June 16 (Reuters) - Shares of U.S. solar energy companies tumbled in extended trade on Monday after Republicans who control the U.S. Senate Finance Committee unveiled changes to President Donald Trump's sweeping tax-cut and spending bill that would phase out solar, wind and energy tax credits by 2028.

Shares of Enphase Energy ENPH.O, which makes solar inverters, dropped 15% in after hours trade. Solar panel sellers Sunrun RUN.O and SolarEdge Technologies SEDG.O both tumbled more than 20%. First Solar FSLR.O lost 9%.

The modified text of Trump's "One Big Beautiful Bill Act" also extends tax credits for hydro, nuclear and geothermal power to 2036.

Those and other changes will be debated by Senate Republicans as they try to move forward on an aggressive timeline to pass the legislation ahead of the July 4 U.S. holiday.

The potential blow for solar companies comes amid already weak U.S. residential demand for solar, due in part to high interest rates and metering reforms in top market California, which have reduced the credits customers receive for feeding excess electricity back into the grid.