Isekai 1

20249 Hamburg 

T: +49 (0) 40 3989 59-10
E: info (at)




Fahrenhorster Weg 55
22889 Tangstedt 

E: info (at)

Christoph Portrait.jpg

Christoph Schmitt
Managing Director solar-konzept GmbH
Managing Director solar-konzept International 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.

Karen Kedziora
Managing Director solar-konzept 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.

Jörg Brunner

Managing Director solar-konzept Entwicklungs 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 Entwicklungs GmbH and was appointed managing director in September 2020.

Stephan Schmitt

Project Development solar-konzept Entwicklungs GmbH


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 Entwicklungs GmbH as a project developer.

Dr. Guido Terwey

Regionalleitung Deutschland Mitte/West


After studying landscape planning and part-time studies in applied geoinformatics as well as a doctorate at the Technical University of Kaiserslautern, Dr. Guido Terwey worked until 2014 as project manager and team leader for open land photovoltaics Germany at juwi solar GmbH. Among other things, he was responsible for the project development and realisation of the Georgsdorf solar park, the largest solar park in Lower Saxony with an installed capacity of 25 MWp and an area of 60 ha in 2011.


Subsequently, Guido Terwey worked at Prowind GmbH in Osnabrück as Head of Project and Project Development for Wind Energy Projects. Finally, he was responsible for the development of the photovoltaic open spaces business segment at Prowind Solar Gmbh.


In March 2021, he joined solar-konzept Entwicklungs GmbH, where he is in charge of the German Central/West region from the Bad Bentheim site in southern Lower Saxony on the border with North Rhine-Westphalia.



Isekai 1
20249 Hamburg 

T: +49 (0)40 3989 59-10

E: info (at)

c.schmitt (at)

Nikolaus von Einem

Managing Director solar-konzept International

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.

Birgit Eggl

Managing Director TPSolar-Konzept
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-konzept as of January 2017.

Martin Voigt
Managing Director TPSolar-Konzept
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-konzept as of January 2017.


Galleria Vintler 17
39100 Bolzano

T: +39 (0) 340 919 61-55
E: inf
o (at)


Andrea Cristini
Managing Director solar-konzept Italia srl

Andrea Cristini graduated in mechanical engineering and gathered an eleven years expertise in project development of national and international renewable energy projects.

For over 12 years he performed as a Managing Director and Country Manager, responsible for the international project development in Italy and EPC business.


For the past six years he has been a Managing Partner in Italy responsible for 10 projects with 40 million of sales before he joined solar-konzept for the Italian market. 




47 Vouliagmenis Avenue, Eliniko

16777 Athens



T: +30 2102 200 951
E: g.tzanidis (at)

Solar-konzept photo_bearbeitet.jpg

George Tzanidis

Managing Director solar-konzept Greece

Following his studies in mechanical engineering from City University in London and a master’s degree in business administration from Leicester University, George Tzanidis started his professional career in 2001 with EDF Energy as a derivatives trader. In 2004 he joined BP as a member of the commercial and retail management team. In 2008 George decided to enter the field of renewables with BP Solar. 


Following his departure from BP in 2010 he worked for three international energy companies, SunEdison, Conergy and Hanergy overseeing project development activities and the implementation of commercial strategies in the region of South East Europe. He is a shareholder and manager of solar-konzept Greece as of March 2018. 

Our JV partners in the Netherlands


TPSolar B.V.

TPSolar-Konzept B.V.


Melbournestraat 9
1175 RM Lijnden



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

E: info (at)


Erik Wieffer

Managing Director / Managing Director TPSolar BV   

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 concept. 

Rene Hendriks

Managing Director / Managing Director TPSolar BV   

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-Konzept since January 2017.