Heat reflecting coating on the roof makes even Leeward Oahu houses cool, and it is way cheaper that reroofing. 
 Split air conditioners in Japan are about $1,000 but use only about 3 kwh a day running 24/7.  Even though Japan rates also about 30 cents a kwh, 700 sq ft air conditioned apartment, 24 hours a day is $15 a month.  If it were 10 cents a kwh like on the mainland, it would be $5 a month.  No joke.  I have had one for 7 years and used an electricity meter.  It is silent.  
Full size refrigerator is about $1200 and runs for 20 kwh, $6, a month.  What everyone in Hawaii really needs to do is replace inefficient air conditioners and refrigerators with efficient ones.
Oh, and LEDs.
I cut my electricity use in half by doing the above.