Perhaps you should understand the difference between distal and proximal causes of events? Both are important. Voltage oscillation was the proximal cause. Where did this come from? It's explained in the operators own report:
> During the incident analysis, it was determined that the oscillation was not natural to the system but rather forced. This oscillation is observed with significant amplitude at a Photovoltaic Plant located in province of Badajoz (PV Plant A). At the time of the oscillations, the plant was generating approximately 250 MW. Since the oscillation was forced, it ceased once the plant stabilizes it.
"Reactive power" sounds fancy, but it just means that motors can create a drag. The power lines are giant capacitors, and capacitors have the lowest effective resistance when they are discharged. So the current is greatest when the voltage crosses the zero mark. Inductive (rotating) loads are the opposite, their effective resistance is greatest when the current starts to rise or fall. So this limits the initial inrush of the current.
But there's more! When you have a transformer and a long line, you can essentially get a boost converter. The voltage from a transformer travels through a low-resistance wire until it reaches the end, and because the line can be modeled as a series of capacitors, you essentially get a "charge pump" ( https://en.wikipedia.org/wiki/Charge_pump ). From the viewpoint of the generator you have one large capacitor, but from the viewpoint of a consumer in the middle of the line, you have two capacitors in series.
As a result, the voltage in power lines can _spike_ if there's not enough rotating load. This is called Ferranti effect, and in Spain it was the primary reason for the faults.
This is all fixable, but it requires investment and regulation. And Spain (and other countries) have been neglecting that, by incentivizing the cheapest possible generation.
The interesting thing about spain's grid is that it doesn't have that much battery compared to say the UK (the uk has about 11 gwhr which is about enough to power the entire uk for around 20mins)
The Iberian grid has <100Mw (I know mixed units) battery at the moment. This is interesting because the economics of the iberian grid means that most solar plants are in curtailment (ie told to turn off) at solar mid day prices are normally negative, at 18:00 prices are very high.
There is currently a large lucrative market in grid scale batteries being paid to charge at solar noon and getting a 30-50% premium to release the power at peak.
There are only a few companies that are able to vertically integrate solar and battery, so it'll be interesting to see how the prices shape up in the next 5 years. I expect a bunch of batteries to be built and then sold as the market changes shape.
*edit* spell
Typically ~10 seconds.
The bigger issue is if these have blackstart capability. (IE, if they can switch to generation when there is a blackout, or if they need power from the grid to start.)
Non-storage dams don't have lower lakes to pull from, and the surrounding area might not be able to support it.
plus they also need water when there are droughts, which spain is also prone to.
https://www.youtube.com/watch?v=8CwB38oLEYM
Solar Saturation & Grid Collapse: Spain's BESS Opportunity - Modo Energy
While there are certainly issues with the supply chain of certain components of renewables, those effectively cease after installation. And even hydro is not totally immune from supply issues given increasing drought frequencies across the world.
/s
As these renewables and grid change to a different configuration/inverter technology, this problem shouldn't happen again?
[0] https://www.entsoe.eu/publications/blackout/28-april-2025-ib...
So, what caused the blackput?
The root cause tree with its multiple roots on page 23 is a good start.
Working out why the regulator failed is no easy task. And fixing regulators is highly political.
You might compare against another country that successfully integrated massive solar systems such as Australia. They had a functional regulatory environment that designed their systems to handle the supply changes. Some of that was through world leading deployment of battery systems to help regulate their network.
There is a lot of specialist expertise (e.g. nera.com economic consultants) that is paid by a countries network operator to design their networks and markets. The staff within individual countries either lack sufficient analytical skills or lack sufficient political clout to make their networks deeply resilient.
And:
"With annual additions now around 1 GW, UNEF is calling for stronger momentum to maintain progress towards 2030 targets"
"Growth, however, has slowed, with only around one gigawatt added last year. To reach the national target of 19 gigawatts by 2030, deployment will need to accelerate, the association" [0]
[0] https://www.pveurope.eu/markets/spains-solar-market-hits-93-...
