Jan 25 (Reuters) - Solar energy company Sunergy Renewables and blank-check firm Esgen Acquisition Corp cut the valuation of the combined entity to $390 million on Thursday after they amended the terms of their planned merger.

The companies had originally agreed on a $475 million valuation in April last year to list Sunergy on Nasdaq via the merger deal.

Esgen's backer, Energy Spectrum, has agreed to provide additional support to the deal in which the company would buy up to $15 million in convertible preferred equity securities, it said on Thursday.

Earlier, the energy infrastructure investment firm had agreed to invest $10 million. The firm had $1.85 billion of assets under management as of Sept. 30.

Florida-based Sunergy was founded in 2005 and provides solar and battery-based power as well as storage systems for residential use in Florida, Texas and Arkansas.

Blank-check firms, also known as special-purpose acquisition companies, have fallen out of favor due to an elevated interest rate environment and heightened regulatory scrutiny.

(Reporting by Jaiveer Singh Shekhawat in Bengaluru; Editing by Vijay Kishore)

((JaiveerSingh.Shekhawat@thomsonreuters.com;))