Scientists have developed a new kind of cell which could make solar energy cheaper than oil within 10 years.
The system uses organic materials such as carbon, oxygen and hydrogen that can be extracted from the air.
Professor Kwanghee Lee, of South Korea's Pusan National University, said in Wellington thatthe new system was not yet as efficient as present silicon-based systems of converting sunlight into energy.
"But to reach the current efficiency of inorganic solar cells took 50 years. Organic solar cells have only been known for five years so far. Within four or five years we have proved that they will work to this level, and they will be commercialised within 10 years."
His team at Pusan has discovered that organic solar cells can also work in reverse, transforming energy into light in the form of light-emitting diodes like those in cellphone screens.
In a few years, Dr Lee foresees solar-powered cellphones, using sunlight to charge the batteries. He is patenting the discovery and negotiating with a Korean cellphone manufacturer about using it.
The new system simply does what nature has done for millions of years through photosynthesis - transforms energy from the sun into leaves and other forms of organic matter.
"All energy on earth comes from the sun," he said. "So the best way to solve our energy problem may be to use solar energy efficiently and safely. Solar energy is quite safe, very clean, and there is no limitation on it."
Organic solar cells could be much bigger than silicon crystals, could be made at room temperature and would eventually cost less than a tenth of the present inorganic cells - making them cheaper than oil.
They could also be made in the form of a thin, transparent film which could fit over the windows of a building and provide enough energy to run the activities inside.
Cars could be coated with the material and could be charged up simply by being parked in the sun. If parked indoors, a car's battery could be charged up from solar energy collected on the building.
But Dr Lee said other forms of energy would still be needed for intensive industry.
