Anyone with an interest in alternative sources of green energy has most likely asked themselves the question, How do solar panels work? These days, solar panels are popping up in more and more places. From small landscaping lights to calculators and from call boxes to large solar fields in the desert and even satellites. It's hard to go a whole day without seeing solar power in action. But how exactly do those panels turn the light from the sun into energy? This article will explain the basics of how solar panels function and will then refer you to more technical resources if you desire to learn more.
So How Do Solar Panels Work?
The complicated science of how solar panels convert sunlight into electricity is beyond the scope of this article, but it is possible to understand the general idea of solar power production without getting too technical.
Photons Into Electrons
The solar panels you see on a landscaping light or a calculator are made of photovoltaic cells. The purpose of these cells is to convert the light from the sun into electricity. Photovoltaic cells are typically comprised of silicon that acts like a semiconductor. When sunlight hits the silicon, the energy from the light is absorbed. Silicon is an excellent choice because of its atomic-level properties. In its natural state, silicon has the space for eight electrons in its outer band, but only carries four. Therefore, when two silicon atoms meet, each atom shares its four electrons with the other and a stable, strong connection is created. There is no positive or negative charge here, however, since each atom is receiving exactly what it needs.
For silicon to work as a material to produce energy, it must be combined with another element that has either a positive or negative charge. An element like phosphorus has five electrons, so when it is combined with silicon, the bond will have eight shared electrons with one free electron that is not needed by the silicon yet is still bonded to the phosphorus. This creates a negatively charged combination.
However, for an energy current to flow, there needs to be a positive charge. To accomplish this, silicon atoms are also combined with an element like boron that only has three electrons. Now the boron is completely bonded, but there is still a space in the silicon atom for another electron. In solar panels, this positively charged plate is put together like a sandwich with the negatively charged plate, and conductive wires are placed between them.
This is where the photons from the sun come into play. When the negatively charged plate in the solar panel is faced toward the sunlight, the photons from the sunlight blast away at the solar panels until they eventually knock the extra electron on the negative plate loose. The positive plate that has a space for the extra electron quickly gathers the freed electron up. As the photons from the sun keep breaking off electrons, an electric current is created. At this point, metal contacts are attached to each side of the photovoltaic cell so the current can be drawn off and used as electricity. Depending on the size of the photovoltaic cell and the electric fields built-in to the cell, the wattage of the cell will vary.
Limitations of Solar Power
Now that you have a basic idea of how solar panels work, you might wonder why solar panels aren't the primary source of power in the world. The problem is that it is still not a very efficient process for generating power. The amount of electricity created by solar panels is relatively low compared to the size of the panels. Plus, the angle of the solar panels is very important; if the panels are not facing the sun just right, the efficiency can drop considerably. Solar panels are getting better and better, but engineers are still searching for ways to make them more efficient, smaller and easier to maintain.