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One of the most transformative changes in technology over the last few decades has been the massive drop in the cost of clean energy. Solar photovoltaic costs have fallen by 90% in the last decade, onshore wind by 70%, and batteries by more than 90%.

These technologies have followed a “learning curve” called Wright’s Law. This states that the cost of technology falls consistently as the cumulative production of that technology increases.

The chart shows the perfect example of this for solar power. This data comes from the International Renewable Agency, Greg Nemet, and Doyne Farmer & François Lafond.

On the horizontal axis, we have the cumulative installed capacity of solar panels, and on the vertical axis, the cost. Both are measured on logarithmic scales, and the trend follows a straight line. That means the fall in cost has been exponential.

Costs have fallen by around 20% every time the global cumulative capacity doubles. Over four decades, solar power has transformed from one of the most expensive electricity sources to the cheapest in many countries.

Learning curves: What does it mean for a technology to follow Wright’s Law?

Technologies that follow Wright’s Law get cheaper at a consistent rate, as the cumulative production of that technology increases.

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The International Energy Agency (IEA) just published its latest annual Global EV Outlook. It provides its final estimates for sales of electric vehicles worldwide in 2023.

The IEA estimates that almost one in five (18%) cars sold in 2023 were electric — double the share from just two years earlier.

There are significant differences in adoption worldwide. This chart shows new sales shares by country. In Norway, more than 90% of new cars were electric. In China, it was almost 40%; in the European Union, 22%; and in the United States, just 10%.

These figures include fully electric vehicles and plug-in hybrids. You can find this data broken down by vehicle type in this chart.

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France generates two-thirds of its electricity from nuclear power. As the chart shows, that’s far more than the global average, just under 10%. Even though its share in France has declined slightly in recent years, it’s still its dominant power source.

Nuclear power is a low-carbon electricity source, allowing France to have a very clean electricity mix for decades.

Per unit of electricity, France emits far less carbon dioxide (CO₂) than its neighbors and has some of the lowest-carbon power in the world. The global average is 438 grams of CO₂ per kilowatt-hour of electricity generated. In France, this figure is 85 grams.

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