By taking this approach, cells are stacked so that as light passes through the cells, the lower solar cells convert the band of light that the higher cells can't - increasing the efficiency of the entire photovoltaic cell tremendously.
The Eco-Drive system works by way of a solar conversion panel under the watch dial that uses a photovoltaic process to capture and convert light into electrical energy, which is then transferred to a special energy cell for storage.
By 1958, Hoffman Electronics produced photovoltaic cells that were 9 percent efficient, and then the following year those cells were used to power Vanguard I, the first satellite to use PV technology for power.
While its share of meeting the nation's energy needs is currently small, the number of photovoltaic panel installations grew 40 percent in 2009, according to data from the Interstate Renewable Energy Council.
After his discovery, physicists soon discovered the photovoltaic effects of selenium, and in 1904 Einstein published a paper describing the photoelectric effect that later won him the Nobel prize in 1923.