Since the turn of the century, the expansion of solar power has surpassed expectations, more than any other energy source.
Once extremely expensive and only used in remote regions, space travel or pocket calculators, today's solar modules — easy to set up and operate — generate cheap electricity all over the world.
Global solar energy capacity has skyrocketed over the last decade:
- 228 gigawatts in 2015, providing 1% of the world's electricity
- 759 GW in 2020, or roughly 3% of global energy demand
- 2,919 GW in 2025, according to estimates — solar now supplies about 10% of the world's energy, more than nuclear at 9%
The energy source is still growing exponentially, and if it continues at current rates, global capacity could hit 9,000 GW by 2030 — enough to meet more than 20% of the world's energy demand.
China leading the way
China is first in the world when it comes to solar capacity, by far. The country installed 315 GW of new panels in 2025, according to the Chinese energy authority, bringing total capacity to around 1,300 GW. More than 80% of all solar panels are currently produced in China.
Data from Taipei-based LowCarbonPower shows that 11% of China's electricity now comes from solar energy. Over the last decade, the share of highly polluting coal power has dropped from 70% to 56%. That's due in large part to the country's strong expansion in renewable energy, especially solar and wind.
EU expanding solar grid
The European Union, with 406 GW capacity, ranks second in the world when it comes to solar energy expansion. In the EU, solar energy covers roughly 13% of the bloc's electricity demand. Coal only meets 9%, a big drop from 2015, when it still generated a quarter of the EU's power.
Leading the way in Europe are Greece, Cyprus, Spain and Hungary, each generating more than 20% of their electricity from solar. Even Germany, with fewer hours of sunlight, is at 18%.
With its 119 GW, Germany is the European leader when it comes to installed solar modules, followed by Spain with 56 GW.
Despite Trump, US solar in third place
Even with renewable energy being undermined by the Trump administration, the US still ranks third in the world when it comes to solar energy expansion.
With its 267 GW, the US can supply about 8% of its total electricity demand. In 2015, it was only at 1%. Over the last 10 years, the percentage of coal power has dropped by half, from 34% in 2015 to 17% in 2025.
Solar also growing in India, Pakistan and Brazil
India, in fourth place with 136 GW of solar, now generates some 8% of its electricity for its population of 1.45 billion. Japan follows in fifth place, with a solar capacity of 103 GW covering 11% of its electricity demand.
Across the Pacific, Brazil is also building out its solar capacity and is now able to generate around 10% of its national electricity supply. Together with hydropower, wind and biomass, 88% of the country's power comes from renewable sources.
In 2015, Pakistan and South Africa each produced less than 1% of their electricity from photovoltaic panels. Ten years later, that has risen to 20% and 10% respectively.
Electricity from solar is significantly cheaper
In just one hour, the sunlight that hits the Earth delivers more energy than humankind would need for an entire year. By installing solar panels on less than 1% of the world's surface, we could cover the world's entire energy demand. And solar is getting ever cheaper.
More efficient modules and mass production have pushed prices down by around 90%, meaning solar is the cheapest form of electricity in many parts of the world.
In sun-drenched regions, large-scale solar parks can produce electricity for around 1 euro cent (1 US cent) per kilowatt-hour. In Germany, it's between 4 and 5 cents.
Electricity from rooftop solar panels is often significantly cheaper than electricity from the common power grid, and in many European countries it now costs less than half the average electricity price. Storing solar energy in batteries adds an extra 2 to 3 cents per kilowatt-hour.
According to data from Germany's Fraunhofer Institute for Solar Energy Systems, the current price for nuclear power is between 14 and 49 euro cents per kilowatt-hour (16-56 US cents). Coal power costs between 15 and 29 cents per kilowatt-hour, while natural gas is between 15 and 33 cents.
Solar power also changing transport, heating
In 2024, power stations with a total capacity of 632 GW were added to the global grid. Of that, 72% was solar power, followed by wind at 18%, gas at 4%, coal at 3%, hydro at 2% and nuclear at 1%.
Inexpensive solar power is also changing the way we heat our homes and get around. Electric vehicles can be significantly cheaper to operate, when charged with solar energy from rooftop panels at home. In Germany, the savings can add up to more than 80% when compared with diesel or gasoline-powered cars.
Keeping a building warm with a heat pump is also generally more advantageous than heating systems that run on oil or gas. In the EU, households can usually save more than 30% on heating bills. If the electricity to run the heat pump comes from the owner's own solar panels, those costs sink even further.
Solar projected to be world's most important energy source
Many early forecasts greatly underestimated the growth of the solar industry. In its annual global energy analysis in 2020, the International Energy Agency wrote that worldwide solar expansion would hit around 120 GW in 2024. In reality, a whopping 597 GW were installed that year, nearly five times as much as predicted.
Energy experts now believe that solar power will eventually become the world's most important power source. It remains to be seen, however, how fast this shift will take place.
Researchers at the Lappeenranta-Lahti University of Technology in Finland have worked out what a globally cost-effective energy supply could look like. Based on their model, 76% of the world's energy would come from solar. Wind power would make up an additional 20%, with the rest coming from hydro, biomass and geothermal energy.
Infrastructure, digitalization challenges ahead
Industry experts have said the transition to electric vehicles and the widespread use of electric heat pumps, among others, are likely to more than double the world's demand for electricity by 2050.
This will require the expansion of electricity grids, including solar, and the development of battery storage for nighttime use. But the world will need significantly more storage capacity overall. Electric car batteries could eventually serve as intermediate storage, supplementing power grids.
Rapid digitalization will also be crucial for a cost-effective electricity supply, enabling optimal coordination of electricity consumption and generation. That would allow, for example, electric vehicles to automatically begin charging when there is a particularly high supply of inexpensive solar power in the grid.
This article was originally published in German.