Solar energy comes from the Sun. Every hour, the Earth receives more energy from sunlight than the entire world uses in a year. Capturing even a small fraction could power civilization. The challenge is collecting it efficiently, storing it, and moving it to where it is needed.

Two main technologies capture it. Photovoltaic panels convert light directly into electricity. Solar thermal systems concentrate sunlight to produce heat, which can generate electricity or warm water. Rooftop panels serve homes and businesses. Utility-scale farms feed the grid.

Solar has become the cheapest source of new electricity in many markets. Costs have dropped more than 90 percent since 2010. Manufacturing is dominated by China. Installation creates local jobs. The limits are land use, intermittency, and grid capacity. Solar produces nothing at night. Storage and transmission are the next frontiers.

Common technologies

• Rooftop photovoltaics
• Utility-scale solar farms
• Concentrated solar power
• Solar water heating
• Floating solar