When the sun shines

In 90 minutes, enough sunlight strikes the Earth to provide the entire world’s energy for a year. But harnessing that power directly, through solar power, has only taken off in recent years.

According to the International Energy Agency, solar panels were the fastest growing renewable energy technology in the world between 2000 and 2011, driven by a tenfold drop in cost, but solar still only provides a tiny percentage of global electricity.

However, in a best case scenario the IEA estimates solar could provide a third of all global energy by 2060, all without climate-warming emissions. The future limit to solar power is unlikely to be cost, according the IEA. Solar power is already cheaper than the diesel generators used in many parts of the world to provide power and rooftop solar is competitive with grid electricity for business consumers in many places.

“By 2025, everybody will be able to produce and store power. And it will be green and cost competitive, ie, not more expensive or even cheaper than buying power from utilities,” said a report from banking giant UBS in August. It urged its financial clients to “join the revolution”. Germany currently has the most installed solar power, with twice as much as second placed Italy. China and the US – both major panel manufacturers – are next followed by Japan and Spain.

Analysts at Bloomberg New Energy Finance (BNEF) predict over 40% of all new energy generation between now and 2030 will be solar, with rooftop panels dominating. “A small-scale solar revolution will take place over the next 16 years thanks to increasingly attractive economics in both developed and developing countries,” they wrote in July.

In the biggest potential markets – the billion-people countries of China and India – BNEF expect solar power to match coal and gas prices by 2020. So rather than cost, the key to the large scale roll-out of solar will be addressing the unavoidable problem of nightime darkness and the currently limited ability to store electricity in many countries. As a result, most analysts believe solar power will need continued supportive policies from governments – such as putting a price on carbon emissions – for solar to play its potentially major role in meeting growing energy demands while at the same time tackling global warming.