For 13-year-old Jia Quan, a middle school student in Beijing, his only impression of solar energy in the past was that it could be converted into electricity and stored in a battery. Some road lamps somewhere in Beijing were the only kind of application of solar energy he encountered.

It amazed him that solar energy could do much more than he ever expected. The teenager learned of this potential as he listened to a report on solar energy utilization presented by Signe Antvorskov, an engineer from Denmark working on household energy efficiency. According to Antvorskov, who appeared at the International Solar Energy Society's Solar World Congress in Beijing, held between September 18-21, solar cells can help indoor heating, ventilation, and even cooling.

In the house pictures she displayed, the roof shingles are coated with photovoltaic cells made of amorphous silicon and look much like ordinary roofing shingles. The electricity generated from the roof can basically satisfy a household's daily need.