The warnings have been there for some time: the huge effort behind the transition from fossil fuels to the likes of wind and solar energy risks being in vain if the power produced gets stuck in an antiquated grid system that cannot cope. “Grids were not originally set up for such a fast-paced energy system; their tools and processes were developed in a slower, less volatile world,” says a 2024 report by management consulting firm McKinsey. “Increased penetration of intermittent power sources, such as solar and wind, have caused a higher utility frequency and voltage volatility,” it adds, commenting that integrating renewables into grids is “no easy task”.

“The legacy grid was designed for one-way power flow from large synchronous plants to passive consumers. Solar-PV and wind inject highly variable, often DC-originating power at the distribution edge, so voltages and currents swing rapidly,” explains Jonatan Peris Rivas of the Spanish technology centre CIRCE, and project manager of the EU’s SSTAR project to develop Solid-State Transformers (SSTs), an emerging technology capable of converting low-frequency power to high-frequency power. “Conventional 50 Hz transformers cannot regulate these swings… The net result is rising losses, curtailment of surplus renewables and growing stability risks,” he adds.

The accelerating global drive to bring about clean energy transitions and meet net zero targets is led by the power sector, with record deployment of renewable sources. In practice, that means a huge and growing demand for electricity. “The transition to RES (renewable energy sources), coupled with economic growth, will cause electricity demand to soar—increasing by 40 percent from 2020 to 2030, and doubling by 2050,” says McKinsey’s study. “The deployment of electric vehicles, greater use of electric heating and cooling, and developing of hydrogen production via electrolysis are new drivers of demand growth,” says the International Energy Agency (IEA) in its 2023 report, Electricity Grids and Secure Energy Transition.

Wind and solar PV (photovoltaics) are projected to account for “over 80% of the total increase in global power capacity over the next two decades… compared with less than 40% over the past two decades,” the IEA goes on. It paints a picture of new energy generating systems in often-remote locations: “solar PV projects in the desert and offshore wind turbines out at sea… far from demand centres like cities and industrial areas.” Hence the focus of both IEA and McKinsey reports on the need to modernise power grids to meet the enormous challenge of bringing electricity to the consumer, accompanied by warnings that investment is lagging behind. For the IEA, “the role of grids in energy transitions is just as foundational as that of solar panels, wind turbines and electric vehicles” and yet has been neglected. Its executive director has likened the situation to making “a very efficient, very speedy, very handsome car” – but forgetting “to build the roads for it”.

In practice, building those energy “roads” to achieve energy and climate goals “means adding or refurbishing a total of over 80 million kilometres of grids by 2040, the equivalent of the entire existing global grid”. The IEA outlines the technological, operational and regulatory steps that need to be taken: “Grid expansion and modernisation needs to happen at speed and scale, and building new grids needs to go hand in hand with improved use of existing infrastructure and new technologies.”

As CIRCE explains, Solid-State Transformers are a key component of new equipment necessary to integrate renewable sources into the energy system to help it meet the challenges ahead. “SSTs offer several advanced capabilities that conventional 50 Hz transformers lack,” says Jonatan Peris Rivas. “An SST replaces the iron-core, low-frequency stage with a stack of power-electronic converters…. This ability to convert currents (AC ↔ DC) and operate at higher, precisely set voltage levels is essential when you must connect DC renewables or batteries without extra converters.” His peers concur: “SST has many advantageous features including power flow control, voltage regulation, reactive power compensation, harmonic block, fault current limiting, galvanic isolation, and bi-directional power flow,” wrote one group of scientists in a 2023 report. McKinsey lists SSTs as an example of advanced grid technologies that can aid the integration of renewable energy sources.

The SSTAR project, which has been carrying out laboratory tests in Portugal and Spain, is aiming to publish results in February 2026. Among its specific objectives are to develop a new biodegradable dielectric fluid which will bring up to 50% CO2 savings compared to traditional mineral oils, and improved environmental sustainability. As for how SSTs will be used in everyday life, Peris Rivas mentions “concrete applications such as smart grids, microgrids, fast-charging stations for electric vehicles, direct interfacing with renewable energy sources (like solar and wind), railway electrification, and data centres.” He adds: “These innovations are being tested and validated to prepare for real-world deployment, with the ultimate goal of integrating more renewable energy into power grids, reducing fossil fuel dependence, and contributing to a more flexible and efficient electricity infrastructure.”
The warnings of the consequences of inaction to update and expand power grids are clear. “Without an additional policy focus on accelerating investment beyond existing plans, there is a risk of delays to the grid expansions needed around the globe,” the International Energy Agency says in its 2023 report. “Delays in grid investment and reform would substantially increase global carbon dioxide (CO2) emissions, slowing energy transitions and putting the 1.5 °C goal out of reach.” For McKinsey, “taking advantage of renewables requires a power grid that can accommodate these intermittent energy sources. Operators have a way to go to make this happen, but they can start now by rethinking their planning, connections, and operations and coordinating across stakeholders to construct a global net-zero power grid for the future.”

Jonatan Peris Rivas argues that the SSTAR project is making a significant contribution. “Solid-State Transformers (SSTs) have strong potential to modernize the power grid by enhancing its flexibility, efficiency, and reliability,” he says. “While challenges remain, such as high costs and the need for updated regulations, their adoption is crucial for achieving long-term energy and climate goals.”


Contacts:
Project coordinator:
Jonatan Peris Rivas, CIRCE, jperis@fcirce.es


Communication Manager:
Ilaria Bonetti, ICONS ilaria.bonetti@icons.it

Project website: https://sstar-project.eu
LinkedIn: https://www.linkedin.com/company/sstar-project/