While the political drama of the energy transition has centred on the United States this year, and whether Donald Trump will succeed in derailing it, something quieter but more consequential is happening elsewhere. Solar is becoming the world’s new energy superpower.
What makes solar unique is that it doesn’t rely on the centuries-old model of spinning turbines, unlike almost every other energy source. Instead, it harnesses a quirk of physics discovered in the 1830s, the photovoltaic effect, where light knocks electrons loose to make electricity.
For decades, this was an expensive curiosity, confined to niche applications such as space shuttles and calculators. But in the past 15 years, costs have plummeted so far that solar is growing at a pace unmatched in energy history.
The pace is staggering. According to Ember, an energy think tank, global solar generation has doubled in just three years, with annual growth rates consistently above 20 per cent. It has been the largest source of new electricity generation for the past three years, meeting 40 per cent of new global electricity demand last year.
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This summer, solar provided about 10 per cent of the world’s electricity, surpassing nuclear for the first time. The International Energy Agency expects it to become the single largest source of electricity by 2033, and its forecasts have consistently underestimated the rise.
Solar has become so cheap that it is becoming a big threat to incumbents; in some parts of the world it is even cheaper to build a new solar farm than to keep an existing fossil-fuelled power plant running.
In China, the world’s largest greenhouse gas emitter, exponential solar growth is finally making a dent in coal. Analysts at Carbon Brief predict China’s CO2 emissions will fall this year, as growth in solar power alone matched the rise in energy demand. In a world where sources of optimism on climate is scarce, this is remarkable.
How did solar get so cheap? Costs have fallen by about 80 per cent in a decade, continuing a long decline.
The limitless and free sunshine that reaches the Earth made the promise of solar energy clear since the discovery of the photovoltaic effect. Research was supported by government funding, and boosted during the 1970s oil crises as western countries recognised the dangers of fossil fuel dependence.
Governments including those of Germany and Japan, particularly vulnerable to energy insecurity, drove early markets through early and generous subsidies. Manufacturing shares many of the same supply-chain dynamics as microchips: mass production, learning curves, relentless cost declines. Unlike fossil fuels, which get more expensive as resources deplete, solar gets cheaper the more we build it.
And the old objection “but what about night-time?” is losing force. Solar pairs naturally with batteries, which themselves have collapsed in cost – down 40 per cent last year alone. In California, solar-charged batteries now meet much of the evening peak, and solar has overtaken gas as the US state’s largest power source.
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Meanwhile, gigawatt-scale solar-plus-storage projects are under development, which provide continuous electricity like a large, baseload coal power plant. Industry is also switching. A titanium smelting plant in the US will soon be run mainly from a solar microgrid, something unimaginable just a few years ago. Data centres, now running largely on fossil fuels, could soon follow.
This shift is not just in rich countries. For developing economies, solar plus storage offers resilience and security, and offers countries the potential to leapfrog fossil fuels altogether.
In Pakistan, for example, high electricity costs and frequent power cuts is a big drain on industry and development. But this is leading households and even factories to run instead on solar-plus-storage microgrids. This could create its own challenges to the grid by causing mass defections, threatening a “utility death spiral”.
Across Africa, notoriously deficient in modern energy, imports of Chinese panels are surging; some countries brought in enough last year to cover half their entire electricity demand. The continent could yet bypass the fossil fuel era almost entirely.
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Here in Ireland, wind remains our main renewable resource, but solar is beginning to shine here too. According to energy data gurus Green Collective, solar energy has been breaking records and cutting into fossil fuels. The cleanest days on our grid used to be blustery winter weekends; now they are often sunny summer afternoons. Rooftop panels are spreading fast. By July this year, Irish solar generation had already exceeded the whole of 2024, and is on track to cross the symbolic 1-terawatt-hour mark in 2025.
Solar power is reshaping economies, industrial systems and geopolitics, largely under the radar of mainstream debate. We are living through an energy transition that, for once, feels exponential rather than incremental.
Prof Hannah Daly is professor of sustainable energy at University College Cork
