Renewables are winning but is the grid ready?

Renewables are winning but is the grid ready?

The UK has secured record levels of solar and wind capacity as part of its 2030 renewable energy strategy. Generation is accelerating rapidly, but grid infrastructure is not expanding at the same pace. Without the right engineering solutions, renewable ambition risks outstripping operational stability.

RECORD GROWTH, GROWING CONSTRAINTS

The latest Contracts for Difference auction awarded 4.9 GW of solar and 1.3 GW of onshore wind and tidal capacity, enough to power around 16 million homes.

It’s major progress. Yet as Giles Dickson, CEO of WindEurope, has warned, you cannot have more renewable electricity without more grids.

In the UK and Ireland, limited infrastructure led to an estimated 10 TWh of renewable electricity being curtailed in 2025, enough to supply one million homes for a year. Clean power was generated but could not be transmitted, resulting in financial losses and avoidable emissions.

THE VARIABILITY CHALLENGE

Wind and solar output shifts with the weather, sometimes minute by minute. These rapid changes can cause voltage fluctuations, equipment stress and curtailment if not carefully controlled.

While renewables are now cheaper than building new gas-fired stations, cost competitiveness does not guarantee system stability. Without appropriate protection and flexibility, networks face rising strain and increasing operational costs.

A GRID WITH LESS NATURAL INERTIA

As thermal power stations retire, the system is losing the inertia once provided by large rotating machines. Inverter-based renewable generation responds faster but provides less natural damping during disturbances.

This makes networks more sensitive to voltage fluctuations and fault conditions. The transition is not just about replacing generation; it requires reengineering how the grid behaves under stress.

 CONTROLLED FAULT MANAGEMENT

In inverter-dominated systems, fault currents are less predictable and influenced by control settings and asset distribution. Traditional protection schemes may not respond reliably under these new conditions.

When ground faults occur, uncontrolled current can damage transformers, cables and switchgear, potentially causing cascading failures. Protection strategies must evolve alongside renewable integration.

THE ROLE OF NEUTRAL EARTHING RESISTORS

Neutral earthing resistors (NERs) limit fault current to a safe and predetermined level. This reduces thermal and mechanical stress on equipment and allows protection systems to isolate faults quickly and effectively.

The result is fewer unexpected outages, lower repair costs and improved resilience across renewable and grid-side infrastructure.

FROM INSTALLED CAPACITY TO DEPENDABLE SUPPLY

The latest auction results are encouraging. However, long-term success depends not only on how much renewable capacity is installed, but on how reliably it operates within a changing network.

As renewable integration accelerates, collaboration between developers, network operators and specialist engineering partners will be essential to ensure clean energy growth delivers secure and stable electricity.

To find out more about strengthening renewable networks with effective resistor solutions, speak to the Cressall team.

Lessons from COP30

Lessons from COP30

The critical role of grid stability in the energy transition

‘We can choose to lead, or be led to ruin,’ declared UN Secretary-General António Guterres, addressing delegates at COP30 in the rainforest city of Belém, Brazil. As the world pushes to triple renewable power capacity by 2030, attention is shifting from adding generation to preparing grids for the change. In light of COP30, Mike Torbitt, managing director of resistor manufacturer Cressall Resistors, examines the growing pressure on electricity networks and the role of grid stability technology as renewable deployment accelerates.

The world has recently seen record growth in renewable energy, with solar and wind forming the backbone of global decarbonisation efforts. Yet, despite that, COP30 delivered a clear message: the pace must quicken if we are to meet targets for 2030. Analysis from the Climate Action Tracker coalition, released at COP30, shows that “sticking to key climate pledges — tripling renewable energy, doubling energy efficiency and cutting methane emissions — could avoid nearly 1°C of global heating and significantly slow the rate of warming this century.”

Expanding renewable capacity at the pace needed to meet climate goals will demand unprecedented investment, infrastructure expansion and system upgrades. But increasing generation alone won’t be enough — the real challenge lies in ensuring that grids can handle the variable, fast-responding energy these new sources provide. Integrating that power reliably into networks that were not designed for variable energy sources is becoming the defining task of the energy transition.

The grid challenge behind rapid renewable growth

Renewable growth is radically changing the way in which electricity systems function. Solar and wind generation follow weather patterns, leading to steep rises and falls in generation that must be balanced in real time. As installations expand, these variations become more extreme, placing new stresses on equipment and system operators alike.

Today’s renewable output is constrained by congestion and capacity limits in transmission and distribution systems, limiting how efficiently the power is delivered to consumers. Storage capacity is expanding but remains far below what is required to balance supply and demand across all regions.

Without the right stability and protection technologies, high-renewable grids risk greater levels of curtailment, decreased asset lifetimes and reduced system reliability. As inverter-based generation becomes the dominant form of new capacity, networks are also losing the inherent stability once provided by conventional rotating machines. This shift makes grids more sensitive to faults, fluctuations and power disturbances, increasing the importance of technologies that can absorb, dissipate or smooth unexpected energy spikes.

Technology that makes high-renewable grids possible

This is where resistor technology becomes essential to keeping systems stable. Dynamic braking resistors (DBRs) offer a proven method for managing rapid changes in power flow, especially in systems where renewable output can increase or decrease quickly. By safely converting excess energy into heat, DBRs prevent over speeding in rotating equipment or instability in inverter-driven systems.

For wind turbines, DBRs are essential to managing sudden gusts or rapid changes in mechanical load. For solar, they support stability during cloud transients or fast inverter cycling and in storage and hybrid systems, they help maintain smooth operation during transitions or when switching between energy sources. At commissioning stage, DBRs also support system testing to ensure equipment performs safely before going live.

Cressall has decades of experience across renewable generation, grid infrastructure and transport applications, supplying DBRs engineered for long-term reliability, safety and demanding environmental conditions. As grids continue to evolve, this technology will continue to support the safe integration of new renewable capacity, especially in a future where inverter-based systems take on an increasingly large share of total generation.

What COP30 signals for the future

One of the key messages emerging from COP30 is that renewable growth must be matched by investment in modern, stable and flexible grids. The International Renewable Agency’s (IRENA) analysis reinforces this point, stating that “power system infrastructure and flexibility must expand at a much faster rate to accommodate rising shares of variable renewables”.

According to IRENA, at COP30 the Utilities for Net Zero Alliance (UNEZA) announced investment plans totalling over USD 1 trillion by 2030, with a significant emphasis on strengthening power grids and networks. This commitment from the world’s leading utilities demonstrates the scale of infrastructure transformation needed to support renewable expansion.

This has significant implications for grid operators, developers and technology suppliers. As renewables are installed more rapidly, system stress will rise and there will be greater need for proven solutions that ensure stability.

Digitalisation will play a growing role in improving forecasting and control, but physical safeguards such as DBRs will still be essential for protecting equipment and maintaining reliability.

COP30 reinforced the scale of work required to reach renewable and climate goals. But that transition cannot succeed unless grids can cope with the new realities created by variable, fast-responding, decentralised generation. Dynamic braking resistors offer a crucial layer of protection and stability, enabling renewable energy sources to be integrated in a secure and reliable way.

To find out more about the role of resistors in renewable energy generation, speak to Cressall’s experts

CRE733

The resistance to renewables

The resistance to renewables

Why are energy providers abandoning net-zero strategies?

Oil and gas giant BP recently walked back the net-zero targets it introduced in 2020, saying the company had moved ‘too far, too fast’. The announcement is part of a worrying trend of energy providers and other multinationals reducing or watering down their sustainability strategies. Here, Mike Torbitt, managing director of Cressall, explores the causes behind this movement and explains the role that resistor technology can play in meeting sustainability targets.

In February 2025, BP announced plans to cut its budget for renewable projects by $5 billion, while simultaneously increasing its investment in fossil fuels to $10 billion per year.

The decision will see the oil giant produce 2.4 million barrels of oil per day by 2030. Given that just 36 fossil fuel companies are responsible for over half of the planet’s emissions, this step backwards has a hugely damaging potential.

But BP is not the only energy provider to backtrack on its sustainability commitments. The move comes a year after fellow oil giant Shell dialled back its 2030 target to cut net carbon intensity from 2016 levels, lowering its goal from 20 per cent to a range of 15 to 20 per cent. But why are energy providers turning their backs on these objectives?

Profit versus planet

Currently, renewable energy projects such as wind and solar are simply not returning as much profit for oil and gas companies as fossil fuels. According to 2023 figures from NPR, US companies producing oil and gas could expect to make a return of between 20 and 50 per cent return on investment on the capital invested into projects. For solar and wind projects, the estimated figure stands at just five to ten per cent.

Consequently, there is less investor interest in the stocks of oil companies that are diverting their budgets towards wind and solar. Take for example the five-year period between the end of 2019 and the end of 2024. New York Times data shows that BP’s stock prices fell by 19 per cent and Shell’s grew by around 15 per cent. Meanwhile, the stock price of competitor Exxon Mobil, which did not invest in wind and solar energy, grew by over 70 per cent.

There are a few major barriers to profitability. The first is that oil companies may lack the sector-specific experience required in order to succeed with wind and solar projects.

Exxon Mobil instead chose to invest in hydrogen and lithium extraction, since the skills needed are very similar to those used in extracting oil. While the mining of these elements comes with its own environmental concerns, both are vital components in the production of battery-powered vehicles.

A second factor affecting profitability is the high initial investment costs for renewable projects combined with the low prices of solar and wind power. This means that it takes years, or even decades, for investors to see return on investment.

Improving infrastructure

While these energy sources have become less expensive to generate in recent years, they tend to produce energy during the same time periods. For instance, on a particularly windy day, the wind energy produced will outstrip demand, which drives down prices. Additionally, wind turbines are increasingly being turned off as the grid is unable to cope with this surplus.

One solution to this issue is using interconnectors, high-voltage direct current (HVDC) cables that connect the energy grids of different countries, enabling the movement of renewable energy to international markets where demand is higher. HVDC technology is ideal for long-distance transmission with minimal energy losses.

In HVDC systems, resistor technology plays a vital safety role by dissipating excess wind energy during faults, helping to stabilise the grid and prevent damage. DC neutral earthing resistors also add a further layer of protection to HVDC converter transformers, both offshore and onshore, by managing fault currents and ensuring system reliability.

Ultimately, privately owned oil and gas companies are more likely to be driven by shareholder interests than they are by environmental targets. However, by ensuring that the correct infrastructure is in place to make the most from the renewable resources, it’s possible to improve both sustainability and profitability.

Looking for a reliable resistor partner for your HVDC project? Get in touch with our knowledgeable team.

CR729

Keeping the UK’s most ambitious energy project afloat

KEEPING THE UK’S MOST AMBITIOUS ENERGY PROJECT AFLOAT

DBRs for tidal power projects

HOW RESISTORS ENSURE RELIABILITY IN TIDAL PROJECTS LIKE MERSEY TIDAL POWER

The UK’s clean energy transition is set to take a major leap forward with the Mersey Tidal Power project, a proposed development that could become one of the largest in the world. But what challenges does a project of this scale present for electrical infrastructure? This article explores how resistors can help stabilise the grid and extend component lifespan to ensure the long-term success of tidal projects.

The Mersey Tidal Power project is one of the UK’s most ambitious renewable energy projects to date. Inspired by successful tidal range developments such as La Rance in France and Sihwa Lake in South Korea, it aims to replicate the long-term viability of tidal power on an even larger scale. Using a barrage-style turbine array to harness the immense power of the river Mersey’s tides, the development could generate up to one gigawatt (GW) of clean energy. However, despite its promise, the scale and ambition of the project raises several challenges that require careful consideration.

STABILITY AND RELIABILITY DEMANDS

Unlike other renewable sources, tidal power generation follows a predictable pattern, being governed by the lunar cycle. However, tidal energy still experiences variations in output due to the changing intensity of tidal flows. Managing these fluctuations, particularly at such a scale, requires highly efficient electrical infrastructure.

Any variation in energy production needs to be carefully managed to prevent fluctuations from causing inefficiencies or disruptions in power transmission. Without this precise control, power surges or dips could destabilise the grid, undermining the reliability of the entire energy network.

The Mersey Tidal Power project’s sheer scale also introduces technical demands beyond standard renewable installations. With an expected operational lifespan of over 120 years, all components — especially electrical systems — must be designed to withstand extreme marine conditions. Saltwater corrosion and high mechanical stresses from strong tidal currents place exceptional demands on electrical equipment. Ensuring system longevity requires components that are not only resilient but also capable of maintaining performance over decades of operation.

ANCHORING TIDAL POWER

The success of large-scale tidal energy projects depends on a responsive and reliable electrical system. Dynamic braking resistors (DBRs) play a key role by absorbing excess energy during peak tidal flow. When tidal currents are at their strongest, turbines can generate more electricity than the grid can immediately use. DBRs convert this surplus electrical energy into heat, safely dissipating it to prevent voltage spikes or overloading transformers. By smoothing out power delivery, they help maintain a consistent and reliable supply of electricity, ensuring that tidal energy can integrate seamlessly with the wider grid.

Beyond grid stability, resistors also protect the physical infrastructure of the turbines. Rapid changes in water flow, such as shifts between ebb and flood tides, can create sudden torque variations on turbine blades and drive systems. DBRs help regulate these mechanical stresses by slowing the turbine’s rotational speed in a controlled manner, reducing wear on bearings, shafts and other moving parts. 

Given the vital role that resistors play in tidal power generation, their durability in harsh seawater is essential. High-quality marine braking resistors are engineered to withstand the extreme conditions of tidal power systems, including corrosion, heat and mechanical wear. Designs often incorporate sheathed mineral-insulated elements to protect against physical damage and environmental degradation, alongside marine-grade stainless steel to resist saltwater corrosion. These durable materials allow resistors to maintain peak performance for decades, even in the demanding conditions of tidal power projects.

While the scale of the Mersey Tidal Power project raises technical challenges, the proposed development is a bold testament to the UK’s commitment to clean energy. As the government increasingly supports tidal power as part of its long-term energy strategy, this project could pave the way for widespread adoption of tidal infrastructure. Throughout this transition, resistor technologies are expected to play an important role in ensuring the stability of the grid and the longevity of power generation systems.

CRE596