Who We Are


We are an energetic and committed team of professionals, sharing our knowledge and experience to offer tailored energy and sustainable infrastructure concepts and solutions to our clients.



Rollie Armstrong

Group Managing Director
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As one of our Managing Directors, Rollie is focused on developing and implementing growth opportunities in the rapidly evolving market of renewable energies.

Prior to founding CRONIMET Mining Power Solutions (today O&L Nexentury), Rollie co-founded and served as a director of SOLEA Capital GmbH, an internationally active PV development, investment and transaction structuring company. Under his leadership SOLEA successfully developed, built, operated and transferred utility scale PV projects throughout Europe and South Africa.

As the responsible manager of a Munich based private equity group, Rollie profitably executed investments in the renewable energy sector. Further, Rollie spent six years with Ernst & Young Germany as a Corporate Finance and M&A Manager.

Rollie earned an MBA in Corporate Finance from Northeastern University in Boston and holds an undergraduate degree (B.Sc.) in Financial Services from UNLV, in Nevada.

Steffen Kammerer

Group Managing Director
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Besides his general management focus, our Managing Director Steffen is responsible for transaction- and project management, project financing and structuring of energy projects worldwide.

The business lawyer with degrees from the HFWU Nürtingen and the University of Economics Bratislava started his career at the international consulting company Ernst & Young in the area of mergers & acquisitions with a specialization in financial and advisory services to banks.

For an international investment company Steffen further actively led a considerable number of transactions and financing deals in the field of renewable energies.

In his previous role as Co-Founder and Director of SOLEA Capital GmbH, Steffen successfully managed the international expansion of the SOLEA group into Africa and Australia.

Bernd Walbaum

Group Managing Director
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Bernd graduated with his Master’s Degree in Business/Managerial Economics at the University of Hamburg in 1980. After working in the printing and media business as Sales and Marketing Director and Managing Director in Germany, Great Britain and USA and later as Management Consultant for Ernst & Young, he then served as Managing Director at Helion Solar, Germany and Solsquare, South Africa for five years. As from 2012, Bernd Walbaum is the Chief Executive Officer of O&L Energy and since August 2020 also Group Managing Director of O&L Nexentury GmbH.

Sabrina Steinhauser

General Manager: Corporate & Finance
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Sabrina heads our corporate team at O&L Nexentury. Committed to ensure a steady organizational development, Sabrina manages O&L Nexentury’s international subsidiaries and teams as well as the coordination of international projects.

She therefore directs the company group’s operations on a daily basis, including overseeing strategic execution in critical areas such as marketing, workforce development, project management, accounting, finance, and business administration. As a member of the board, Sabrina is involved in forward-thinking business stewardship and roadmaps.

Sabrina earned a M.A. in International Business with focus in Marketing from the University of Applied Science in Kufstein, Austria and holds a Bachelor’s degree in Economical Geography from the Ludwig-Maximilians-University in Munich.

A team of experts crafting efficient solutions


Nkosi Nkube

Executive Director Nexentury SA
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Nkosi serves as O&L Nexentury South Africa’s Executive Director. He gathered extensive experience in the sourcing and implementation of financial transactions while working for financial institutions and specialist advisory boutiques including Old Mutual Specialised Finance, Nedbank and Basis Points Capital. Prior to his directorship at O&L Nexentury, Nkosi was a co-Director at SOLEA Renewables (Pty) Ltd (SA), a subsidiary of SOLEA Capital. Nkosi has gained years on domestic development and project execution experience in the renewable energy sector and continues to drive new project development opportunities for O&L Nexentury.

As Executive Director of O&L Nexentury’s South African Team, Nkosi is responsible for the organization of the corporate management, project coordination as well as financing in our South African subsidiary.

Alex Vassev

Executive Managing Director, Head of SADC
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Alex is in charge of our team of professionals in the SADC region and further heads our Legal Department in his capacity as an English and South African-qualified lawyer.

Alex previously founded Vassev Attorneys, a boutique law firm concentrating on Private Equity, Mining and Renewables and further practiced as an M&A lawyer at White & Case LLP.

Dr. Georg Wirth

General Manager: Engineering
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As head of our technical department, Georg is responsible for the coordination of the technical feasibility studies, engineering analyses and procurement as well as for the development of hybrid PV, Diesel and energy storage system designs. Prior to joining O&L Nexentury, Georg led the photovoltaic grid integration team at the University of Applied Sciences Munich’s solar energy lab since 2010. During his four year stint, Georg managed a number of complex grid stability research projects outsourced to his lab by companies such as E.ON, General Electric, Siemens, and research institutions including the Technical University of Munich, DLR, and the Fraunhofer Institute.

Georg’s educational background started with a training at Siemens across the electrical engineering division. Georg achieved his Ph.D. Degree from the Carl von Ossietzky University at Oldenburg on modelling the meteorological effects of grid distribution physics under high photovoltaic penetration scenarios.

Luc Tanoh

Senior Project Advisor
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Bringing over 30 years of experience in the Telecom, IT, Power Utility and Engineering industries throughout Africa, US and Europe to O&L Nexentury, Luc is a highly regarded Senior Executive, GSM and Energy specialist, combining significant board-level experience with in the field regional and continental leadership roles .

As Head of West Africa, Luc is responsible for business and project development throughout West Africa and the Francophone regions of Africa. He holds a Master’s Degree of Sciences in Electrical Engineering from the Swiss Federal Institute of Technology and a Master’s Degree of Sciences in Industrial Engineering and Operations Research from the University of Berkeley in California.


Mladen Savic

Senior Financial Analyst
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Mladen is our Senior Financial Analyst and is responsible for project finance, financial modelling, project controlling and all other quantitative analyses surrounding our projects.  

Mladen earned his Bachelor’s degree in the United States at Georgia State University, in the field of Economics and Finance. He moved to Germany in 2015 to pursue his Master’s degree at the Ludwig-Maximilian University in Munich. He joined the company in 2017 as a working student, where he was first exposed to the renewable energy sector and project finance.  

He graduated from Ludwig-Maximilian University in 2018 with a Master of Science degree in the field of Economics. Mladen has since deepened his skillsets in the areas of project finance and financial modeling enabling him to grow into his current role at O&L Nexentury. 


Alexander Perstling

Junior Business Developer
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Alex is the latest member to the team in Namibia and is our Business Development Specialist, responsible for project development and corporate innovation.

Alex has a Bachelor in Business Administration (BBA) which he obtained from United International Business Schools while studying at their Milan, Amsterdam and Brussels Campus.

Johan Muller

Legal Counsel
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Johan serves as Legal Counsel of O&L Nexentury South Africa.

He has more than 20 years’ experience in the Legal, Commercial and Business environment.

After graduating from the Free State University Law School in South Africa, he gained 12 years’ experience in private legal practice before joining an international renewable energy company between 2012 and 2020 as in-house Legal Counsel.

As Legal Counsel of O&L Nexentury South Africa, Johan supports the Legal Department in project development, from business development activities to construction, commercial operation and beyond.

Lonwabo Ntshiba

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As Junior Draftsman at O&L Nexentury SA (Pty) Ltd, Lonwabo supports our technical team and assists in O&M services, yield assessments and the drawing of PV plant layouts. He holds a national diploma in Mechanical Engineering from the Cape Peninsula University of Technology and started his BTech in Mechanical Engineering at the University of South Africa. With previous trainings in Engineering at the Two Rivers Platinum Mine and the Grinaker-Ita Mining, Lonwabo has built his background in the renewable engineering and mining industry.

Mberitjiua Hange

Operations & Maintenance Engineer
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Mberitjiua is our Operations & Maintenance Engineer. He is responsible for the O&M Services of all the O&L Nexentury Solar Plants in Namibia, including day to day monitoring, supervision, controlling, maintenance coordination and optimization of the solar plant’s performance. Apart from being involved in construction, he is also responsible for configuration of communication systems and commissioning of our solar PV plants and is specialized in SMA inverters. Hange holds a Master’s Degree in Electrical Engineering from the University of Namibia and a certificate in Advanced Project Management. His career started in 2017 after graduation, when he joined the O&L Group through our Talent Attraction Program.

Shingirai Matunhira

Hybrid System Operator
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Shingirai manages the solar hybrid plant at Thabazimbi and ensures the reliable delivery of electricity to the mine. He takes care of the power grid and constantly communicates with our customer as well as with the utility provider. Supporting our engineering team, he evaluates the data of the power systems for operational and consulting purposes. Shingirai holds a Diploma in Mechatronics, Robotics and Automation Engineering from the University of South Africa.


Michelle Deville

Management Assistant (Maternity Leave)
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In her role as Management Assistant Michelle supports the management board as well as the corporate department in developing organizational structures and networks with special regards to Western Africa. She is further responsible for the marketing department.
Before joining OL NX Michelle worked in the Sales & Marketing department of an international hotel chain. She holds a Bachelor’s Degree in Hospitality Management.

Edelweiss Junius

Personal Assistant
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Personal Assistant to two Managing Directors since 2016, working alongside the executive team, with 20 year experience in commercial areas, sales and marketing, customer services and administrative support. Before joining the energy business she worked in the banking and property business.

She is a powerful force in the workplace and uses her positive attitude and tireless energy to encourage others to succeed. Edelweiss is a professional and creative leader with great communication skills to achieve goals and targets.

Anga Finini-Khumalo

Team Assistant
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As a Team Assistant Anga performs all front desk and office administrative duties and supports the team’s day to day business.  Before joining our team, she has worked at exporting as well as construction company. She holds a National Diploma in Food Technology at Cape Peninsula University of Technology and has started BTech in Management Services at University of Johannesburg.

Linja Uys

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As part of our team based in Namibia, Linja is responsible for the accounting. She further supports the corporate department in various matters. Linja graduated from Stellenbosch University South Africa with a BDram Degree and from University of South Africa in 2014 with a BCompt Degree with the focus in Auditing and Assurance. She completed her SAICA articles in 2013 at BGR De Jager Boshoff in South Africa.

Linja ended her auditing career in 2017 where her focus shifted to management accounting/cost accounting and taxation. Before joining O&L Nexentury, Linja consulted for two years to various entities and individuals.

Beaulah Gabriel

Administrative Clerk
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Beaulah serves as Administrative Clerk at OLC Energy Services (PTY) LTD, a subsidiary of O&L Nexentury in Namibia. She performs a wide variety of office support and clerical duties and activities. She supports the finance and accounting department, sales and distribution and manages the inverter warehouse.

Walking the walk in all we do