What if the world ran on sunshine?

Sunshine falls on roofs, fields and deserts every day.

Solar panels can turn sunshine into electricity. What if all our electricity came from the Sun?

Every day, sunshine pours down on rooftops, farms, deserts and oceans. Solar panels can turn some of that light straight into electricity, with no fuel to burn.

So here is a big thought experiment: what if the whole world ran on sunshine? There would be a lot of sunlight to use. But the Sun is not always shining where and when people need electricity. You can follow three puzzles: day and night, storing energy, and where all the panels would go.

Solar photovoltaics convert sunlight directly into electricity. The resource is large, but it varies with the hour, the season, the latitude and the weather, while electricity demand follows people's routines.

This thought experiment asks what a grid supplied entirely by sunlight would need to work: how to cover nights and winters, how energy storage could shift energy in time, and how much land and which places the panels might use. It is about physics and engineering trade-offs; its outcomes are reasoned ideas, not forecasts.

Today, some of our electricity already comes from sunshine.

Solar panels sit on roofs and in big fields called solar farms.

Solar power is growing fast. The U.S. Energy Information Administration (EIA) reports that the world made about 2,090 billion kilowatt-hours of electricity from sunshine in 2024. China made about 40 percent of it and the United States about 15 percent.

In the United States in 2025, about three quarters of solar electricity came from large solar power plants and about a quarter from smaller systems, mostly on or near buildings. And a 2020 World Bank study found that in most countries, the sunshine available for solar power is far more than all the electricity they use today.

EIA: world solar generation grew from 0.4 billion kWh in 1990 to about 2,090 billion kWh in 2024, led by China (40%), the United States (15%), India (6%), Japan (5%) and Germany (3%). U.S. solar generation was about 389 billion kWh in 2025: 76% utility-scale PV, 24% small-scale PV and about 1% solar thermal.

The World Bank's 2020 country assessment found that practical PV potential in most countries dwarfs their current electricity demand, and that about 70 countries average more than 4.5 kWh per installed kW per day.

Let's pretend all our electricity comes from the Sun.

In the daytime, there might be lots. But what about at night? We would need to save some for later!

Imagine that every light, fridge and train runs on sunshine. At noon on a sunny day, panels might make more electricity than everyone needs. But at night they make none, and on cloudy days and in winter, less.

So a sunshine world would need a way to save daytime energy for the night, and maybe summer energy for winter in places far from the equator. It would also need room for a great many panels, on roofs and in fields. These are ideas: engineers are still working out the best ways.

A solar-only grid would face the variability EIA describes: available sunlight depends on time of day, location, season and weather. Supply would need to match demand at every moment, as EIA says grid stability requires, so energy would have to be shifted in time.

Daily shifting might rely on storage such as batteries and pumped hydro; seasonal shifting at high latitudes would be a larger problem, since seasonal variation grows with distance from the equator. Widely connected grids might move power between regions with different weather. These are reasoned ideas, not predictions.

The Sun sets every evening. Then solar panels stop making electricity.

Batteries can save electricity from the daytime, like saving snacks for later.

The grid has to make as much electricity as people use, every moment. Solar panels only make electricity when light reaches them, so the electricity needed at night has to come from somewhere else, or be saved from the day.

The EIA explains that storage systems, such as big batteries and pumped-storage hydropower, are not power plants themselves: they store electricity made by something else. And they always give back a little less than they took in. In 2022, the United States had more pumped storage than batteries, and a growing number of batteries are being paired with solar and wind plants.

EIA classes energy storage systems as secondary generation sources: they must be charged by separate generators or the grid, and they use more electricity for charging than they discharge, so they have negative net generation.

At the end of 2022, U.S. utility-scale storage included about 22,008 MW of pumped-storage hydro in 40 systems across 18 states and about 8,842 MW of batteries. Pumped storage uses grid electricity to pump water up to a reservoir and sends it back down through turbines when it is needed; large batteries can also respond in fractions of a second to steady grid frequency.

Solar farms need lots of space. Some are built on land that is not good for growing food.

Solar panels on roofs use space we already have.

The EIA lists two big limits of solar energy: the sunshine available changes with the time of day, the place, the season and the weather, and a large surface area is needed to collect enough energy to be useful.

Some solar power plants cover many acres and supply thousands of homes. Clearing land for them can affect the plants and animals living there. The EIA notes that building them on farmland that isn't good for farming, or blending them into working farms, may benefit farmers. Solar panels on buildings have very few harmful effects on the environment.

EIA identifies two limitations of solar energy: availability that depends on time of day, location, season and weather, and the large surface area required. It notes that clearing land for solar power plants can affect native habitats, that siting them on farmland less suited to farming or integrating them into farms may offer economic and environmental benefits to farmers, and that rooftop systems have minimal environmental effects.

Some solar plants also use water to clean panels, which in dry places could affect local ecosystems. A sunshine-powered world would weigh each of these trade-offs site by site.