renewables.

So someone who uses 100 kWh/day but, on average, generates 50 kWh/day, actually can cost the utility more than someone who just uses 50 kWh/day.

Little_Pig, add a little more content to you OPs in the future please; no one knows what you’re talking about or why unless the link is clicked.