Neglecting the role of grids in the energy transition has been likened to developing a sleek new car that’s all revved up with nowhere to go. Building energy “roads” to integrate solar and wind power and cater for the demands of electric cars, heat pumps and so on has been compared to overhauling the entire existing global grid. Solid-State Transformers (SSTs) are key to adapting distribution and transmission networks to the new era. The EU-funded SSTAR research project, which has been working on tangible innovations to improve their efficiency, flexibility and sustainability, ends in late February 2026. Project manager Jonatan Peris Rivas of the Spanish technology centre CIRCE says new intelligent technology is nearing readiness for real-world deployment.

You're coming up to the end of the project. Overall are you happy with how it's gone?

Yes, I’m happy with the commitment of all partners. We’ve been carrying out the last technical steps of the project that’s been running for the past three years. This is an innovative project with technical challenges: Integrating solid-state transformer technology into real-world applications remains a challenge at medium- and high-voltage levels, as most solutions available on the market today are still limited to low-voltage use. Through this research project, we aim to progressively address these gaps by improving the technology and advancing our understanding of the key technical barriers that need to be overcome for future market uptake.

Why are these technical advances necessary? What's wrong with power grids as they stand and what are the challenges that they face in years to come to adapt them to the new world of energy transition and the widespread use of renewables?

Current technology is focused on low voltage, which doesn’t allow for higher flexibility that’s needed in power grids. With this kind of project, using SSTs to achieve higher voltage levels, we need to understand how to improve and to make this kind of technology more intelligent to distribute into grids, into future transmission systems with higher voltage, with higher efficiency, with higher flexibility. We’ve been combining this technology with a clear focus on scalability, reliability and sustainability which are currently really limited in the grids. This is about introducing more intelligence and flexibility into the energy transition, moving from passive components to active and intelligent ones to better regulate power flows and improve power quality and reduce fault. You have more digitalised control as well.

You provided an update in August 2025 saying that tangible innovations had been developed to improve power grids particularly in three areas: a new prototype transformer, a greener insulation fluid and decentralised converter control. Can you explain the significance of these three milestones?

These milestones represent a significant step forward in creating smarter and more sustainable energy infrastructures. This is the overall objective of this project: we are trying to allow the grid to move from a passive component to an active and intelligent node. Our main objective is trying to regulate power flows, improve power quality, facilitate the integration of the renewable energy storage system with several applications in the market. Flexibility is essential. SSTAR aims to demonstrate that this advantage can be transferred to real grid environments via laboratory prototypes. This kind of simulation is the first step towards understanding how to integrate this into actual grids. Right now with our partners, we are carrying out the experimental validation of two prototypes in our laboratories in Spain and Portugal.

What else can you say about what those laboratory tests have achieved?

We don’t have all the results yet; we’ll be able to report them in February at the end of the project timeline. But testing has covered several levels: electrical tests to validate power capability, efficiency and behaviour under different conditions; thermal and dielectric tests to validate critical aspects of the technology especially when it comes to operating the technology at higher voltage. We are also assessing electromagnetic difference, fault behaviour and protection systems: the goal is not only to demonstrate functionality but also to ensure a safe, stable and predictable operation.

There were several specific objectives at the outset: for instance, 50% CO2 emission savings from the new dielectric fluid compared to traditional mineral oils. Can you say anything about the progress that's been made in that area?

We will see because this is the first time that we're trying to prove this kind of technology, so it's really challenging. I don’t think we have to be 100% focused on the figures. Obviously, that's the main objective and we must work to achieve it, but if we don’t we need to understand the reason, the root cause in order to progress. It's crucial to understand the lessons learned with this kind of European research project.

You've said that the innovations being tested and are being prepared for real-world development. What sort of time scale are we looking at?

In validating prototypes in this kind of environment we cover the full spectrum, from research-oriented laboratory testing to a more industry-driven perspective. It’s essential to prepare for a transition to a higher technology readiness level. We have prepared a health index for power electronic components: the objective is to assess component degradation and anticipate potential failures, a key requirement for systems before going to the real market. All this can help improve the integration of this technology into the grids.

Could the technology help prevent mass outages such as the blackout Spain and Portugal experienced in April 2025?

Yes, exactly. Some months ago, the electricity was cut here for several hours all over Spain. Many people pointed the finger at renewable energy for being responsible without knowing what really caused the blackout. Yet the truth is that renewable energy and this kind of technology are the real solutions for these issues! We must implement a lot of steps that we are currently researching but these innovative projects are the main solution to make the electrical grid more intelligent and to know how to react in such cases. This can happen again because unfortunately we cannot assure 100% efficiency in this technology, but with more investment in technology the probability is really low, and our daily life can improve a lot.

There have been lots of warnings about the consequences of a lack of investment in power grids to make sure that they are adapted to the new world. How do you see the situation?

If we are trying to achieve certain goals with some innovative project, we need investment to scale up from technological research in a laboratory to the real market. Many of us are not aware about the implications of this kind of technology progress until we have some difficulties in our real lives, as we experienced with the blackout in Spain: for instance, people were without water for several hours because there was no electricity for the pumps to work. So technology and investment in research are crucial to progress in our daily lives.

Looking ahead, the analogy has been made that with renewables it's like having a brand-new racing car but unless you adapt the power grids then there's no road to drive it on. Are you confident that road is now being built?

Yes, we’re on the right path. We’ve been working for several years with the European Commission on the kind of European project that is crucial to make progress. I think that we are building a better world with this kind of technology. We must introduce sustainability into our daily lives and collaboration at European level, involving the expertise of our companies, is essential.