ENSPEC POWER: Power Quality, Grid Code, Global Growth – Enspec Energetic on Opportunities

When Mara and Tim Rastall completed a management buyout of Enspec Power in 2023, they took the reins of a company already known across the energy sector for its unmatched technical expertise and unwavering focus on power quality. Founded in 1999, Enspec had built its name as a trusted electrical engineering firm specialising in power quality and grid connection — two areas now at the heart of the global energy transition. Under new leadership, the company is entering a new phase of expansion, leveraging its hard-earned reputation and a rapidly growing team to serve clients across the world.

“We were established in 1999 but we completed the MBO in 2023,” CEO Mara Rastall tells Energy Focus. “We are an electrical engineering firm that specialises in power quality and grid connection. 80% of our core clients are large energy developers including wind farms, solar farms, hydro plants, BESS systems etc.”

From its headquarters in the UK, Enspec Power works with developers and asset owners across a wide range of renewable energy technologies, helping projects overcome one of the most complex challenges in the clean energy value chain: connecting to the grid.

GRID CONNECTION EXPERTS

Securing a grid connection agreement is one of the biggest hurdles for renewable developers today. Enspec’s niche expertise sits at the point where engineering meets compliance, helping developers prove that their sites meet grid code standards through advanced power system studies, simulations, and equipment design.

“Our consultancy service has a specialist team of senior power system engineers,” says Rastall. “They run studies and simulations to show whether or not a site does meet grid code compliance. If it does – great; our report is submitted along with the rest of the reports needed for the grid connection agreement. If it doesn’t, we design, manufacture and commission mitigating solutions such as harmonic filters, reactive compensation units, point-on-wave switching and other hardware solutions that sit on substations to solve the issue so that the site meets the power quality regulations and can obtain that grid connection agreement.”

This expertise has positioned Enspec as a key enabler in some of the UK’s most ambitious renewable energy projects. Its work on ScottishPower Renewables’ Viking Wind Farm in Shetland — one of the most powerful onshore wind projects ever developed in the UK — exemplifies how Enspec’s technical understanding can overcome challenging conditions at weak grid points. As Rastall notes: “It was highly publicised as an excellent example of a very powerful onshore windfarm connecting at a really weak grid point and the types of considerations that had to go into that.”

Beyond consultancy, Enspec’s engineering and manufacturing teams design bespoke power quality solutions. The company is renowned for its 33kV passive harmonic filters — an increasingly critical technology as renewable penetration and non-linear loads increase across transmission and distribution networks.

“33kV passive harmonic filters is what we are known for, and we continue to get booking after booking,” says Rastall. “Our Director of Consulting, Kerim Ozer, submitted a paper this year about harmonic filter design and the downward roll towards a potential problem for the grid based on different sites have misaligned harmonic filters on site. The paper has been picked up by four international symposiums this year showing that it is in fact a really key topic.”

KNOWLEDGE PARTNER

Rastall describes Enspec as a ‘knowledge partner’ — a term that encapsulates the company’s approach to client relationships. Rather than acting as a supplier or a consultant alone, Enspec embeds deep technical insight into every project, ensuring clients are not just compliant, but optimised for long-term performance, and, as much as possible, understanding of technical details.

“Fundamentally, we know that the green energy transition is not currently 100% possible because of the technical challenges. There are not many challenges that we are not able to solve. We are a big enough business and we can handle multimillion Pound projects, but we are a small enough business to ensure that all of those projects have senior technical leaders on them.”

This combination of size and specialisation gives Enspec a unique agility in the market. The company can mobilise its senior engineering talent across large, complex projects while maintaining the responsiveness of a boutique firm. Rastall points to the practical experience of her engineers as one of the company’s strongest differentiators. “We have seen examples of projects where a 33kV harmonic filter has been advised but is actually not at all suitable and a 400kV filter is required. That can be a horror story in the industry because of the dramatic budget and space differences. At that point, you may not have the space.”

By combining 25 years of field experience with cutting-edge analysis and design, Enspec ensures that each solution is technically sound, economically viable, and tailored to its client’s needs. “We leverage 25 years of insight into finding the best and most economical solutions for our clients and explain it on their terms,” she adds.

INNOVATION AND EXPERTISE

Enspec’s technical depth is reflected in its multidisciplinary service model. The company operates across consultancy, engineering, manufacturing, and site services — providing clients with complete, end-to-end expertise from feasibility studies through to commissioning and ongoing maintenance. This integrated approach ensures that every aspect of a project’s electrical system, from design to operation, meets the highest standards of performance and reliability.

“We also commission and maintain all of our own equipment through our site services division,” says Rastall. “20% of our client base is large energy users including data centres, hospitals, zoos, advanced manufacturing sites… anything that draws a lot of power.”

As large energy users face mounting challenges related to power quality, voltage stability, and harmonic distortion, Enspec’s engineers are called upon to diagnose, repair, and optimise complex systems. Director of Site Services, Tony Cook, underlines the importance of continuous monitoring and preventative maintenance to avoid costly disruptions: “Proactive maintenance allows for early detection of potential issues before they become significant problems. By scheduling regular inspections and testing, clients can prevent failures that might otherwise lead to costly repairs or operational interruptions.”

This proactive philosophy defines the Site Services division — a team trusted not just for its ability to commission new systems, but to keep them running at peak efficiency. For critical energy users, that reliability can make the difference between seamless operation and costly downtime. As Rastall puts it: “Our Site Services can recommend the best type of equipment in order to repair and mitigate.”

Recognising the growing complexity of client demands, Enspec has also established a new engineering department focused on innovation and bespoke development. “We have created a new engineering department in the last year,” says Rastall. “This came about because we were getting an increasing number of enquiries for services and the development of products that sit outside our regular offerings. Simply, when someone needs something that doesn’t exist, we put engineers on the problem to figure something out.”

That agility and problem-solving ethos have been instrumental in Enspec’s rapid growth. Rastall herself joined the business during the Covid period to help expand the consultancy division — and what followed was remarkable. “The department grew by 400% in six months,” she recalls.

“We were growing quickly and started to focus on operational challenges, including recruitment as there is a skills shortage in our industry. We went through the MBO which took around 18 months but we more than doubled the team. I became the CEO and we now have a team of 40 people – all brilliant minds – and we are looking to add more people in the coming months.”

GLOBAL GROWTH

While Enspec remains rooted in the UK, its ambitions are global. The company has already incorporated a US entity and completed a large project there, marking the first step in a wider international strategy. “The USA has been on our agenda for the last few years and we have aspirations from a renewable generation perspective.”

The company is also eyeing opportunities in the Asia Pacific region, where the pace of renewable integration mirrors the UK’s early grid transformation. “Asian Pacific Islands are key target markets,” Rastall confirms. “We recently took part in a trade mission to Japan and the conversations were very enlightening… If you look at Japan and Taiwan, they have very big offshore wind goals that will connect to the grid. They are very open about not having inhouse expertise to solve those challenges.”

With deep experience connecting renewables in weak grid environments — as demonstrated at Viking Wind Farm — Enspec is well placed to transfer its knowledge to emerging renewable markets. “Fundamentally, these are challenges that we have seen a lot of,” Rastall adds.

Looking ahead, Enspec is also exploring the fast-developing hydrogen market, where grid interaction and electrolyser behaviour present new technical frontiers. “Hydrogen in general is an opportunity,” she says.

“We are taking a forward step so that we have an understanding of the landscape… Excitingly, we already have live projects that we are working on in the UK and US markets.”

ENGINEERING TOMORROW

For Enspec Power, the next chapter is about scale — not just in size, but in influence. From harmonics to hydrogen, from the UK to Asia Pacific, the company continues to apply its core strength: turning technical complexity into clarity.

“This industry is like a glitter explosion of opportunity,” says Rastall. “You have to sift through to find out what to go for first.”

As the global energy transition accelerates, Enspec Power’s combination of deep technical expertise, proven hardware solutions, and leadership grounded in real-world engineering positions it as a crucial partner in connecting the clean energy future.