The greentech Management Board.
As a group of companies we work together collaboratively, successfully and in a value adding manner. We are led by a strong management team.
Act with foresight, manage successfully, grow together
The greentech Group is led by an experienced management board. It is formed by five managing partners.
The Management Board
Ingo Rehmann
Chief Executive Officer (CEO)
Ingo Rehmann is the head of the Management Board of the greentech Group, where he leads the company's corporate and strategic development efforts. He oversees the Central Services, which act as an internal provider of essential group-wide functions, including Accounting, Human Resources, Corporate Development, and IT Services. As CEO, Rehmann serves as the spokesperson for the group and represents greentech externally. Together with the CFO, he is also responsible for reporting to shareholders and stakeholders.
Ingo Rehmann has been active in the PV industry since 2005. He held various management positions at Conergy AG, including in the areas of M&A and as Head of Market Intelligence. In 2008, he founded greentech and developed the company into one of the largest independent PV O&M and engineering companies in Europe. He studied business administration in Germany, Australia and Spain.
Aleksis Schäfer
Chief Financial Officer (CFO)
As CFO, Aleksis Schäfer is responsible for Corporate Finance & Corporate Controlling, Corporate Accounting and Data Science. Together with the CEO, he is also responsible for reporting to shareholders and stakeholders.
Aleksis Schäfer joined greentech in 2010 and, among other things, was responsible for setting up the Asset Management division. He has been active in the PV industry since 2005, where he initially gained experience in post-merger integration at Conergy AG. In 2008, he joined the Boston Consulting Group as a management consultant. Aleksis Schäfer studied Business Administration at RWTH Aachen University and holds a Master's degree in Engineering Physics from Helsinki University of Technology.
Oliver Herzog
Chief Development Officer (CDO)
As Chief Development Officer (CDO), Oliver Herzog is responsible for the group-wide project development of photovoltaic and battery storage solutions in greentech's core markets of Germany, the UK and Italy - from project identification through to construction readiness.
Oliver Herzog studied Business Administration in Cologne. Oliver Herzog studied business administration in Cologne. In 2004, he started his career in the PV industry at Conergy AG, where he held various senior management positions. There, he most recently headed the company's project development and financing activities as Managing Director in Singapore and India until 2011. After interim positions at a consultancy specialising in renewable energies and an issuing house, he moved to Enerparc AG in 2015, where he was responsible for the external EPC business for third-party clients as Managing Director. Oliver Herzog has been a managing partner at greentech since 2020.
Felix von Buchwaldt
Chief Investment Officer (CIO)
Felix von Buchwaldt oversees the investment management, project finance, and asset management for the greentech Group as CIO. His responsibilities include the commercial management of plants in the company’s own portfolio and for external clients, as well as project execution and origination activities.
Felix von Buchwaldt studied business administration in Hamburg and has held various senior management positions in the areas of business development, project finance and asset management in the Erck Rickmers Group over the past 20 years. From 2012 to 2023, he was CEO of Nordcapital GmbH, an asset management company that financed investments totalling more than EUR 7 billion in the areas of real estate, shipping, private equity and renewable energies.
Joern Carstensen
Chief Technical Officer (CTO)
In his role, Jörn Carstensen combines the management of all technical areas of the greentech group. As CTO, he is responsible for plant construction, engineering services and technical management. The aim is to create uniform standards and processes across all technical areas at greentech, thereby ensuring company-wide synergies, high quality and the greatest possible transparency.
Jörn Carstensen joined greentech in 2014 as Business Development Manager. In addition to developing various European markets, he built up the Engineering and Technical Advisory division. From 2006 to 2014, he worked for the Conergy Group in various international corporate and business development positions. Prior to that, he worked for a consulting unit of Accenture and supported utility companies in strategic and organisational issues. Jörn Carstensen holds a degree in Industrial Engineering with a specialisation in Energy and Environmental Management from the Universities of Flensburg and Southampton.