You see them nowadays dotting roofs in neighborhoods, in clusters on roadside fields, atop vast industrial concepts when you’re landing at an airport. Solar panels are much more common today than they were even just five years ago. What’s going on with this new technology that can convert sunlight into energy?
New? Wait. The idea for solar panels emerged nearly 200 years ago when a scientist named Edmond Becquerel saw how certain materials sparked when hit by sunlight. This began our understanding of the photovoltaic (PV) effect, which, at the turn of the 20th century, could be captured by cells made of selenium. “Photo” means light, and “voltaic” means sun. By the 1950s, four percent of sunlight’s energy was being converted directly to electricity through PVs by scientists at Bell Labs.
We’ve been hoping for decades that solar can replace fossil fuels to heat our homes and businesses. There’s so much free electricity for the taking from the sun! On a day with clear blue skies, the sun’s rays give off approximately 1,000 watts of energy per square meter of the planet’s surface. In a single hour, the sun transmits more energy to the earth’s surface than the world uses in a year.
If only we could capture all that wonderful sunshine and power our homes, businesses, and appliances! Unfortunately, we still have a gap in research to make the hope for 100% solar power a reality.
How does a PV cell work?
Electricity is the movement of electrons. Electrons create charge, which can then be put to use for power. Under the sun, a PV cell acts as a photosensitive diode. A diode is a semiconductor device that permits current to flow readily in one direction but restricts it from the opposite flow. Current is the movement of electricity along a conductor. With polarity, diodes have an anode or positive lead and a cathode or negative lead. Usually, flow occurs only with positive voltage to the anode. The photosensitive diode instantaneously converts light into electricity.
A PV cell has two layers. The top layer is made up of phosphorus-diffused silicon, and this layer carries free electrons. Free electrons are non-anchored particles with negative charges. The bottom layer is thick and boron doped. Doping is a process of adding impurities to intrinsic semiconductors to alter their properties. Boron is the p-type dopant of choice for silicon integrated circuit production because it diffuses at a rate that makes junction depths easily controllable. The term p-type refers to the positive charge of the hole. Since this bottom boron layer contains holes, or absences of free-moving electrons, the two layers have an explicit electronic imbalance.
Once the cell is exposed to sunlight, the fun begins. Photons inundate and penetrate the cell, activating electrons. The electrons, in turn, get disengaged within both silicon layers. All of a sudden, the free electrons on one side see openings on the other side, and there’s a furious rush to fill them. Some of the electrons from the bottom layer shoot to the cell’s upper section, stream into the metal contacts as electricity, and circulate throughout. A closed loop or circuit results when the electrons surge back into the cell through the solid contact layer at the bottom.
From Cell to Inverter: Powering Buildings with Solar Energy
A solar panel is a solar cell that is usually comprised of multiple layers of silicon-based semiconductor wafers. Dozens of these cells are grouped into solar modules. A module is a group of cells that are connected electrically and bundled into a frame that’s called a solar panel.
When current exits the solar module, it moves through a wire conduit that leads to an inverter. Like it sounds, the device inverts direct current, with specific and fixed current and voltage, into alternating current (AC), or current that oscillates in direction and voltage. The inverter transforms the power into AC because that’s the current used by appliances in U.S. homes and utility electricity distribution grids.
The panels are mounted on rooftops in configurations that try to gather every possible minute of direct sunlight exposure.
From the inverter, the solar-generated power spreads throughout the circuitry of a building and then outward to the electrical grid. Integrated electricity from solar panels to the grid is important, as most people need to augment solar generation. Technology has introduced smart inverters, which are increasingly providing data monitoring for solar installation performance and other grid integration services. Sometimes a decentralized, or independent, solar power system can be self-contained, so that it does not need to connect to the grid. A decentralized system requires batteries to store power for times when sunlight is unavailable for conversion, like cloudy days, snow-covered roofs, and nighttime. Like much in the world of solar, battery storage capacity changes constantly, with each year seeing more capacity for less costs.
So Many Ways to Use Solar Energy to Power our Lives
The compass direction of a roof can make or break a structure’s feasibility for solar panels. But if your roof faces north, or is shadowed by large, old trees, or is too small in size to be a viable solar rood space, don’t despair. There are many innovative options to capture solar energy coming on to the market everyday. Here are just a few.
- Solar Awning: A company called Swedish Solar has created a series of four motorized, remote-controlled panels that hang over windows and are designed to maximize solar output. They can even serve as storm shutters!
- Solar Powered Tent: The tent, which was designed as part of young inventors grant project, consists of insulated fabric, solar panels, safety locking system, and UV sanitizing system.
- Solar/ Motion Fabric: The Georgia Tech School of Materials Science and Engineering has combined two types of electricity generation into one textile so that olar cells fabricated from lightweight polymer fibers into micro-cables are then woven via a shuttle-flying process.
The sun is the source of all life on planet earth. It is a renewable, absolutely pollution-less source of energy for every powered structure. When you think of it, burning fossil fuels in a central plant is a very 19th century mindset. Our hope is that, soon, very soon, we will be able to fully harness the potential and efficacy of the sun and convert it into electricity through solar panels and solar roof tiles. Then we’d remove one significant source of harmful emissions into the environment.
Solar power is now the least expensive source of electricity on average in 58 emerging economies around the world, according to Bloomberg New Energy Finance. Now it’s just a matter of patience for all of us while researchers investigate how to increase the capacity of solar panels and battery storage.