Solar power units still need to be hooked up to the grid and are rated accordingly. If the sun does not shine then the grid will have to provide the power so upgrades are needed whether or not you think the unnecessary. 

That's your opinion. It works 364 days of the year but the one day we have clouds then your opinion is wrong. The power has to be upgraded for that single day. 

So if we're talking only about 10 years perhaps you could air condition 20 rooms with no solar power. And you would break even with the benefits of supplying solar power to 10 rooms. Isn't that a better benefit? I'd rather have 20 rooms air conditioned for 10 years then to have 10 rooms air condition by solar power for 10 years. 

The cost could be the same in other words the investment would break even at that time. And at that time you'd be replacing the whole system's anyway. We need to run the surveys and do the analysis before deciding.

HECO could do the survey and analysis and then sub installers.