'At the floodgates'

DW: What's the potential for solar energy to prevent a climate disaster?

Eicke Weber: Solar energy, together with wind power, can potentially tackle the task of transforming the global energy system, thereby averting the worst effects of a climate disaster. But we have to act fast and take a courageous approach.

At the moment, we release between 30 to 35 billion tons of carbon dioxide (CO2) per year. The earth can still take about 700 billion tons until the dangerous two degree Celsius global increase is reached. This makes it incredibly important for us to begin right away. The good thing is that it's starting to become economically worthwhile - solar energy has gotten so cheap that we can generate it for about half the price of energy from diesel oil. And it's becoming competitive with all other fossil fuels.

So, can we rely on the markets to deal with the problem of climate change?

No. The transition to renewable energy is cutting into conventional energy producers' business. We've been experiencing this really unbelievable campaign in Germany and globally over the past year and a half that has been trying to systematically undermine the climate issue. We have to be clear: the transition to a new energy system has of course winners, but it has losers as well. And the losers are reluctant to have their privileges taken from them.

What's the significance of solar energy becoming cheaper?

The technology behind crystalline silicon solar cells has profited from extensive developments in the multi-billion-dollar microelectronics industry. About 20 years ago, a kilowatt of solar energy cost about 50 euro cents ($0.69) to produce, today in Germany it's about 10 euro cents - while in sunny regions it's between 5 and 8 euro cents. So worldwide, we're totally competitive with, and often even cheaper than, fossil fuels. Many countries are now able to break their dependency on the import of fossil fuels, and we can even generate electricity in our own homes.

What sort of developments are occurring at the moment in solar technology?

A very exciting development involves highly efficient solar cells with lens technology, or so-called concentrator photovoltaics (CPV). This new technology is just getting established on the market, and has a growth rate exceeding several hundred percent per year. It's already competitive, but still has great potential to become even cheaper. In the San Diego area, where there's a factory producing these types of cells, a 300-megawatt solar plant is being planned.

The solar boom is spreading from Germany and Europe. What's the global scenario?

We're at a floodgate where the doors are being opened. The first water is trickling through the cracks, but we won't experience the main rush for a few years still. This year, we've seen an increase of about 20 percent, and are expecting construction of new solar plants with about 37 gigawatts (GW) capacity. We're seeing the strongest growth in China, which this year overtook Germany as the world's largest photovoltaic market - it is expected to install around 9 new GW in 2013, compared with Germany's 3.5 GW.

We're seeing this development around the world. Some of the more interesting market situations are playing out in Saudi Arabia and the United Arab Emirates, which are preferring to export their oil rather than use it to generate electricity, and are instead building their own solar plants. Then there's South America, where Brazil and Chile are becoming very active. India is also interested in furthering its solar.

In addition to that, rooftop solar energy is now becoming competitively priced worldwide. In some cases it's even better value than conventional electricity. This is creating a fast-growing market. I'm expecting that modules with 100 GW capacity will be sold worldwide by 2020, and 300 GW modules will be available by 2025. By 2050, solar energy should cover at least 10 percent of the global energy demand.

But 10 percent won't be enough to protect the climate.

That 10 percent figure is a minimum. Personally, I think it's possible to have a 50 percent proportion of solar by 2050.

As a leading solar expert and global traveller, how do people around the world respond to your advice?

It's a very interesting situation. Practically all the politicians agree that climate is a serious problem and yes, we have to do something, we need an energy transition. But there's a huge gap between their public declarations and the detailed negotiations they engage in. Lobbies and other special interests creep into the negotiations. There are only a few politicians who really follow through on their promises on solar issues.

Eicke Weber directs the Fraunhofer Institute for Solar Energy Systems in Freiburg, Germany. The institute, founded in 1981, has about 1,300 staff and is the largest solar research institute in Europe.