Mary Beth Mandanas

Mary Beth Mandanas is Chief Executive Officer of Onyx Renewable Partners, responsible for the company’s overall strategic direction, growth and its operating performance. Mary Beth joined Onyx after serving as Chief Investment Officer for Sol Systems, LLC, a renewable energy infrastructure and impact investment company based in Washington, DC. Prior to her role at Sol Systems, Mary Beth held the position of Executive Vice President, Chief Strategy Officer, of CleanChoice Energy, Inc., a Washington, DC based company engaged in renewable energy retail supply and community solar, where she led strategic planning and was responsible for raising capital, banking/investor relations and establishing protocols for risk management and financial reporting. Prior to joining CleanChoice Energy, Mary Beth worked in corporate and investment banking for more than 20 years, principally with Credit Suisse First Boston and Citigroup, and focused in the power and utility sector. She worked with companies across multiple facets of corporate finance/strategic advisory transactions, which included capital raising, structured financings, liability/interest rate/commodity risk management, treasury operations, capital allocation strategies, dividend policy and mergers and acquisitions. Mary Beth earned her M.B.A degree from Vanderbilt University and graduated, magna cum laude, with a B.S. from the University of South Carolina.

Since July 2021, Mary Beth has served as an Independent Director, Audit Chair, on the Board of TortoiseEcofin Acquisition Corp III. In December 2021, she was nominated as an Independent Director for Energy Vault, Inc.