The word ‘photovoltaic’ is a combination of ‘photo’, Greek for light, and ‘voltaic’, from ‘volt’, denoting electrical power. Hence it literally means ‘power from light’.
Solar PV systems use solar cells to convert solar radiation into electricity. These cells consist of one or two layers of a semi-conductor – usually silicon, an abundant element most commonly found in sand.
Atoms in the silicon are ‘knocked loose’ by sunlight, liberating flowing electrons that produce a direct electric current (DC). This is carried by cables to an inverter, which converts it to alternating current (AC) so it can be passed into the distribution grid or used at a property.
Solar power holds the potential for plentiful, cheap power for every country in the world – not just those that own fossil fuels, or can afford them. Solar is a particularly important opportunity for the African continent. If the Sahara Desert were to be covered in solar panels, the resulting energy would be enough to power the entire world.
Interest in solar is growing all the time. During 2013, 29% of the new power-generation capacity created in the US was solar. While its development may sometimes seem slow, this can be deceptive: a consistent 30% annual increase in production will translate into a 128-fold increase over 20 years, turning solar into a trillion-dollar industry. And with 5000 times more solar energy reaching Earth than we currently use, there is plenty of room for future expansion.
Part of the reason is the cost of silicon PV cells, which is falling exponentially. In addition, satellite imaging makes it easy to find and evaluate suitable sites, while storage technology is also improving all the time, so solar energy can be ‘time-shifted’ from daylight hours into night. Batteries are getting cheaper, too – the cost of lithium batteries is set to fall by over 50% over the ten years 2010–2020. Finally, there’s the strong interest in electric vehicles, which can only help to drive growth.
Overall, solar is set to play a central role in business, home life and the economy over the next 50 years. It is a technology whose time has come.
Here comes the sun.