Solar cells inch up in efficiency

Kyocera today said that it has achieved a new world record of 18.5% energy conversion efficiency with a 15 cm x 15 cm (5.9" x 5.9") multi-crystalline silicon solar cell. According to the company, the new results exceeds prior records, which were set by the company, including 14.5% in 1989, 17.1% in 1996, and 17.7% in 2004.

Energy conversion efficiency in solar cells refers to a photoelectric effect, also known as photovoltaics, that was discovered by Alexander Becquerel in 1839. First devices hat converted sunlight into energy were built in 1883 from Selenium wafers and became a common sigh in photographic exposure meters. The concept of eh actual solar cell was born in the 1950s.

Today, there are three basic silicon materials that are used as foundation of solar cells - amorphous silicon, multi-crystalline silicon an mono-crystalline silicon - with the latter being the currently most efficient variant in mass production: Efficiency rates are typically between 14 an 17%. The fact that many photons do not carry enough energy to be converted and a substantial part of photons is transformed into heat rater than electrical energy, gives the efficiency of solar cells a natural border, which is currently believed to be around 28% on the high end.

This circumstance requires rather large solar cell installations to have any impact on any major application. For example, roof-sized solar cell installations on average U.S. single-family homes currently reach outputs of between 1.5 kW and 6 kW can cost more than $30,000. But even at that size, the power output would only be a contributor to the energy needs of a household, especially when devices such as an air conditioner come into play.