Europe’s renewables milestone reveals a hidden challenge

Europe’s renewables milestone reveals a hidden challenge

Europe has reached a defining moment in its clean energy transition. Wind and solar are now generating more electricity than fossil fuels, marking a major shift in the continent’s energy system. However, alongside this progress comes a growing challenge: how to integrate large volumes of variable renewable power into grids that were not originally designed for it.

A milestone with a catch

In 2025, wind and solar provided around 30 per cent of EU electricity, overtaking fossil fuels for the first time. Yet despite this achievement, Germany, France and the Netherlands still curtailed a record 3.9 terawatt-hours of renewable electricity because their networks could not absorb all available generation.

As the International Energy Agency highlights, maximising the benefits of high shares of wind and solar requires greater flexibility across generation, grids, storage and demand. Without this flexibility, renewable output is increasingly at risk of being wasted, slowing the pace of emissions reductions.

For operators, this is not just a technical issue but an economic one. Curtailment means lost revenue and underutilised assets, while periods of oversupply can lead to negative wholesale prices when generation exceeds demand. The result is a system where abundant clean energy does not always translate into usable energy.

Why curtailment persists despite record generation

The underlying challenge is the variable nature of wind and solar. Unlike conventional thermal generation, output is driven by weather conditions and can change rapidly, creating mismatches between supply, demand and available grid capacity.

At the same time, Europe’s electricity networks were largely designed around centralised, predictable power sources. As inverter-based generation becomes more dominant, the assumptions that underpin traditional grid operation, particularly around voltage stability, frequency control and fault response, are being tested. When system flexibility is limited, congestion builds and curtailment becomes unavoidable.

Engineering solutions to capture more value

Solving this challenge requires more than expanding transmission infrastructure. It also depends on a broader set of engineering solutions that help maintain stability across increasingly complex and inverter-dominated networks.

At equipment and system level, resistive technologies play a key role in supporting reliable operation. Dynamic braking resistors (DBRs) help protect wind turbines and power converters by safely dissipating excess energy during transient events such as sudden load changes or grid disturbances. Neutral earthing resistors (NERs) support safety and stability by controlling fault currents during earth faults. High-voltage filter resistors help maintain power quality by managing harmonics in networks with high levels of inverter penetration.

Load banks are also widely used to test, commission and validate the performance of generation and grid infrastructure under controlled conditions
As renewable penetration increases, fault behaviour and system response become more complex and less predictable. Ensuring that equipment performs reliably under both normal and fault conditions is becoming essential to maintaining grid stability and operational confidence.

Towards a more flexible, efficient power system

Europe’s transition past fossil fuels is a significant milestone, but it also highlights a critical truth: generation growth must be matched by integration capability. Without this, increasing volumes of renewable energy risk being curtailed or underutilised, reducing both economic value and system efficiency.

Expanding grid capacity, scaling energy storage and improving overall system flexibility will be essential. Alongside these developments, engineered solutions that support fault management, power quality and real-time system control will play a crucial role in unlocking the full value of renewable energy.

To learn how Cressall’s resistive technologies support grid stability, protection and renewable integration, speak to the Cressall team.

UK makes progress on floating offshore wind with a new 1.5 GW Celtic Sea lease

UK makes progress on floating offshore wind with a new 1.5 GW Celtic Sea lease

OW Ocean Winds has signed an agreement for lease with The Crown Estate to develop a 1.5 GW floating offshore wind project in the Celtic Sea: a major step forward for the UK’s next‑generation offshore wind capacity and clean energy goals.

Floating offshore wind promises huge renewable potential, but it also brings unique electrical protection challenges: from transient energy during turbine shutdowns to fault currents in subsea power systems.

That’s where Cressall’s wind and tidal power resistors play a vital role. Our engineered resistor solutions help manage transient loads, control switching events, and safely dissipate energy in demanding marine environments.

Whether it’s dynamic braking, load dissipation or custom high‑reliability protection, Cressall supports offshore developers and operators in delivering stable, safe and dependable renewable power.

Discover how Cressall’s resistor technologies support wind and tidal projects

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.

Choosing the right resistor element for reliable earthing protection

Choosing the right resistor element for reliable earthing protection

NER data center protection

As electrical networks become more demanding, the role of neutral earthing resistors (NERs) is becoming increasingly important. From renewable energy infrastructure to growing data centre capacity, modern power systems depend on reliable fault protection. That reliability starts with the resistor element itself.

WHY NER DESIGN MATTERS MORE THAN EVER

NERs are designed to limit earth fault currents, helping to protect equipment, maintain system stability and reduce the risk of outages. As power demand grows and networks become more complex, selecting the correct resistor technology is no longer just a specification detail, it is critical to long-term system performance.
Recent industry forecasts highlight the scale of the challenge ahead. According to the UK House of Commons Library, “Data centres currently consume around 2.5 per cent of the UK’s electricity. The sector’s electricity consumption is expected to rise four-fold by 2030.” As infrastructure demand accelerates, dependable fault protection becomes increasingly important.

UNDERSTANDING THE ROLE OF RESISTOR ELEMENTS

Within NER systems, three element technologies have proven particularly effective: edge-wound coils, wire-wound coils and expanded mesh. Each offers distinct advantages depending on the application, operating environment and fault duty requirements.
Selecting the right element is critical to ensuring safe and dependable system performance under fault conditions.

EDGE-WOUND COILS FOR HIGH-ENERGY APPLICATIONS

Edge-wound resistor elements are designed to handle demanding fault duties and high energy absorption. Manufactured from stainless steel strip wound edgewise onto ceramic insulators, they combine high performance with compact construction.
One of their key advantages is the ability to accommodate extreme thermal expansion during fault events. Temperatures can exceed 1000°C, yet the element can expand and contract freely without creating mechanical stress.
This makes edge-wound technology particularly well suited to high-voltage substations and other applications where NERs must safely dissipate large fault currents.

COMPACT AND EFFICIENT WIRE-WOUND SOLUTIONS

For applications requiring higher resistance values and lower power ratings, wire-wound elements provide a practical and economical solution.
Using nickel-chrome or chrome-aluminium wire wound onto ceramic formers, these elements offer compact construction, low inductance and quiet operation. They are often ideal for indoor installations or smaller industrial systems where space and acoustic performance are important considerations.
While they are not typically selected for the highest energy duties, wire-wound coils continue to offer dependable performance in the right operating environment.

EXPANDED MESH FOR RAPID COOLING AND RESILIENCE

Expanded mesh technology offers a different set of advantages, particularly where cooling performance and mechanical resilience are priorities.
Its open structure promotes unrestricted airflow, allowing elements to cool significantly faster than traditional stamped grid designs. The lightweight construction also provides natural shock absorption, making expanded mesh suitable for rail, offshore and other vibration-prone environments.
Low inductance characteristics further improve electrical performance, while rigid Omega-shaped designs help maintain safe spacing between elements during high-temperature operation.

THERE IS NO ONE-SIZE-FITS-ALL APPROACH

Selecting the right resistor element depends on several factors, including fault current levels, duty cycle, environmental conditions, available footprint and maintenance requirements.
Understanding how each element behaves electrically, thermally and mechanically is essential to ensuring reliable protection performance over the lifetime of the system.
With more than 100 years of resistor engineering experience, Cressall works closely with customers to design NER solutions tailored to each application and operating environment.
Need support selecting the right NER element technology for your system? Contact the Cressall team for expert guidance and application-specific advice.