The efficiency of solar power, or more specifically a solar panel, depends on the materials used to make each solar cell. A solar cell is that portion of a solar panel in which sunlight is collected and converted to solar electricity. The materials within each cell that perform this valuable duty are called semiconductors. The efficiency of a solar cell – and of solar power – is measured as the percentage of the total sunlight striking the cell that is converted into electricity by the cell.
In conventional solar panels, which you’ll see on 90 percent of rooftops today, crystalline silicon is the semiconductor of choice. Silicon solar panels hold the highest consistent conversion efficiencies of solar panels in use today. They convert on average between 15 and 20 percent of the light that hits them.
Thin-film solar panels are considered the wave of the future. They cost much less to manufacture than crystalline silicon panels, but as of yet cannot equal silicon in conversion efficiency. Cadmium telluride (CdTe) and cadmium-indium-gallium-selenide (CIGS) solar panels are the current champions of thin-film solar technologies, averaging around 11 percent efficiency. Most thin-film solar cells reside in the 4-10 percent range.
Solar power is still a relatively young technology. Scientists and researchers believe they can create solar cells that will reach 30-40 percent efficiency and beyond in the not-too-distant future.