How Effective Are Solar Panels?

Most solar panels collect only about one-fifth of the available light, largely because of inefficient electrical circuitry, the materials they are made out of and their inflexibility. New flexible prototypes, called nantennas, can collect as much as 90 percent of available light, including light from wavelengths that currently are untapped.

More facts about solar energy:

• The amount of solar power in use increased by more than 150 times from 1985-2007, going from only about 20 megawatts to almost 3,000 megawatts.


• About 3,850,000 exajoules — an exajoule is 10¹⁸ joules — of solar energy are absorbed by the Earth every year. To put that in perspective, the United States uses only about 95 exajoules of energy in total a year.


• One of the earliest solar-powered houses was the Solar I, built by the Massachusetts Institute of Technology in 1939. Though not totally reliant on solar panels, the house was heated in the winter by solar power, and it sometimes used solar panels for air conditioning and power.