Effective Jan 1, 2010, all new single family dwellings in the state of Hawaii are required to have a solar water heater installed (Hawaii Revised Statutes §196-6.5). The law does allow for a variance, if a homeowner does not want to install solar water heater.
For example, a gas tankless water heater + another appliance is allowed in lieu of a solar water heater. With regard to the requirement that the gas tankless heater be UL Approved, the energy specialist at the state emailed me saying they were not enforcing this provision (since to their knowledge, no gas tankless water heating appliance has received UL certification) and were accepting all gas tankless models. Also, a Rinnai tankless heater sales rep i spoke to at Fergusson confirmed state was accepting his tankless heater.
Link to the Hawaii State Dept of Business, Economic Development and Tourism (DBEDT - Solar)
Link to DBEDT - Variance to Solar Water Heater information
Interestingly, the requirement for having a solar water heater installed is not found within our Building, Zoning, Housing or Energy Codes. It was simply required by a new state law.
