Solar Energy Facts

Solar power is one of the cleanest forms of energy. It emits zero greenhouse gases or other pollutants, uses no water and produces no waste. In the face of the daunting challenge of climate change, solar power will become an important part of our energy future.

Solar power plant, Mojave Desert, USA.
© Kevin Schafer / WWF

Going solar

There are numerous ways to convert the sun’s energy into heat and electricity.
Passive solar using sunlight for energy without the use of active mechanical systems ensures that buildings make the most use of the sun to regulate light and temperature.

Solar thermal collectors use the solar radiation falling on them to heat tap water. They can also serve for space heating.

Different types of photovoltaic modules convert solar radiation directly into electricity. Such modules are increasingly integrated in buildings, and can, for example, be used as roof tiles.

Different types of solar thermal power plants use solar heat by concentrating solar radiation – such as through mirrors focused on a solar power tower or by means of parabolic troughs to heat up water and conveying the steam to a turbine.

And very simple mirror-based systems can help in saving gas, kerosene or wood through solar cooking.

A growing trend

These various solar technologies are growing in scale. Total PV capacity amounted to 16 GW in 2008, and large plants (over 50 MW) have been built in several places.

Solar thermal power plants are mushrooming in the US and in Spain, and China takes the lead in solar heating with 70% of existing global capacity.

Solar heat holds a great promise for cities, where air pollution can be a big problem. And in many sparsely populated off-grid areas, passive solar design, solar heating, cooking and photovoltaics are starting to be used.

WWF envisages a future where large-scale solar electricity plants are connected to super grids to meet energy needs throughout the world.

In theory, the entire present energy consumption of the world could be met by an area smaller than 1% of the world’s deserts if they were covered with solar thermal electric plants.

	© Michel GUNTHER / WWF
Solar heating system on a village house in Nepal.
© Michel GUNTHER / WWF

Did you know?

Ancient Greece and Rome were already using passive solar design for their housing. The first solar photovoltaic cell was invented in the 1950s. Since then technologies have evolved with several different systems that use power generated from the sun.

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