What is solar energy?


The Sun covers our planet in light and warmth. A mixture of heat and light from the Sun can be used as energy to heat water and make machines work. Energy from the Sun is called solar energy. Solar means to do with the Sun.

The Sun is a blazing star.

This huge burning ball of gas is our nearest star. Even though it is 150 million km away from Earth, the Sun can shine so brightly that you need to shade your eyes from its light. Sunlight can feel hot on your skin. You need to wear sun cream to protect your skin.








Energy makes things work. You need energy to throw a ball.

Without energy, nothing works. Everything needs energy. There are many types of energy. The Sun’s energy helps plants and flowers to grow. We eat plants and other foods. The energy from food gives us the energy to throw a ball and run around.





The Sun’s heat dries wet clothes.

The Sun is packed with energy. In one hour, the Earth receives more energy from the Sun than the whole world uses in a year. This energy can also be used to generate electricity. We call this electricity solar power.

Heat from the Sun

What happens to the water in a paddling pool on a sunny day? The Sun makes it warm enough to lie in without shivering. This energy from the Sun can heat the water for hot baths and showers. Heat from the Sun can be used to heat houses too.




Sunlight shines through glass in this greenhouse.

Fruits such as tomatoes and exotic plants grow well in a hot greenhouse. The Sun’s light and heat pass through the clear glass windows. When the light and heat are trapped inside the greenhouse, it feels very warm.





The Sun can be used to heat up water.

Buildings can be fitted with pipes and plates that collect the Sun’s heat on the roof. These contain a liquid that heats up quickly when the Sun shines on it. The hot liquid is used to heat water. The hot water is sent through pipes to taps, ready for use.





Some colours soak up the Sun’s heat better than others.

Paint some paper plate’s different colours, including one black and one white. Put them out in the sunshine for a few hours, and then check which one is hottest, and which one is coolest. Black clothes absorb the Sun’s heat and make you feel even hotter. Solar pipes and plates are black so that they soak up lots of heat.

Electricity from the Sun’s energy



The Sun’s energy can be used to make heat and electricity. Special mirrors gather the Sun’s energy. This energy creates heat. The heat is used to turn water into steam. Steam is used to produce electricity.







Mirrors collect sunlight.

Mirrors concentrate sunlight in one place. In a solar power tower, lots of mirrors reflect sunlight onto a special collector. The collector is filled with a liquid. The liquid stays hot for a long time. It is pumped into containers. When power is needed, the liquid flows to a heat exchanger where it heats water and produces steam. The steam turns a turbine that makes electrical energy.






These curved mirrors turn to follow the Sun.

Power troughs have mirrored surfaces. They turn to follow the Sun. Sunlight heats a liquid-filled pipe in the centre of the troughs. This is sent to a heat exchanger. The steam produced is used to create electricity.








Steam from hot water turns a turbine.

Sunlight is used to boil a liquid that heats up quickly. Steam from the boiling liquid powers a turbine. A turbine is like a water-wheel which is powered by steam instead of water. The turbine drives a generator which produces electricity for homes, offices and factories. 

Electricity from sunlight




There are other ways that the Sun’s energy is used to make electricity. Have a look at this calculator. At the top, above the numbers, there is a row of solar cells. They use energy directly from the Sun to make the calculator work.







These solar cells turn sunlight into electricity.

The proper name for solar cells is photovoltaic cells, or PV cells for short. Photo means to do with light and voltaic means to do with electricity. Just one PV cell can power a calculator or wristwatch.






Solar panels are made up of solar cells.

A group of connected solar cells is called a solar panel. Between 10 and 20 solar panels grouped together are called a solar array. Solar panels or arrays work best when they face the sunlight.








Solar cells are made from a type of melted sand called silicon.

When sunlight shines on a solar cell, the Sun’s energy makes tiny particles called electrons jump around. When the electrons jump from one layer of silicon to another in the solar cell, electricity is created. The electricity can power a lamp or machine.

Packed with Solar Power





Solar cells make enough energy to power this torch. Hundreds of solar cells connected together make enough electricity for homes and offices, or to keep small villages supplied with electricity.







Electricity from these solar cells keeps buildings heated and lit.

This housing area in the city of Amersfoort in The Netherlands runs on electricity from solar cells. It is one of the largest solar-powered housing projects in the world. It also includes solar-powered schools anda sports centre.






This space station uses solar power.

High above the Earth, solar power is used to keep spacecraft working. The solar panels create enough electricity to power the International Space Station, a large spacecraft where astronauts live and work.







Making a solar cell uses up a lot of energy.

Making solar cells is expensive and uses up energy. It takes up to four years to create enough energy from one solar cell to make up for the amount of energy used to create it! In the future, the cost of making solar cells may come down.