About us
Who we are
The name SONNWINN comes from Old High German: “sunn” (sun) and “wini” (friend) — literally “friend of the sun”. With this name we underline our commitment to the energy transition.
As the hub of a network of experts, SONNWINN GmbH supports you in every question concerning photovoltaics and electricity storage. With expertise, enthusiasm and an open ear we accompany you at each step — from the first idea to implementation.
Our advice is individual, solution-oriented and based on the current state of technology, science and engineering. We meet you as equals — straightforward, comprehensible and as partners.
Whether trackers, agri-PV, floating PV or large-scale storage — we are at your side on every technical question with independent advice and well-founded (special) assessments.
Your advantage: one point of contact for a broad portfolio of services.
Selected references
Status: August 2026
Of these, 655 assessments and more than 50 assignments have been delivered by SONNWINN GmbH since its incorporation in May 2025.
Technical inspections
The technical inspections were carried out on ground-mounted systems (750 kWp to 50 MWp) and roof-top systems (5 kWp to 13 MWp). These include
- Technical due diligence
- Construction progress checks and inspection of the construction work
- Evaluation of quality assurance measures
- Technical inspections after commissioning
- Inspections at the end of the warranty period
- Recurring inspections
- Characteristic curve and infrared measurements
The inspected PV systems are located in Germany, Denmark, France, Italy, the UK, the Netherlands, Kazakhstan and Hungary.
In total, systems with an installed capacity of 1.2 GWp were inspected.
Expert opinions
The assessed PV systems were planned or installed in Germany, Turkey, Egypt, the UK, Romania, Slovenia, Pakistan, Jordan, Chile, the Philippines, Belarus, Mongolia and Ukraine. Activities included
- Preparation of yield reports
- Defect assessments
- Preparation of irradiation data from various sources
- Simulation of the PV system with PVsyst
- Presentation of the forecast results in a report
- Evaluation of yield forecasts from other experts
- Glare assessment
The management
Dipl.-Ing. (FH) Marco Wilke
Managing Director / Expert for photovoltaics and storage
Marco Wilke is an engineering physicist and has been working as an expert in the field of photovoltaics since 2011. After several years in employment, he has worked independently since 2015. He specialises in construction progress inspections and technical inspections of rooftop and ground-mounted systems as well as storage systems and yield assessments based on PVsyst. In addition to PV systems in Germany and Europe, he has also assessed systems in non-European countries.
Certificates
Dipl.-Ing. (FH) Robert Pfatischer
Managing Director / Expert for photovoltaics and storage
Electrical engineer Robert Pfatischer was already involved in the remote monitoring of selected systems in Germany’s “1,000 Roofs Programme” during the 1990s. He gained many years of experience as Head of Quality Services at meteocontrol GmbH, where he was co-founder, authorised signatory and managing director from 1998 to 2020. In this context, he was involved in many projects in Germany and various European markets. He has also been realising and operating his own PV systems for many years. He continues to focus on the quality assurance of projects in an increasingly challenging environment.
Further experts
Dr.-Ing. Stefan Bofinger
Co-Founder / Expert for photovoltaics
Stefan Bofinger has been working as an expert in the field of photovoltaics since 2002. As an independent consultant, he supports investors and banks with photovoltaic project developments. Stefan Bofinger studied electrical engineering and completed his doctorate on “Energy supply grids with a high proportion of photovoltaic solar energy: location assessment, solar power forecasting, grid integration”.
Mathias Röper, M. Eng.
Co-Founder / Expert for photovoltaics
Mathias Röper studied Environmental Engineering (B. Sc.) and Renewable Energy Systems (M. Eng.). He has been working as an engineer and expert in the field of photovoltaics since 2017. His core areas of expertise include glare reports and preliminary planning (technical system layouts) for PV systems. He also prepares special reports such as detailed ground shading analyses.
Dipl.-Ing. (FH) Christian Binder
Expert / Technical Programme Management for Energy Management Systems
Christian Binder has 24 years’ experience in software engineering at a market-leading manufacturer. He is the founder of SENERGY365.DE. He specialises in expert reports, consulting, analysis and commissioning of energy management systems.
Arthur Zlotver
Solar glare assessment expert
Felix Worm
Back office
Emilia Heinzel
Geographic information systems
Cedric Wilke
Yield reports
Adrian Pfatischer
Data preparation and preliminary planning
Steen Oppermann
Yield reports
Ani Ostatishvili
Marketing and design / system visualisations
Lukas Schramm
Solar glare consultant