Guides to what is happening on Europe's grid

On 28 April 2025 Spain and Portugal lost almost all of their electricity within seconds. Less than three months earlier Estonia, Latvia and Lithuania had cut their last synchronous tie to the Russian grid and joined the continental system. In both, the links to neighbouring grids were part of the story, the thing this site maps.

The guides below take one subject at a time, with the sources for every figure.

Five subjects, one grid

The Iberian blackout. Just after half past twelve on a sunny Monday, about 31 GW of demand vanished from Spain and Portugal in seconds. The guide to the blackout of 28 April 2025 follows ENTSO-E’s investigation minute by minute, from two oscillations in the late morning to the voltage rise that tripped one generator after another. Most blackouts start with too little power. This one started with voltage climbing too high, and the guide explains why a grid full of solar at noon can struggle to hold it down.

Grid congestion. German grid operators paid a little over €3 billion in 2025 to manage bottlenecks on the transmission network, and still had to curtail about 3.5% of its renewable output. The congestion guide explains why a market that treats a whole country as one copper plate keeps colliding with wires that were laid out for coal and nuclear plants in the south and west.

Energy islands. Bornholm, the Danish island in the Baltic, is meant to collect 3 GW of offshore wind in the 2030s and pass it on to both Germany and Zealand. The energy islands guide covers the hub-and-spoke idea behind it: one set of cables that carries wind power ashore when it blows and trade between countries when it does not.

Subsea power cables. On Christmas Day 2024 an anchor dragged across the Gulf of Finland and took Estlink 2 out of service for about six months. The subsea cables guide starts from that fault and works through what a cable is made of, how it is laid and buried, and why a repair on the seabed takes months. A scroll from the sea surface down to the cable is built into the page.

The Baltic switchover. In February 2025 Estonia, Latvia and Lithuania left the Russian-controlled grid and, after roughly 29 hours running on their own, joined the continental system. The Baltic synchronisation guide tells the story from the BRELL agreement of 2001 to the morning the last lines were opened.

The five have more in common than it first seems. Each turns on the links between grids: the Iberian peninsula had too few of them, Germany has too few inside its own borders, Bornholm is an attempt to build a new kind, a subsea cable is the most exposed kind, and the Baltic states rebuilt theirs to change which grid they belong to. Each guide links to the power links involved, so the figures can be checked on the map.

Renewables and the grid

The shorter pieces further down began as articles on renewable energy in Europe. Each has since been rewritten with sources: how the EU’s rules pull renewables onto the grid, how large companies buy green power and what their certificates really change, how solar, wind and hydro plants each behave on a network, and how the casino industry has moved some of its energy use to solar. They make a lighter starting point than the long guides, and most of them link on to the power-link map where the physical side of the story sits.

Every guide opens with the key facts in four lines and ends with questions and answers, for readers who want the short version first. The figures carry their sources, and where official reports disagree, as the Spanish and European investigations of the Iberian blackout do on who carries the blame, the guide sets out both.