The proximal cause of the blackout was a single faulty solar inverter in a PV plant. The distal cause, however, was inappropriate disconnection of wind/solar generation and widespread cascading failure of reactive power support across the grid. Add to that a whole bunch of noncompliant transformers which tripped inappropriately, and Spanish grid operators inability to react appropriately.
The big thing with renewables is that they don't really require ongoing fuel shipments. Spain is not a large producer of any of the major fossil fuels like oil, gas and coal.
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.
I found this video by Modo Energy interesting on why Spain has so little battery right now:
https://www.youtube.com/watch?v=8CwB38oLEYM
Solar Saturation & Grid Collapse: Spain's BESS Opportunity - Modo Energy
So renewables didn't cause the blackout per the author, but according to the neutral report [0], solar and wind exacerbated the blackout.
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...
The rate of new solar capacity is falling though, according to that graph.
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-...
You should read the report, its a good description of a complex system failing complexly. (well the reasons leading up to it failing were complex)
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.