Solar energy is used in nearly every sector of modern life, from the panels on residential rooftops to the power systems on orbiting satellites. As of 2024, the world has installed well over 1,300 gigawatts of solar capacity, with China alone accounting for roughly 888 gigawatts. But raw electricity generation is only part of the picture. Solar energy heats water, desalinates seawater, grows crops, powers remote cell towers, and is increasingly built directly into the walls and windows of buildings.
Homes: Electricity, Heating, and Hot Water
The most familiar use of solar energy is on residential rooftops, where photovoltaic panels convert sunlight into electricity for everyday household needs: lighting, appliances, electronics, and air conditioning. But solar’s role in the home goes well beyond plugging into the grid. Pairing rooftop panels with a cold-climate heat pump lets you use that solar electricity to both heat and cool your home with remarkable efficiency. Heat pump water heaters (sometimes called hybrid water heaters) do the same for your hot water supply, pulling warmth from surrounding air and running on solar-generated electricity.
Solar thermal systems take a different approach entirely. Instead of converting sunlight to electricity, they use it to directly heat water or air. Flat-plate collectors mounted on a roof can warm a household’s water supply or even heat a swimming pool for months beyond the normal season. In sunnier climates, these systems can handle the majority of a home’s hot water needs year-round.
Agriculture and Dual-Use Farmland
Agrivoltaics, the practice of growing crops underneath or between solar panels, is one of the fastest-growing applications of solar energy in agriculture. The concept solves a real tension: farmland is valuable, and so is space for solar arrays. By combining both on the same plot, farmers generate electricity revenue while continuing to produce food.
Not every crop works well under panels, but many do. Research drawn from 117 studies across 25 countries has identified 12 main crop types suited to agrivoltaic systems, with shade tolerance, water use, and economic value as the key factors. High-value crops that need less space and tolerate partial shade are especially well matched for smaller or decentralized solar installations. Leafy greens, herbs, and certain berries tend to perform well because the panels reduce heat stress and lower water evaporation from the soil. For farmers in hot, arid regions, the shade from overhead panels can actually improve yields compared to open-field growing.
Water Desalination and Purification
Turning saltwater into drinking water requires enormous amounts of energy, which makes solar a natural fit for coastal and arid regions. Solar-powered desalination now operates at scales ranging from small community units to some of the world’s largest plants.
The Al Khafji plant in Saudi Arabia was the first large-scale desalination facility fully powered by solar photovoltaic energy. Its 20-megawatt solar array, spread across 90 hectares, produces 60,000 cubic meters of fresh water per day with zero carbon emissions. The Al Taweelah plant in the UAE is even larger, processing over 909,000 cubic meters daily, with a 69-megawatt solar component expected to eventually cover 55% of its total energy needs.
At the community level, solar desalination is transforming access to clean water in places that previously had none. A solar-powered plant in Kiunga, Kenya, produces over 75,000 liters of drinking water per day and serves roughly 25,000 people using a containerized solar array with battery storage that keeps the system running after dark. In South Africa’s Western Cape, the Witsand plant supplies about 150 cubic meters of potable water daily to local residents, largely on solar power alone. A solar thermal system in California’s Central Valley has processed approximately 1.6 billion gallons of salty agricultural drainage, showing that desalination isn’t limited to seawater.
Buildings: Solar as a Construction Material
Building-integrated photovoltaics, or BIPV, replace conventional building materials with surfaces that generate electricity. Rather than mounting panels on top of a finished roof, BIPV systems are the roof, or the windows, or the facade. The U.S. Department of Energy describes BIPV as an emerging set of applications where solar generating materials are built into skylights, balustrades, awnings, facades, and windows.
The most common form right now is parking shade structures with solar panels built directly into them. These are popular for commercial properties and campuses because they serve a double purpose: covered parking and power generation. For buildings with limited or shaded rooftop space, solar facades and awnings offer an alternative that captures sunlight from vertical or angled surfaces throughout the day. Solar windows, which use semi-transparent photovoltaic layers, are further along in development and beginning to appear in commercial high-rises.
Satellites and Space Exploration
Solar power is the dominant energy source in space. Over 90% of all small satellites launched as of 2021 relied on solar panels paired with rechargeable batteries. The reason is simple: in orbit, there’s no atmosphere to filter sunlight, making solar collection extremely effective.
The solar cells used on spacecraft are far more advanced than those on a residential roof. While typical home panels convert about 20% of incoming sunlight to electricity, satellite-grade cells from manufacturers like SpectroLab achieve efficiencies above 32%. These triple-junction cells are significantly more expensive, but weight and size constraints in space make that trade-off worthwhile. Every square centimeter of panel needs to produce as much power as possible when you’re launching hardware at tens of thousands of dollars per kilogram.
Remote and Off-Grid Infrastructure
In areas without reliable electricity grids, solar energy keeps critical infrastructure running. Telecommunication towers are a prime example. For many years, off-grid cell towers depended entirely on diesel generators, which required constant fuel deliveries to remote locations. Solar photovoltaic systems have now been installed on telecom masts for over a decade, paired with battery storage that captures daytime energy for overnight use.
The same principle applies to weather monitoring stations, rural medical clinics, highway call boxes, and water pumping stations. Solar panels paired with batteries create self-contained power systems that can operate indefinitely without fuel supply chains. Solar street lights have become a standard feature in parks, communities, and along roads in both developing and developed countries, eliminating the need to trench electrical wiring to each light pole. Solar-powered traffic signals serve a similar function, staying operational even during grid outages.
Transportation
Solar energy in transportation is still largely supplemental rather than primary, but its footprint is growing. Solar Impulse 2, a solar-powered aircraft, completed a full circumnavigation of the globe, demonstrating that sustained solar flight is technically possible. PlanetSolar, the world’s largest solar-powered boat, completed a similar global journey by sea.
On a more practical level, solar is entering freight shipping. Companies like Japan’s Nippon Yusen Kaisha have begun adding solar panels to cargo ships, using them to supplement diesel engines and reduce fuel consumption. Solar-powered barges are being developed for river networks, where shorter distances and calmer waters make full electric operation more feasible. Cities including Sydney and Bangkok operate solar-assisted ferry boats for passenger transport across waterways. On land, solar-powered bus stations and tram systems are reducing the carbon footprint of urban public transit, using rooftop arrays on stations and depots to power lighting, signage, and vehicle charging.
Which Countries Use the Most Solar Energy
China dominates global solar capacity with nearly 888 gigawatts installed as of 2024, roughly five times more than the next closest country. The United States sits second at about 177 gigawatts, followed by India at 97 gigawatts, Japan at 92 gigawatts, and Germany at 90 gigawatts.
Raw capacity doesn’t tell the whole story, though. Germany generates about 14.9% of its total electricity from solar, the highest share among the top five. Japan draws 10% of its grid power from solar. China, despite its massive installed base, gets 8.3% of its electricity from solar because its overall energy demand is so enormous. The United States is at 6.9%, and India at 6.5%. These percentages are climbing year over year as new installations continue to outpace growth in electricity demand.