When it comes to solar power, and anything else with externalities, it's always best to be clear whether "can't" means "has no economic incentive to do so" or not.
In this particular case I'd say we are below the optimum level of solar, and it's just poorly aligned incentives.
edit: just to re-iterate this in clearer language:
If they "can" do something if they spent $X million dollars, and $X million dollars is less than the total amount saved by the economy of Hawaii by doing so, then it's not a technical problem, it's an economic co-ordination problem.
If the utility is going to lose money from doing something, because they can't capture all the resulting profit (like lower pollution meaning healthier people) then their employees will say they "can't" do something, as no-one gets promoted for making children healther on the utility shareholders dime. Even though they could if someone gave them the money.
There's lots of BS surrounding solar, and a main thread of it is to pretend that it's going to blow up the electrical grid. The only thing it destroys is some current utility business models.