Solar energy, which is both abundant and free, is poised to become the world's leading power source by 2050. That's thanks largely to technological advances and the unbridled manufacturing of solar cells, which bodes well for a successful energy transition.
The sun's rays are the source of all the Earth's renewable energy. This manna from heaven supplies the equivalent of one barrel (159 liters) of oil per square meter per year - at least in sunny regions, like Switzerland's canton of Valais - at no cost.
What's more, our capacity for turning solar energy into electrical power is on the rise. That's partly because engineers are constantly making improvements to boost the yields of photovoltaic (PV) cells, and partly (or even mostly) because both supply and demand for these units are booming. Nearly 375 GW of solar-panel capacity was installed globally in 2023. That's four times more than in 2019 and 20 times more than in 2010. It's a lot, but still not enough.
Christophe Ballif, the head of EPFL's Laboratory of Photovoltaics and Thin-Film Electronics (PV Lab) in Neuchâtel, puts these figures in perspective: "By 2050, we'll need to replace 80% of the fossil fuels we currently use with clean energy. It's a huge challenge. If we continue at the same pace as in 2023, when 375 GW of solar capacity and 110 GW of wind capacity were installed, then it'll take around 120 years to get there. But our goal is to accomplish the energy transition in 30 years - a more reasonable time frame in light of the climate crisis. That means we'll need to increase annual solar capacity installation by a factor of nearly four, to 1,500 GW." Yet he thinks this is possible: "China has invested between $60 billion and $80 billion over the past three years in new manufacturing capabilities for everything from polysilicon to complete solar units. By next year at the latest, it should have the required production capacity. But this Herculean effort on the supply side is actually coming a little too soon. We're clearly in a situation of overcapacity."
A combination of solar and wind
Solar power will make up a sharply growing share of the world's energy mix, which is good news. In Switzerland, the government has introduced targets for transitioning to solar and other kinds of renewable energy by 2050. The goal is to have renewables supply 45 TWh, or more than half of the country's total power demand based on current levels. Experts agree that the most effective way to reach this target is to combine solar with other forms of clean energy: hydropower, of course, but ideally also a sizable amount of wind power.
To be employed with power grids, both solar and wind power need to be coupled with one or more storage systems such as batteries, dams and synthesis gas. For batteries in particular (including EV batteries), China is once again the world's manufacturing powerhouse. Here too, the country has made massive investments in new facilities. "China is flooding the market and overproducing to the point where prices are collapsing, for both batteries and solar units," says Ballif. "That's good for consumers and the energy transition in general, but it will create a form of dependency that we don't want. Governments in other regions, including in Europe, need to build and expand their manufacturing capacity in order to make the market more resilient."
