Solar panels still provide power on cloudy days.

In fact under certain conditions they’ll produce more power than under full sun - solar panels drop in efficiency when they are too hot. (Yes I know this isn’t normal; normally full sun will produce more power, but some people don’t know cloudy days are fine for solar energy production.)

They did talk about that. The article said that in some cases solar producers have had to curtail production because the thermal plants needed to keep running. Solar will generate a lot during the day that might not otherwise be used, the battery allows that surplus to be stored until it's needed. They also mentioned that more solar projects are being constructed.

Hawaiian Electric's modeling suggests it can reduce curtailment of renewables by an estimated 69% for the first five years thanks to Kapol Energy Storage, allowing surplus clean electricity that would otherwise waste to get onto the grid.

I'd rather have brownouts, and I don't think either is likely.

Great but the article didn’t address how they are making up for that lost production capacity besides stating “renewables”

This is just non-sense. No general understanding of principals, or local understanding of context.