Solar panels convert the sun’s energy into usable electricity. At a high level, solar cells absorb incoming sunlight to produce an electrical current via the “photovoltaic effect.” This electrical current is captured by plates and wires and turned into a usable energy current that is sent to your home and appliances. In this article, we’ll go over how solar panels generate renewable energy for your home.
What exactly is solar energy?
Photons that reach your solar cells and generate an electric current are emitted by the sun. Solar energy is produced by the continuous nuclear fusion reactions that occur deep within the sun. Nuclear fusion occurs in the sun when protons (which are essentially the same as hydrogen atoms) collide and fuse to create helium under extreme temperature and pressure. This process emits a massive amount of energy (plus more protons), and it occurs constantly in the core of the sun, producing over 500 million tons of hydrogen atoms every second.
The end result? Our sun is approximately seven million degrees Fahrenheit in temperature and constantly emits massive amounts of energy in the form of electromagnetic radiation (EMR). EMR comes in many forms, and the sun generates all of them, which are carried to Earth in the form of photons.
Solar cells and the photovoltaic effect: the science of how solar panels work
In a nutshell, a solar panel generates electricity when photons, or particles of sunlight, knock electrons free from atoms, causing them to move. This flow of electrons is known as electricity, and solar panels are designed to capture it and convert it to usable electric current. The photovoltaic effect is the fundamental chemical and physical process underlying the vast majority of solar technology.
Explanation of the photovoltaic effect
The photovoltaic effect is at the heart of the science of generating electricity with solar panels. The photovoltaic effect, discovered by Edmond Becquerel in 1839, is a property of certain materials (known as semiconductors) that allows them to generate an electric current when exposed to sunlight.
The photovoltaic effect operates in the following steps:
- Sunlight strikes the solar cells, energizing electrons and setting them in motion.
- An electrical current is created when electrons flow out of the junction between cell layers.
- Metal plates and wires capture electron flow and generate electricity.
The process of generating solar electricity begins with solar cells, which are the individual components of a larger solar panel. Solar cells are typically made of silicon (atomic number 14 on the periodic table). Silicon is a nonmetal semiconductor that can absorb and convert sunlight into electricity; silicon is also used in nearly every computer on the planet. There are several types of semiconductors commonly used in solar cells, with silicon being by far the most common, accounting for 95% of all solar cells manufactured today. The two main semiconductor materials used in thin-film solar panel production are cadmium-telluride and copper indium gallium diselenide.
In photovoltaic cells, two layers of silicon are used, and each one is specially treated, or “doped,” to create an electric field at the junction between the layers. This electric field causes free electrons to flow through the solar cell and out of the silicon junction, resulting in the generation of an electrical current. To create the positive and negative sides of a photovoltaic cell, phosphorus and boron are commonly used as positive and negative doping agents, respectively.
The electrons pushed out by the electric field are collected by metal plates on the sides of each solar cell and transferred to connecting wires. Electrons flow as electricity through the wiring to a solar inverter and then throughout your home at this point.
Solar cell alternatives to silicon
While silicon is the most common semiconductor used in solar panels around the world, there are other options used in some new and emerging solar products.
Thin-film solar cells – Thin-film solar cells are a type of solar cell that is made of lightweight and/or flexible materials. Thin-film solar cells are classified into four chemical types: Cadmium Telluride (CdTe), Amorphous Silicon (a-Si), Copper Indium Gallium Selenide (CIGS), and Gallium Arsenide (GaAs). The light-absorbing layers in these cells are 350 times smaller than those in silicon cells, thus the term “thin-film.”
Organic solar cells – Organic solar cells are a subset of thin-film solar cells that rely on carbon-based materials as a semiconductor. These organic photovoltaics (OPV) are made by dissolving organic compounds in ink and printing them onto thin plastics. They are also known as “plastic solar cells” or “polymer solar cells.”
Perovskite solar cells – Perovskite solar cells are a type of thin-film solar cell that is made of perovskites, which are man-made materials with a unique crystallographic structure that allows them to convert photons of light into usable electricity. Perovskite cells are created using “solution processing,” the same method used to print newspapers.
Other important solar panel components
Aside from the solar cells, a typical solar module contains the following components:
The glass casing of the panels provides durability and protection for the silicon PV cells. Solar panels have an insulation layer and a back sheet beneath the glass exterior to protect against heat dissipation and humidity inside the panel. This insulation is critical because temperature increases reduce efficiency, resulting in lower solar panel performance. Solar panels have an anti-reflective coating that increases sunlight absorption and exposes the cells to the maximum amount of sunlight.
When it comes to silicon solar cells, there are two cell formations that are commonly used: monocrystalline and polycrystalline. Monocrystalline cells are composed of a single silicon crystal, whereas polycrystalline cells are composed of silicon fragments. Monocrystalline formats allow for more electron movement and thus provide a higher efficiency solar technology than polycrystalline formats, though they are typically more expensive.
What is the process by which solar panels generate electricity for your home?
The first step in a solar panel’s operation is to generate an electric current, but the process does not end there. The following is how solar panel systems generate usable electricity for your home:
- Photovoltaic cells absorb solar energy and convert it to direct current electricity.
As previously stated, the solar cells that comprise each solar panel do the majority of the heavy lifting when it comes to generating electricity. Your solar panels generate an electrical current due to the photovoltaic effect.
- Solar inverters convert direct current (DC) electricity from your solar modules to alternating current (AC), which is used by most home appliances.
When DC electricity passes through your solar inverter, it is converted to AC electricity. Transformers that regulate the voltage of DC and AC currents can also be installed in inverters.
- Electricity flows through your house, supplying power to electronic devices.
Solar inverters deliver the converted alternating current energy to your home’s electrical panel. From there, electricity is distributed throughout your home to all of your outlets, ensuring that when you plug in your devices, there is a usable electric current available.
- Excess electricity generated by solar panels is fed into the power grid.
If you have a grid-connected solar system, electricity can flow both to and from the power grid, and excess energy generated by your panels can actually make you money. Net metering is a policy that allows you to receive credits from the power grid when you send electricity back to it, lowering your overall electricity costs. Learn more about the policy of net metering.
What about solar technologies other than photovoltaics?
In this article, we’ve focused on photovoltaic solar, or PV, because it’s the most common type of solar energy generation, particularly for homes and businesses. But there are other options, and they work differently than traditional photovoltaic solar panels. Solar hot water and concentrated solar power are two of the most common alternative solar options that work differently than PV panels.
Solar water heating
Solar hot water systems collect solar thermal energy and use it to heat water for your home. Collectors, a storage tank, a heat exchanger, a controller system, and a backup heater are the major components of these systems.
There is no electron movement in a solar hot water system. Rather, the panels convert sunlight into heat. A solar thermal system’s panels, known as “collectors,” are typically installed on a rooftop. They collect energy in a very different way than traditional photovoltaic panels, generating heat rather than electricity. Sunlight passes through the glass covering of a collector and strikes an absorber plate, which has a coating designed to capture solar energy and convert it to heat. This heat is transferred to a “transfer fluid” (antifreeze or potable water) contained in small pipes within the plate.
Solar concentrating power
Concentrated solar power (also known as concentrating solar power or concentrating solar-thermal power) converts sunlight into heat in the same way that solar hot water does. CSP technology generates electricity by concentrating solar thermal energy through the use of mirrors. Mirrors in a CSP installation reflect the sun to a focal point. An absorber or receiver collects and stores heat energy at this focal point.
CSP is most commonly used in utility-scale installations to help power a power grid.
Commonly asked questions about how solar panels work
Learning more about how solar panels work can be difficult at times, which is why keeping it simple and easy to understand is essential. Now that you understand how solar panels generate electricity and the science behind it, consider the following questions that homeowners frequently ask:
What are the two main drawbacks of solar energy?
Solar energy has two major drawbacks: high upfront costs and intermittent power. While investing in renewable energy pays off in the long run, this technology is typically more expensive to install than traditional energy generators. Fortunately, there are financial incentives available, such as tax credits and rebates, to help alleviate the initial burden.
Furthermore, intermittency can be an issue because renewable energy resources are not available 24 hours a day, 365 days a year. Solar panels, for example, produce less electricity at night and on cloudy days. Unpredictable weather patterns may reduce the efficiency of solar panels, but battery options can be considered as a backup. Read on to find out if you should get storage.
Can you power your entire house with solar panels?
Yes, you can use solar power to generate enough electricity to power your entire house. The key is to ensure that your solar panels are operating at peak efficiency by selecting the right type of panel, installer, and angle for your home and needs. However, while a solar panel system can offset 100% of your energy consumption, it is unrealistic to expect that level of output every day due to intermittency. If you don’t want to rely on the grid when the sun isn’t shining, consider installing storage.
Do you still have an electric bill after installing solar panels?
Yes, if you’re connected to the grid, you’ll still get an electric bill with solar panels, but you might not owe anything. However, if your solar panels are not producing enough energy to meet your needs, or if your energy consumption has increased since installation, you will most likely still owe money to your utility. If you want to rely entirely on solar energy, you’ll need to pair your solar panels with a solar battery backup system.
Do solar panels function at night?
While some electricity can be generated at night from other light sources, the output is very low because solar panels’ cells require sunlight. When solar panels are combined with solar battery storage, energy is stored throughout the day for use in the evenings and even on cloudy days when solar panels are unable to benefit fully from a sunny day.
How do solar panels on a house work?
After determining the number of panels required to power a home, panels are mounted to a south-facing rooftop and angled to maximize the sun’s energy. These panels then absorb sunlight and convert it into electricity, as well as storing energy for cloudy days or at night for homeowners who choose to have a solar battery.
Solar panels ensure significant cost savings
If you want to start saving money on electricity and investing in renewable energy, compare solar panel system quotes first. So, what are you waiting for? Begin your clean energy journey with Accord Electrical & Solar today!