The definition of solar energy is simple: solar energy is the energy emitted from the sun. Most people understand that the sun gives life to all things on this planet through its energy, seen as light and felt as heat, but the sun also produces many other things.

The source of solar energy is the nuclear reaction in the center of the sun, continuing for billions of years. Photons are created through the fusion of two Hydrogen atoms to form one Helium atom in the sun's core. They will eventually be what generates solar power, but not until they are able to escape from the sun.

It generally takes a photon over a million years to escape from the center of the sun to the sun’s surface. Once at the surface, the photons are sent hurtling out into space in all directions, and some of them are intercepted by the Earth.

The basic explanation is that solar panels use a network of Photo-Voltaic (PV) cells to capture the sun’s energy, which is then converted to electricity and used to power pretty much anything you want. However, that doesn’t really explain the science behind the panels or what all these terms mean. Firstly, let’s look at just what PV cells are. Photovoltaic (from ‘photo’ meaning light and ‘voltaic’ meaning electricity) cells are manufactured from layers of semi-conducting material, usually silicon – this is because striped down silicon is ideal for the transmission of electrons, which is essentially how solar panels operate.

Sunlight contains photons which are absorbed by the silicon, or other semiconducting material, when they hit the solar panel. The electrons in the silicon’s atoms are then displaced and a number are released, allowing electric fields in the cells to pull the free electrons into a current. The metal contacts on the top and bottom of the PV cell are then able to channel these electrons to a load, generating electricity. That’s the science bit but there’s more to a successfully functioning solar panel than that.

Silicon is a particularly shiny material, which would ordinarily reflect the photons rather than absorb them. An anti-reflective coating is therefore applied to the surface to encourage as much absorption as possible – the more photons, the more electricity can be generated. This is also why the panels themselves are generally installed on a roof, preferably south sloping in the northern hemisphere and north sloping in the southern hemisphere.