Recognizing that reality, state officials in recent years have gone back to encouraging the use of small-scale energy systems. To manage the supply and demand of electricity, for example, Hawaii offers up to $4,250 to homeowners on Oahu, home to about 70 percent of the state’s population and Honolulu, to install home batteries with their solar systems, defraying as much as third of the cost of doing so. Utilities can tap those batteries for…