The Sun radiates a phenomenal amount of light and heat energy in
our direction. In fact, the amount of solar energy hitting Earth’s surface in just two hours would be enough to cover all of our energy needs for an entire year.
There are two key ways of capturing and using this energy from the Sun: solar panels (photovoltaics), which convert light into electricity, and solar thermal power, which transforms the Sun’s energy into heat.
Inside a solar panel you’ll find a neat arrangement of solar cells, each around the size of a coaster, made of two thin slices of material (usually silicon), with opposing electrical charges. As the Sun shines on the cell, photons (minuscule packets of light energy) knock electrons off the silicon atoms, in what’s known as the photoelectric effect. The resulting flow of electrons forms a small electrical current in each cell.
Another way of capturing the Sun’s energy is converting it into heat. Concentrating solar-thermal power plants, for instance, use mirrors and lenses to reflect and focus sunlight to heat water or other liquids. The resulting heat is used to provide hot water to homes and businesses, or to drive a turbine to generate electricity.
The downside of solar power? It can only be generated during the day. This means that it needs to be used alongside other energy sources – or stored – in order to provide a steady supply of electricity day and night.
However, as a clean, versatile and increasingly affordable form of renewable energy, solar power is set to take the world by storm. Solar panels currently produce just 2.7 per cent of the world’s electricity, but our total capacity to generate solar power is expected to more than triple in the coming decade.
Asked by: David Reed, Norfolk
- What is the greenest energy source?
- Are electric cars any more energy efficient than conventional ones?
- How many wind turbines would be needed to power the whole of the UK?
- Could you fit solar panels to wind turbine blades?
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