Hawaii has become the first state to enact a law that says all new homes must have solar hot water heaters.

Legislation passed in June 2008 will require that most new one-family houses in Hawaii be equipped with solar water heaters, starting in 2010. The law cites Hawaii’s overwhelming dependence on fossil fuels and the impact on the state’s economy of rising petroleum prices as reasons for the requirement. The Hawaii Public Utilities Commission will be tasked with formulating specifications for acceptable installations.

The state passed the legislative mandate to support its goal of having 70 percent of the states' energy needs come from renewable energy sources by the year 2030. Hawaii Governor Linda Lingle believes the new law is "an important step towards energy independence."

In a move similar to Hawaii's, a bill signed by California Governor Arnold Schwarzenegger would provide rebates to residents and businesses to support the installation of 200,000 solar water heating systems in the state by 2017.

According to DOE's Consumer's Guide to Energy Efficiency and Renewable Energy, on average, if you install a solar water heater, your water heating bills should drop 50 to 80 percent.

Hawaii is the first state in the U.S. to mandate installation of solar hot water heaters. Israel has mandated solar heating systems since 1980; today about 90% of buildings there have them. Also, Spain requires new and renovated buildings to obtain 30%–70% of their hot water needs through solar means.