Solar Energy: What, Why, and How
In 2021, the United States "consumed 100.53 quadrillion BTUs (British Thermal Units) worth of energy, with about 79% coming from fossil fuels" (ENERGY). With that said, applying clean energy research is extremely important if we aim to combat the global climate crisis. One way many individuals can take part is by using solar panels/cells to power their homes, but how do they work, and to what efficiency?
As one might infer, solar panels utilize the radiation from the sun to create usable energy. Photovoltaic cells do the actual work. If we break the name down, photo translates to light, and voltaic means electricity, which means that these cells convert light to electricity. These cells can produce electricity from light due to materials called semiconductors.
An example of a semiconductor is Silicon. When photons hit the material, "a certain portion of it is absorbed within the semiconductor material. This means that the energy of the absorbed light is transferred to the semiconductor. The energy knocks electrons loose, allowing them to flow freely" (Toothman & Aldous). By sticking metal contacts on either end of the PV cell, a current is able to be drawn to power lights, refrigerators, electric stoves, etc.
Diving a little deeper into how we can harness the sun's energy, an atom of silicon has 14 electrons, which are arranged in separate shells. The first two are filled, but the third is looking to be filled in, which "will share electrons with four nearby atoms. It's like each atom holds hand with its neighbors" (Toothman & Aldous). Once heat/energy is added to the silicon, a few electrons will break free of their bonds and begin to move around, looking for a hole to fall into. The hole is a spot where another electron had previously broken free. Once the hole is filled, it allows electrical current to be conducted.
Pure silicon, however, is a poor electrical conductor, so other atoms must be added to benefit from the above process. Atoms such as phosphorus are added, making the pure silicon, impure. Usually, impurity is thought of as a bad thing, but in this case, it’s a necessity as phosphorus has five electrons. Purposely adding impurities is called doping. When there is a widespread presence of free electrons and not enough holes, “the resulting silicon is called N-type (“n” for negative) (Toothman & Aldous).
The other part of a solar cell, P-type (“p” for positive), has “free openings and carries the opposite charge” (Toothman & Aldous), which is made possible by doping the cell with boron. Why boron? Because it only has three electrons instead of four, it allows for more holes than electrons to occupy.
With two sides to the solar cell, N-type and P-type, they can be combined to form what’s called a junction. This is an interface or boundary between the two types, which is crucial for creating an electric field. This field is created when the “free electrons on the N side see all the openings on the P side, and there’s a mad rush to fill them” (Toothman & Aldous). If all the electrons filled all the holes, the panel wouldn’t work as it should. The electric field “acts as a diode, allowing (and even pushing) electrons to flow from the P side to the N side, but not the other way around” (Toothman & Aldous). The flow of these electrons is what creates a current, and the cell’s electric field results in voltage. These two electrical quantities are what give us power or wattage.
So how much energy can a solar panel produce? On average, a single solar panel can “produce about 2 kilowatt-hours of electricity daily” (Lane). Combine that with 15 others producing an average of 30 kWh of solar energy, it’s enough to “cover most, if not all, of a typical home’s energy consumption” (Lane)
What amount of power does a typical house require? “According to the United States Energy Information Administration, the average American household consumed…” an average of 29 kWh per day (Rkha). A kilowatt-hour is a unit of energy, which measures the amount of energy used over a period of time. So, to power a house that consumes 29 kWh, you need to provide 29 kWh of energy.
Now that we have a good idea about how a solar panel works and the amount of energy needed to power a home, what are the incentives? The biggest for many is cost. “The average cost-per-watt across the U.S. is around $2.86/W before incentives” (Walker & Aggarwal). The average cost of an 11-kWh panel would cost you about $31,460 or $18,172 after federal tax for installation. With that said, depending on your solar panel setup or the amount of kWh it can produce, and how much your house consumes, your entire energy bill would be covered.
Another incentive is lowering your carbon footprint. Many homes run off non-renewable energy sources such as coal or fossil fuels. Of course, depending on your location. Solar energy is a renewable, clean energy source. While many may criticize and say, “Well the panels themselves require a manufacturing process that produces waste in the process and requires the Earth to be mined, so does coal, so does fossil fuels. The main difference is the extent, compared to traditional means, that the production of these solar cells is harmful.
Studies have shown that the lifecycle greenhouse gas emissions of solar panels “are much smaller than the remaining emissions from existing fossil power plants before they can finally be decommissioned” (Evans). It’s also worth noting that the environmental impact of fossil fuel extraction, transportation, and combustion is much larger than solar cell production. The air and water pollution caused by fossil fuels most definitely outweighs the production of solar panels and how they provide energy.
Pivoting back to providing your house with energy from the sun, let’s say you have been producing more energy than your house needs. This could be due to having more solar panels than needed. What do you do with it? One option included storing it. This usually comes at an additional charge for a solar company to install. Essentially, these batteries can be “filled” with the leftover energy collected by the sun that your house didn’t use. This comes in handy when your power goes out due to a storm, allowing you to continue to power your house. Another solution is to sell it back to the energy company.
Whether you want to cut back on your carbon output or save money on electricity, installing solar panels is a great option. Because of their ability to take in the radiation from the sun and convert it to energy, it makes solar energy clean energy. Next time you see solar panels, instead of thinking how ugly they may look, think about the benefits that they are providing not just for the homeowner, but for yourself.
Works Cited
Evans, Simon. “Solar, Wind and Nuclear Have ‘amazingly Low’ Carbon Footprints, Study Finds.” Carbon Brief, 8 Dec. 2017, www.carbonbrief.org/solar-wind-nuclear-amazingly-low-carbon-footprints/.
Lane, Catherine. “How Much Energy Does a Solar Panel Produce?” How Much Energy Does A Solar Panel Produce?, Solar Reviews, 1 Dec. 1969, www.solarreviews.com/blog/how-much-electricity-does-a-solar-panel-produce#:~:text=On%20average%2C%20a%20solar%20panel%20will%20generate%20about%202%20kWh,TV%20for%2024%20straight%20hours!
Rkha, Victor. “What Is the Average Kwh per Day in American Households?” Agway Energy Services, 5 July 2023, www.agwayenergy.com/blog/average-kwh-per-day/#:~:text=Contact%20Us,considerably%20from%20state%20to%20state.
Toothman, Jessika, and Scott Aldous. How Solar Cells Work, wcpssccsi.pbworks.com/w/file/fetch/67747809/solar%20cells-11162012150624.pdf. Accessed 26 June 2024.
“US Energy Statistics and Data Trends: Renewables, Fossil Fuels, Electricity Costs and More.” USAFacts, 3 Feb. 2023, usafacts.org/topics/energy/.
Walker, Emily, and Vikra Aggarwal. “Solar Panel Cost in 2024: It May Be Lower than You Think.” EnergySage, www.energysage.com/local-data/solar-panel-cost/. Accessed 25 June 2024.
