Could solar become the world's largest electricity source by 2050?

The forecast that turned heads

When the International Energy Agency suggested that solar could become the world's largest single source of electricity by 2050, it marked a notable shift in mainstream thinking. The agency's 2014 roadmaps examined two technologies — solar photovoltaics, which convert sunlight directly into electricity, and solar thermal electricity, which uses mirrors to concentrate heat and drive a turbine.

Taken together, and under favourable policy and cost assumptions, the roadmaps described a future in which solar overtakes every other single source of power. It was a bold statement, and it captured attention precisely because solar had for so long been dismissed as too expensive and too intermittent to matter at scale.

Why solar costs collapsed

The single biggest reason to take the forecast seriously was cost. Over the preceding years, the price of solar panels had fallen dramatically as manufacturing scaled up, factories became more efficient and competition intensified. Solar that had once been affordable only with heavy subsidy was, in a growing number of places, becoming competitive on its own terms.

Cheaper hardware changed the economics of everything downstream. Lower panel prices meant lower project costs, which encouraged more installations, which supported yet more manufacturing investment — a virtuous circle that few forecasters had fully anticipated.

Learning rates and deployment

Analysts often describe this pattern using the idea of a "learning rate": each time the total installed capacity of a technology doubles, its cost tends to fall by a roughly consistent percentage. Solar has followed such a curve for decades, and it helps explain why the technology kept beating expectations.

Deployment reinforced the trend. As countries added solar to meet climate targets and to diversify their energy supply, the sheer volume of installations drove costs lower and built the industrial capacity to go further. The roadmaps assumed this momentum would continue, supported by policy, grid investment and improvements in storage.

The important caveats

A projection is not a prediction, and the roadmaps were careful to frame their conclusions as scenarios that depended on sustained action. Several real-world challenges stand between the forecast and reality:

• solar is variable, so it must be paired with storage, flexible demand and other sources;
• power grids need major investment to handle large shares of renewable generation;
• policy support and stable regulation are needed to keep investment flowing;
• supply chains, land and materials all have to scale sustainably.

None of these is insurmountable, but each is a reason to treat the headline as a possibility rather than a certainty. What the forecast really demonstrated was that a solar-led electricity system had moved from fantasy to a serious, mainstream scenario. Our guide to renewable energy looks at how far that shift has come.

What it means for your home

For households, the long decline in solar costs has two practical consequences. First, cheaper clean electricity helps hold down the cost of green tariffs and supports the wider decarbonisation of the grid. Second, home solar has become far more accessible than it once was.

The way households are rewarded for generating their own power has changed over time. Historic support in the UK came through the feed-in tariff scheme, which has since closed to new applicants and been replaced by newer arrangements. For an up-to-date view of tariffs and how to compare them, see our tariff guides.

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