Pacific Business News: Solar water heating is cost effective in all parts of Hawaii, according to a recent study. In the sunny areas of the islands, solar water heating can deliver hear at a cost of about 4 cents to 6 cents per kilowatt hour. In less sunny areas the range is 6 cents to 8 cents, said the report from the National Renewable Energy Laboratory. Electric customers in Hawaii pay at least 15 cents per kilowatt hour, depending on utility and customer class. The report said simple payback …