If you fly over Cochin International Airport in Kerala, India, you will find yourself staring down at over 46,000 solar panels. The airport, India's seventh busiest, last year became the first airport in the world to run completely on solar power.

It started as a pilot project in 2013 with 400 panels on the airport rooftop, an attempt by management to lower the airport's energy bills. After the installation of a 12 megawatt solar plant, the airport was able to run entirely on solar power.

The airport has now stopped paying for its electricity altogether, and even sends energy back to the grid.

Solar energy has become a cheap option in India - the price has dropped to a similar level to that of coal.

India's Prime Minister Narendra Modi has said the country’s investment target for the source of renewable energy will be increased to $100 billion, five times greater than current levels, scaling solar power to more than 10% of India’s total energy sector by 2022.

The successful project has inspired other airports both nationally and internationally to invest in renewable energy. Kolkata's international airport in India is now also looking to build a solar plant to reduce its electric bill by a third.

South Africa recently opened the continent's first solar-powered airport in George, in the Western Cape. It's expected to save an excess of 1.2 million litres of water every year, and will contribute to around 40% of the airport's electricity needs.