Management Team

The Clean Power Finance management team, board of directors and advisers include Silicon Valley entrepreneurs and veterans from the solar, finance, and Internet industries. We focus our significant expertise and experience on driving the mass-market adoption of solar.

Executive Team


Nat Kreamer

President & Chief Executive Officer

Nat Kreamer, CEO

Nat is the President, CEO and member of the board of directors of Clean Power Finance. He is also the Chairman of the Board of Directors of SEIA (the Solar Energy Industries Association), the national solar trade organization. Nat’s original idea to finance solar for consumers led him to co-found SunRun, which he led as the company’s President and Chief Operating Officer. Nat was the President and member of the Board of Directors of Acro Energy Technologies, a residential and commercial solar integration company. He created the Chicago Climate Exchange market-making business for Pioneer Futures. Nat has also worked in power industry financial consulting at PricewaterhouseCoopers. An officer in the US Navy (Reserves), Nat is an Afghanistan war veteran, where he served in the Special Forces and was awarded the Bronze Star Medal. He received a “Champion of Change” award from the White House and a “Most Admired CEO” award from the San Francisco Business Times. Nat has a BS from Northwestern University and an MBA from Rice University.

Nicholas Mack

Senior Vice President, General Counsel & Corporate Secretary

Nick Mack

Before joining Clean Power Finance, Nick was the General Counsel and Corporate Secretary for Sungevity, a residential solar finance provider. Prior to Sungevity he was the General Counsel for Mainstream Energy, the parent of REC Solar and AEE Solar, the leading solar integration and distribution companies in the United States. Before entering the solar industry, Nick was the Deputy General Counsel at Yodlee, Assistant General Counsel in the Products Law Group at Sun Microsystems, and an Associate at Heller, Ehrman, White, & McAuliffe LLP. Nick has a JD from the University of California, Hastings College of Law and a BA from Georgetown University.

Steve Olszewski

Senior Vice President, Operations

Steve Olszewski

Steve brings extensive consumer financial services experience to Clean Power Finance. Prior to joining the team, Steve served as a Senior Vice President at Discover Financial Services, where he led the student loans business through the integration of The Student Loan Corporation and later oversaw the largest portfolio acquisition in Discover’s history. He also managed the six-fold growth in the deposits business, which became the company’s largest funding source. Prior to Discover, Steve led underwriting and servicing operations for GMAC’s auto insurance business and held operations strategy roles at Capital One. He is an alumnus of McKinsey & Company and Andersen Consulting (now Accenture), where he served a variety of clients in the energy and financial services sectors. Steve graduated from Wesleyan University with a BA in economics and government and holds an MBA from Northwestern’s Kellogg Graduate School of Management.

Vice Presidents and Managing Directors


Arash Boostani

Managing Director & Chief Solutions Architect

Arash Boostani

Arash has over 20 years of experience as a software and technology professional. He joined Clean Power Finance in 2009 and has been chiefly responsible for designing and building the CPF Tools software platform. Prior to joining CPF, Arash was the technical lead for the Wikipedia Usability Initiative, a project aimed at increasing the usability of Wikipedia for new contributors and reducing barriers to public participation. Arash spent the first 14 years of his career at the biotech company Genentech. He supported the Manufacturing, R&D, Engineering and Quality Assurance business units in various roles, including Software Engineer, Project Manager and Enterprise Architect. Arash studied Physics at the University of California, Davis.

Darryl Carbonaro

Managing Director & Deputy General Counsel

Darryl Carbonaro

Darryl has more than 15 years’ experience representing U.S and foreign lenders and borrowers in financing a broad range of assets, from hydroelectric facilities along the Danube to solar projects for a northern California school district. A former chemical engineer, Darryl began his legal career in the project and asset finance group at White & Case LLP in New York, then moved to Dechert LLP in San Francisco to focus on structured finance and securitization of commercial real estate. Prior to joining Clean Power Finance, he served as an assistant general counsel at Bank of America, where he helped launch the Bank’s renewable energy finance and energy efficiency finance groups. Darryl holds a JD from Pace Law School in White Plains, NY and a BS in Chemical Engineering from Drexel University in Philadelphia.

Sean Coletta

Managing Director, Renewable Capital Markets

Sean Coletta

Sean has raised or structured more than $1 billion in capital for solar projects, and led or assisted in developing and structuring thousands of residential, commercial and utility-scale solar facilities. At CPF, Sean is responsible for new residential fund origination and execution as well as commercial strategy. Prior to CPF, Sean was Managing Director of structured finance at CleanPath, LLC, co-founder of the Luminous Power Group, and Director of structured finance at FRV, LLC, formerly MMA Renewable Ventures. While at FRV, Sean was primarily responsible for raising non-recourse tax-advantage equity, construction debt, and term debt. Sean has financed state tax credit transactions, New Market Tax Credit transactions, sale-lease-back transactions, and partnership flip transactions on a portfolio and individual basis. He began his career at Boston Capital, where he specialized in structuring multi-investor tax-advantaged equity funds. Sean holds a Bachelor’s degree in economics from Tufts University.

Chris Wirth

Vice President, Marketing & Customer Experience

Chris Wirth

Chris leads CPF’s marketing and customer support and service initiatives. He has spent more than 20 years creating value for businesses and consumers at start-ups and Fortune 500 companies in the energy, technology, defense, and construction industries. Chris has spent the last six years in residential and commercial solar finance, as well as solar manufacturing technology. Previously, Chris managed international channels for a US subsidiary of defense giant BAE Systems PLC, and led channel marketing for Interline Brands, a national distributor of building supplies. Chris also spent time in client services for VML, a global digital marketing agency, serving clients ranging from Bayer to Intuit TurboTax. Prior to that, he led business development for a manufacturing service provider to Applied Materials. Chris has a BS in Marketing from San Jose State University and an MBA from the University of North Florida.

Board of Directors


Ed Feo

Managing Partner, USRG Renewable Finance

Ed is the managing partner of USRG Renewable Finance, the lending affiliate of the US Renewables Group. USRG is one of the nation’s largest, pure play private equity firms for renewable power, biofuels and clean technology infrastructure projects. Previously, he was a partner in the international law firm of Milbank, Tweed, Hadley & McCloy LLP where he co-chaired the Firm’s project finance and energy practice. Ed was identified for his work in renewable energy as one of “The Decade’s Most Influential Lawyers” by The National Law Journal, and was previously named one of the “Five Most Influential People in Renewable Energy” by Euromoney/Institutional Investor. Ed has his BA and JD from the University of California, Los Angeles.

Ben Kortlang

Partner, Kleiner Perkins Caufield & Byers

Ben is a Partner with Kleiner Perkins Caufield & Byers where he focuses on growth-stage greentech investing. Prior to KPCB, Ben worked at Goldman Sachs for eight years, most recently co-heading Goldman’s Alternative Energy Investing business. In this capacity, Ben managed Goldman’s multi-billion dollar portfolio of alternative energy investments including Horizon Wind Energy, SunEdison and First Solar. Prior to joining Goldman Sachs, Ben was an Associate with A.T. Kearney and a Business Analyst at National Australia Bank. Ben has a BS from RMIT University, a Bachelor of Commerce and an honors degree in econometrics from the University of Melbourne, and an MBA from the University of Michigan.

Joe Kraus

Partner, Google Ventures

Joe has been a Partner at Google Ventures since 2009, focusing on investments in mobile, gaming, and local services. Before moving in to Ventures, Joe held multiple product management roles at Google, including Blogger, Picasa, Sites, Friend Connect, and OpenSocial. He co-founded JotSpot in 2004, a wiki company that was acquired by Google in 2006. In 1993, Joe co-founded, an early Internet search engine.  During his tenure, he held multiple positions in the company, including leadership roles in product, business development, and marketing. In addition, Joe has been an active angel investor in multiple companies, including LinkedIn, Aardvark (sold to Google in 2010), Kongregate, and OpenCandy and he serves on the board of the Electronic Frontier Foundation (  Joe has a BA from Stanford University.

Nat Kreamer

CEO, Clean Power Finance

See above

Alex Weiss

Managing Director, ClearSky Power & Technology Fund I LLC

Alex is currently Managing Director of ClearSky Power & Technology Fund I LLC, a venture capital fund that primarily makes mid to late stage and growth equity investments in power and technology companies. He is also Vice President and Chief Investment Officer of a Fortune 200 energy company, and in this role he is responsible for investment decisions and fund management for more than $9.5 billion of invested financial assets. Previously, Alex was a vice president at Morgan Stanley, and a managing director in the investment banking divisions at Smith Barney and Paine Webber. He has over 20 years of experience working with private equity and venture capital funds. Alex has completed transactions across investment life cycles in a range of industries, including extensive experience in investing, equity raising, high yield, mergers and acquisitions, leveraged recapitalizations and restructurings. Alex holds a BA in mathematics and economics from Boston University and an MBA in finance from Columbia University.