You may wonder how a solar panel actually creates energy – if so, you’re not alone! Though the idea might seem complex, the technology behind a solar panel, or module as it’s also called, is quite simple, and has been around for a long time. For your history review, solar cells (60 0r 72 make up a current panel) have been producing energy since the 1880’s!
Taking a look back to 1954, the solar cell, a sandwich of two structures made up of semi-conducting material (silicon, common today), came into production. At this time, the cost of solar energy was $286 per watt, nearly 300% greater than today’s rates. With an efficiency rate of only 4%, the cost was astronomical. This means that only .04 of the usable light that hit the cell would convert to energy. With today’s rates between 15-20% commonly, you can see how far the technology has developed (and how much the cost has decreased!).
But, back to our original question: how do solar cells actually work? Basically, a solar cell allows particles of light, also known as photons, to break free from atoms, which generates a flow of electricity. In other words, photovoltaic cells establish an electric field.
Similar to a magnet, electric fields need a positive and negative charge to separate. This is done with the solar cell ‘sandwich’, where the silicon is given a positive or negative charge. The top layer is given more electrons through added phosphorous, and thus a negative charge. The bottom layer has boron added, which gives it fewer electrons and a positive charge. This creates an electric field where the silicon layers meet, so when the photon of sunlight knocks an electron free, the electric field will push that electron out of the silicon junction.
To create usable power, metal conductive plates on the sides of the cell collect the electrons and transfer them to wires. At that point, the electrons can flow like any other source of electricity. Even in partially cloudy areas, such as the Pacific Northwest, solar can make viable sense. Direct sunlight is not needed to create energy, and often panels will perform well when they are cooler, such as in areas that aren’t always in direct sunlight and high heat.
Written By: Karry Yoerger is the Supply Solutions Service Center and Solar Energy Manager at North Coast Electric. He was a key member of the solar startup team at NCE in 2009. He has served as a Board member of OSEIA, (Oregon Solar Energy Industries Association) whose mission is to advocate for solar technologies and raise awareness of its potential to secure affordable, reliable, and clean energy for the future. Karry is a trainer at NCE for solar energy products, their application and project design. Karry will coordinate NABCEP CEU training at NCE in 2015.