Solar energy has held a place in human history as early as the 7th century B.C. The first modern-day solar panel made its debut in 1954. After WWII, scientists at Bell Labs were able to develop a solar panel that could power electrical equipment at the telephone company. Their panel was 4% efficient and continued to work 50 years later.
Solar panels produce energy using photovoltaics. Solar panels are made up of semi-conductive materials that, when exposed to sunlight, generate an electric current. These materials comprise the photovoltaic cell (PV). When the sun's rays come in contact with a PV cell, photons, or light particles, free electrons from atoms within the cell and generate electricity. Multiple PV cells comprise one solar panel. Some solar cells can now reach efficiencies above 30% and other solar technologies are being produced in different applications like Solar City’s solar roof shingles. These advancements mean that solar panels will become more applicable to multiple uses, be more cost effective, and have more reliability.
Solar panel productivity is affected by the amount of incoming sunlight as well as temperature. Solar panels work most effectively in direct sunlight but they can also produce electricity using indirect sunlight or when it’s cloudy or raining.
Due to the nature of the equipment, solar panels are most effective in cooler conditions. In some cases, even areas with frequent cloud cover have been shown to be ideal for solar energy production because of the cooler temperatures. A solar study between Sacramento and San Francisco found that foggy San Francisco produced slightly more solar energy in one year than sunny Sacramento did.