Key TNEI contacts

Nilanga Jayawarna

Resources and Operations Director

Nilanga is the Resources and Operations Director of TNEI Services Ltd. She is an Electrical Engineer who is based in our Manchester office and has a broad range of experience in people and project management, power system studies and grid code compliance.

Nilanga gained her BSc (Hons) in Engineering from University of Moratuwa in Sri Lanka and her PhD from University of Manchester. She worked as a Post-Doctoral Research Associate at University of Manchester for four years before joining TNEI.

She joined TNEI in 2009 as a Technical Consultant and took the Operations Manager role in 2014 leading to being appointed as the Operations Director in 2016. She enjoys the daily operational challenges of leading a team of 50+ consultants whilst still being involved in the varied technically challenging projects as a project director. Nilanga has 17 years of experience in the power industry including the time she spent on her PhD on Microgrids. At TNEI she has been predominantly working on onshore renewable projects. Nilanga is the main contact for recruitment, staff training and development and operations management at TNEI.

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Nigel Tate


Nigel has been with TNEI since it’s inception and has been a constant member of the management team which has seen TNEI transform from a fledgling renewables operation in the north east of England to the multi-site, thriving and diverse specialist consultancy that it is today. He is delighted to be leading such a talented team of specialists and experts in their fields. 

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James Mackay

Director of Site Services

James is the Director of the Site Services team, which provides a range of services including noise assessment, GIS / CAD mapping, shadow flicker assessments and soil resistivity measurements.

Since joining TNEI in 2006, James has developed a particularly detailed knowledge of wind farm noise assessments and has worked on over 4 GW of onshore wind projects from initial site finding and feasibility assessment through to post construction compliance monitoring and complaints investigation. In 2013/2014 James was involved in the drafting of Good Practice Guidance for wind farm noise assessment for the Institute of Acoustics (IOA GPG).

The Site Services team has provided expert witness services in relation to wind farm noise at over 30 Public Inquiries and wider technical support for projects in the renewable energy, transmission and distribution, oil and gas, residential and industrial sectors.

James is the main contact for noise assessments, expert witness services, GIS / CAD mapping, soil resistivity measurements and shadow flicker assessments.

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James Hollender

Director of Developer Support

James heads up the Developer Support team which provides clients with the advice and support needed to take their project from conception through to construction. Skills within the team include Environmental expertise, Planning, EIA coordination, GIS, Grid Connections, Electrical engineering, Civil Engineering and Health and Safety advice.

James is a Chartered Civil Engineer and Certified Member of the APS, with extensive experience in the energy sector. His career started in the energy sector in 2004 delivering civil, structural designs and geotechnical investigations for onshore wind projects, as well as acting as Owner’s Engineer and Bank’s Engineer. James later managed a dedicated design team providing input into EIAs, discharging planning conditions, preparing detailed designs, site verifications and defective works investigations. James’ work included the repowering of 2 UK wind projects, technical due diligence across several countries and assisting a Transmission and Distribution contractor develop their Balance of Plant offering to the UK wind market.

In 2014 James joined TNEI where he has applied his skills to support developers on a range of energy projects including onshore and offshore wind, solar, battery storage, STOR, hydrogen, EVs and electricity transmission.

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Mustafa Kayikci

Director of Connections

Director of Connections, Mustafa has been with TNEI since 2007 and specialises in the modelling of power system equipment and network analysis. He has experience in load flow, fault level, harmonic analysis, traction networks, dynamic models, and the transient behaviour of transmission and distribution systems. Mustafa is the main contact for power systems design and studies, engineering design, offshore renewables, protection studies and power generation services.


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Stephanie Hay

Director of Networks & Innovation

Stephanie is Director of the Networks & Innovation Team at TNEI. She is a Chartered electrical engineer with 12 years of experience in the power industry, including a 4-year PhD on active network management and control of distribution networks and 8 years as a power system consultant.

Her experience spans power system planning, design and operation, with expertise in modelling and performing system studies. In her 5 years at TNEI, Stephanie has been supporting clients through the energy transition, providing technical and market advice on emerging technologies and delivering concept, innovation and strategy projects for utilities and other industry organisations. She recently delivered the “Black Start from Non-Traditional Generation Technologies” NIA project to National Grid ESO, and is actively involved in the Distributed ReStart NIC project, where TNEI is a project partner. Stephanie drives the development of the work of the N&I team, such that TNEI are well-placed to support the ambitions of the energy industry. She is the main contact for companies wishing to discuss innovation, strategy, regulation, network design and modelling solutions.

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Dieter Gütschow

Director of Client Strategy and Policy

Dieter joined TNEI in 2018 and has more than 20 years of electrical engineering-, international project management- and consulting experience in various areas of the electrical industry. He is passionate about making energy systems smarter and cleaner.

He has led several technical and management assignments in Africa and Europe including the development of operational strategies, policies and standards, network planning and substation design, telecommunications and SCADA systems, smart grid innovation projects, techno-economic feasibility modelling and due diligence studies.

Dieter worked as a project and programme manager overseeing the design, engineering and construction of 400kV to 33kV electrical balance-of-plant for wind farms. He has also led TNEI’s contribution on the Distributed ReStart project - a UK innovation project exploring the use of Distributed Energy Resources for black.

Dieter is the main contact for companies looking to discuss collaboration on large projects and strategic partnerships.

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Johan Smith

TNEI Africa Lead

Johan Smith is a senior consultant with over 10 years of experience in power systems analysis. His experience includes transmission and distribution system modelling, network planning and feasibility of integrating power plants into electrical grids, HVAC/HVDC interconnections and grid code compliance. During his career Johan has developed system models for electrical power networks both in Africa and internationally.

Since 2012, he has been performing steady state and dynamic grid integration and compliance studies for independent power producer renewable energy projects. His experience includes interconnected systems as well as mini grids and the influence of Variable Renewable technologies. He holds a M.Tech degree in Electrical Engineering and is professionally registered with the Engineering Council of South Africa.

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