Isekai 1

20249 Hamburg 

T: +49 (0) 40 3989 59-11
E: info (at)

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Christoph Schmitt
Managing Director solar-konzept GmbH

Christoph Schmitt studied industrial engineering at the Nordakademie in Elmshorn. From 1999 to 2006 he built up the Major Projects division at BP Solar, one of the world’s largest solar energy companies.

From 2006 to the beginning of 2009 he was responsible for project development in the photovoltaic sector at Epuron GmbH, and ubsequently at Conergy AG. In May 2009 he joined solar-konzept gmbh as Managing Director.


Jörg Brunner

Managing Director solar-konzept GmbH

After studying forestry in Göttingen, Jörg Brunner was head of land management and land acquisition at P&P Dienstleistungs GmbH & Co. KG until 2013, responsible for the service and project development of short rotation plantations (SRC) and reforestation projects in Germany.


Subsequently, Jörg Brunner worked as a project manager for wind energy projects in Bavaria, Baden-Württemberg, Thuringia and Saxony at ABO Wind AG until 2019.


In September 2019 he switched to project development manager at solar-konzept GmbH and was appointed managing director in September 2020.

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Stephan Schmitt

Regional Management Germany north

After studying geography and history, Stephan Schmitt led a local management office from 2009 to 2012 with a main focus on regional economic development.


From 2012 to 2019 he carried out as a project numerous commercial film productions for regional and national positioned companies. In 2019 it changed to solar-konzept GmbH as a project developer.


Dr. Guido Terwey

Regional Management Germany center/west


After studying landscape planning and geoinformatics as well as completing his doctorate at the Technical University of Kaiserslautern, Dr. Guido Terwey worked as a team leader for open space photovoltaics at juwi solar GmbH until 2014.


He then worked at Prowind in Osnabrück as head of department for wind energy projects and the development of the field of photovoltaic open spaces.


Since March 2021, he has been in charge of the Central / West Germany region at solar-konzept GmbH from the Bad Bentheim location in southern Lower Saxony on the border with North Rhine-Westphalia.


Susanne Kleinert

Location scout and geodata analyst

solar-konzept GmbH

After studying geoecology at the University of Tübingen, geodata accompanied her professional career. First in the areas of flood risk management and hydropower potential in Baden-Württemberg (Büro am Fluss GmbH) and then in the course of taking care of environmental monitoring at Frankfurt Airport for the State of Hesse (environmental and neighborhood house).

Since November 2020 she has been responsible for the search for suitable locations for photovoltaic projects as well as the analysis of geodata at solar-konzept GmbH and supports project development.


Sascha Kopietz
Head of Technology and Construction
solar-konzept GmbH

After completing his professional training as an electrical installer and further training as a state-certified technician, Sascha Kopietz worked for Solar Engineering Decker & Mack GmbH as a specialist planner and site manager for the implementation of ground-mounted PV systems until 2015.


Sascha Kopietz then worked from 2016 to 2021 at e4r-engineers for renewables GmbH in Berlin as project and construction manager for the construction of PV systems in Germany and the Netherlands.


With more than 10 years of experience in the PV sector, he moved to solar-konzept GmbH in June 2021 and is in charge of the technical planning and implementation of the projects.


Nikolaus von Einem

Shareholder solar-konzept GmbH

Nikolaus von Einem studied environmental sciences at the Swiss Federal Institute of Technology in Zurich. Since 2005 he has developed photovoltaic projects for various companies. 

In 2007 he established and was head of EPURON Italia,
responsiblefor the project business of the Conergy group in Italy. In 2008 he took over the management of solar-konzept italia srl.

Our JV partners in the Netherlands


TPSolar Nederland B.V.


Melbournestraat 9
1175 RM Lijnden



T: +49 (0)40 3989 59-12

E: info (at)


Erik Wieffer

Managing Director / Managing Director TPSolar Nederland B.V.   

Erik Wieffer studied sales and marketing in Amsterdam and worked from 1991 to 2000 for various Dutch manufacturers of metal products and drinking water installations.

From 2000 to 2010 he was senior manager for CRH PLC (BIK Bouwprodukten BV) and Saint Gobain Glass Solutions in the areas of roof installations and construction glass. Since 2010 Erik Wieffer works in the solar glass industry and the solar industry in the Netherlands.


In 2015 he founded TPSolar BV with Rene Hendriks. From January 2017, he is a shareholder and managing director of TPSolar Nederland B.V.. 

Rene Hendriks

Managing Director / Managing Director TPSolar Nederland B.V.

After studying economics at the Vrije Universiteit Amsterdam Rene Hendriks worked for Saint-Gobain from 1991 to 2005. He started at Isover SGG and after 4 years joined Saint-Gobain Glass. Before moving from SGG to a medium-sized glass company in 2005, he held various management positions and started selling solar glass in 2006. This gave him a valuable insight into the solar industry.


He successfully sold solar glass throughout Europe to solar panel manufacturers and gained extensive experience in project sales and project development in Germany and abroad. He founded TPSolar together with Erik Wieffer at the end of 2015 and has been a partner and managing director of TPSolar Nederland B.V. since January 2017.


Birgit Eggl

Managing Director TPSolar Nederland B.V.
Partner solar-konzept International GmbH

After completing a master's degree in environmental sciences and working at a consultancy for finance and investment in renewable energies for a couple of years, Birgit Eggl was employed by the Hamburg-based solar company Conergy for 8 years. Since 2013 she has been responsible for the UK market from the Milton Keynes branch and has implemented a pipeline with over 350 MWp with her team.

Since mid 2015 she lead all project development activities and the EPC business in the EMEA region, with a focus on Europe. As part of the solar-konzept group, she is now responsible for the Dutch project business together with Martin Voigt. She is a shareholder and manager of TPSolar Nederland B.V. as of January 2017.


Martin Voigt
Managing Director TPSolar Nederland B.V.
Partner solar-konzept International GmbH

After studying industrial engineering at Jena University of Applied Sciences, Martin Voigt worked for the Conergy Group from 2005 to 2010 in the national and international large-scale projects. In 2011, he became self-employed and supported various companies in the realization of large-scale projects and in the development and evaluation of new business models. From 2012 to 2015 Martin Voigt, a managing partner with Grünstromwerk, built a new energy supplier, which was integrated into the Naturstrom Group in 2015.


In 2016 Martin Voigt worked briefly for the Aquila Group and joined solar-konzept gmbh in September, now responsible for the Dutch project business together with Birgit Eggl. He is a shareholder and manager of TPSolar Nederland B.V. as of January 2017.





Fahrenhorster Weg 55
22889 Tangstedt 


Karen Kedziora
Managing Director partenum solar GmbH

After practical training as an assistant tax advisor and studies in Mathematics and Physics at the Free University of Berlin and the University of Hamburg, Karen Kedziora joined solar-konzept GmbH in 2004. In 2006 she was appointed Managing Director.