A bright future for solar energy

The sun’s rays are the source of all the Earth’s renewable energy. This manna from heaven provides the equivalent of one barrel (159 liters) of oil per square meter per year for free – at least in sunny regions such as the Swiss canton of Valais.

Moreover, our ability to convert solar energy into electricity is increasing. This is partly because engineers are constantly making improvements to increase the efficiency of photovoltaic (PV) cells, and partly (or even mainly) because both the supply and demand for these units are growing rapidly. In 2023, almost 375 GW of solar panel capacity was installed worldwide. This is four times more than in 2019 and 20 times more than in 2010. It is a lot, but still not enough.

Christophe Ballif, head of EPFL’s Photovoltaics and Thin Film Electronics Laboratory (PV Lab) in Neuchâtel, puts these numbers into perspective: “By 2050, we will have to replace 80% of the fossil fuels we use today with clean energy. This is a huge challenge. If we continue at the same pace as in 2023, when 375 GW of solar power capacity and 110 GW of wind power capacity were installed, it will take us about 120 years to achieve the energy transition in 30 years – in light of the climate crisis, this is more reasonable The time interval. This means that we will have to increase the annual capacity of photovoltaic installations almost fourfold, to 1,500 GW.” But he thinks it’s possible: “China has invested between $60 billion and $80 billion in the last three years in new production capacity for everything from polysilicon to complete photovoltaic units. They should achieve the required production capacity no later than next year. However, this Herculean supply-side effort will actually come a little too soon. We are clearly in a situation of overcapacity.

The combination of sun and wind

Solar energy will account for a rapidly growing share of the global energy mix, which is good news. In Switzerland, the government has introduced targets for the transition to solar and other renewable energy by 2050. The goal is to provide a renewable supply of 45 TWh, or more than half of the country’s total energy demand based on current levels. Experts agree that the most effective way to achieve this goal is to combine solar power with other forms of clean energy: hydropower, of course, but ideally also a significant amount of wind power.

Before solar and wind energy can be used in power grids, they must be combined with at least one storage system, such as batteries, dams and syngas. In particular, when it comes to batteries (including electric vehicle batteries), China is once again a global manufacturing powerhouse. Here too, the country has made huge investments in new facilities. “China is flooding the market and overproducing to the point that prices for both batteries and solar modules are falling,” Ballif says. “This is good for consumers and for the energy transition in general, but it will create a form of dependency that we do not want. Governments in other regions, including Europe, must build and expand their production capacity to make the market more resilient.”