How Solar Panels Work
In an era when we are increasingly concerned about the environment, but our own pockets, too, seeking to make everything in our life more efficient, renewable energy sources are the number one choice we have when pursuing these ecological and economical goals. Today we will seek to find out how solar panels work, discovering new details and figures that give you an overall image.
A solar panel works by allowing photons, or particles of light, to knock electrons free from atoms, generating a flow of electricity. Solar panels actually comprise many, smaller units called photovoltaic cells – photovoltaic simply means they convert sunlight into electricity. Many cells linked together make up a solar panel. Silicon is what is known as a semi-conductor, meaning that it shares some of the properties of metals and some of those of an electrical insulator, making it a key ingredient in solar cells. Let’s take a closer look at what happens when the sun shines onto a solar cell.
Sunlight is composed of miniscule particles called photons, which radiate from the sun. As these hit the silicon atoms of the solar cell, they transfer their energy to loose electrons, knocking them clean off the atoms. The photons could be compared to the white ball in a game of pool, which passes on its energy to the coloured balls it strikes.
Photovoltaic cells need to establish an electric field. Much like a magnetic field, which occurs due to opposite poles, an electric field occurs when opposite charges are separated. To get this field, manufacturers “dope” silicon with other materials, giving each slice of the sandwich a positive or negative electrical charge.
Specifically, they seed phosphorous into the top layer of silicon, which adds extra electrons, with a negative charge, to that layer. Meanwhile, the bottom layer gets a dose of boron, which results in fewer electrons, or a positive charge. This all adds up to an electric field at the junction between the silicon layers. Then, when a photon of sunlight knocks an electron free, the electric field will push that electron out of the silicon junction.
A couple of other components of the cell turn these electrons into 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. There are other types of solar power technology — including solar thermal and concentrated solar power (CSP) — that operate in a different fashion than photovoltaic solar panels, but all harness the power of sunlight to either create electricity or to heat water or air.
Residential solar systems are typically sized from 3 to 8kW and end up costing between $15,000 and $40,000. The cost per watt (price inclusive of parts, labor, permitting fees, overhead, and profit) has decreased significantly over the last decade and is now between 6 and 8 ($/W) in many parts of the U.S. Generally, the bigger the system, the lower the cost per watt.
Sources: Livescience.com, Physics.org
