An Indiana Senate panel gave preliminary approval Thursday to a bill backed by the state's investor-owned power utilities that critics contend is an effort to muscle out smaller companies from the emerging solar energy market. The measure by Republican state Sen. Brandt Hershman was approved by thte Senate Utilities committee.Currently, solar panel owners who feed surplus energy into the power grid are compensated at a retail market rate, which supporters say enables them to pay off the expensive investment in solar within its useful life. Hershman's measure would drastically reduce that rate in five years, though it was amended Thursday after substantial opposition was voiced during a hearing last week.