AUGUSTA, Maine — A bill that aims to boost solar power in Maine faces long odds after failing to win the support of any Republicans on a key legislative panel.

The bill would address the contentious issue of “net metering,” a long-standing financial incentive used in Maine and other states to subsidize solar power. Environmental groups, power companies and local rooftop solar installers support the bill, which would let utilities sign 20-year contracts with residential solar customers. Instead of paying retail price, as under current billing practices, utilities would pay rates set by regulators.

The bill would also lift barriers on community-owned and large solar farms.

But Republicans on the Legislature’s energy committee opposed the legislation because of fears it would increase the electric bills of people who don’t have solar panels.