As the cost of solar energy has plummeted in recent years alongside major improvements in technical efficiencies and manufacturing quality, many homeowners across the U.S. are starting to look at solar as a viable alternative energy solution. And as solar enters mainstream energy markets, the big question is, “how do solar panels work?” In this article, we’ll break down exactly how solar panels produce energy for your home and how pragmatic going solar really is.
Key takeaways: how do solar panels work?
- Solar cells are typically made from silicon, which is a semiconductor and can generate electricity
- This process is known as the “photovoltaic effect”
- See how solar panels can work for you with custom quotes on the EnergySage Marketplace
How do solar panels work? Step by step overview of the solar generation process
In a nutshell, a solar panel works and generates electricity when particles of sunlight knock electrons free from atoms, setting in motion a flow of electrons. This flow of electrons is electricity, and solar panels are designed to capture this flow, making it a usable electric current.
Solar power generation starts when solar panels absorb sunlight with photovoltaic cells, generating this direct current (DC) energy and then converting it to usable alternating current (AC) energy with the help of inverter technology. AC energy then flows through the home’s electrical panel and is distributed accordingly. The main steps for how solar panels work for your home are:
- Photovoltaic cells absorb the sun’s energy and convert it to DC electricity
- The solar inverter converts DC electricity from your solar modules to AC electricity, which is used by most home appliances
- Electricity flows through your home, powering electronic devices
- Excess electricity produced by solar panels is fed to the electric grid
How do solar panels generate electricity?
A standard solar panel (also known as a solar module) consists of a layer of silicon cells, a metal frame, a glass casing, and various wiring to allow current to flow from the silicon cells. Silicon (atomic #14 on the periodic table) is a nonmetal with conductive properties that allow it to absorb and convert sunlight into electricity. When light interacts with a silicon cell, it causes electrons to be set into motion, which initiates a flow of electric current. This is known as the “photovoltaic effect,” and it describes the general functionality of solar panel technology.
The science of generating electricity with solar panels all comes down to the photovoltaic effect. First discovered in 1839 by Edmond Becquerel, the photovoltaic effect can be generally thought of as a characteristic of certain materials (known as semiconductors) that allows them to generate an electric current when exposed to sunlight.
The photovoltaic process works through the following simplified steps:
- The silicon photovoltaic solar cell absorbs solar radiation
- When the sun’s rays interact with the silicon cell, electrons begin to move, creating a flow of electric current
- Wires capture and feed this direct current (DC) electricity to a solar inverter to be converted to alternating current (AC) electricity
The science of solar panels, in depth
Silicon solar cells, through the photovoltaic effect, absorb sunlight and generate flowing electricity. This process varies depending on the type of solar technology, but there are a few steps common across all solar photovoltaic cells.
First, light strikes a photovoltaic cell and is absorbed by the semiconducting material it is made from (usually silicon). This incoming light energy causes electrons in the silicon to be knocked loose, which will eventually become the solar electricity you can use in your home.
There are two layers of silicon used in photovoltaic cells, and each one is specially treated, or “doped”, to create an electric field, meaning one side has a net positive charge and one has a net negative charge. This electric field causes loose electrons to flow in one direction through the solar cell, generating an electrical current. The elements phosphorus and boron are commonly used to create these positive and negative sides to a photovoltaic cell.
Once an electrical current is generated by loose electrons, metal plates on the sides of each solar cell collect those electrons and transfer them to wires. At this point, electrons can flow as electricity through the wiring to a solar inverter and then throughout your home.
What about alternative solar technologies to photovoltaics?
We’ve been talking about photovoltaic solar, or PV, in this article, because it’s the most common type of solar energy generation, especially for homes and businesses. But there’s more out there, and they work in different ways than traditional photovoltaic solar panels. Two of the most common alternative solar options that work differently than PV panels are solar hot water and concentrated solar power.
Solar hot water
Solar hot water systems capture thermal energy from the sun and use it to heat water for your home. These systems are made of a few major components: collectors, a storage tank, a heat exchanger, a controller system, and a backup heater.
In a solar hot water system, there’s no movement of electrons. Instead, the panels transform sunlight into heat. The panels in a solar thermal system are known as “collectors,” and are typically installed on a rooftop. They collect energy very differently than traditional photovoltaic panels – instead of generating electricity, they generate heat. Sunlight passes through a collector’s glass covering and strikes a component called an absorber plate, which has a coating designed to capture solar energy and convert it to heat. This generated heat is transferred to a “transfer fluid” (either antifreeze or potable water) contained in small pipes in the plate.
Concentrated solar power
Concentrated solar power (also known as concentrating solar power or concentrating solar-thermal power) works in a similar way to solar hot water, in that it transforms sunlight into heat. CSP technology produces electricity by concentrating solar thermal energy using mirrors. At a CSP installation, mirrors reflect the sun to a focal point. At this focal point is an absorber or receiver that collects and stores heat energy.
CSP is most often used in utility-scale installations to help provide power to an electricity grid.
How does grid connection work with solar panels?
Though electricity generation with solar panels may make sense to most people, there’s still a lot of general confusion about how the grid factors into the home solar process. Any home that is connected to the electrical grid will have something called a utility meter that your energy provider uses to measure and supply power to your home. When you install solar panels on your roof or on a ground mount on your property, they are eventually connected to your home’s utility meter. The production of your solar system can actually be accessed and measured by this meter.
Most homeowners in the U.S. have access to net metering, a major solar incentive that significantly improves the economics of solar. If you have net metering, you can send power to the grid when your solar system is overproducing (like during the day in sunny summer months) in exchange for credits on your electric bill. Then, during hours of low electricity production (such as nighttime or overcast days), you can use your credits to draw extra energy from the grid and meet your household electricity demand. In a sense, net metering offers a free storage solution to property owners who go solar, making solar an all-in-one energy solution.
Additional important parts to solar panels
Aside from their silicon solar cells, a typical solar module includes a glass casing that offers durability and protection for the silicon PV cells. Under the glass exterior, the panel has a layer for insulation and a protective back sheet, which protects against heat dissipation and humidity inside the panel. This insulation is important because increases in temperature will lead to a decrease in efficiency, resulting in lower solar panel performance.
Solar panels have an anti-reflective coating that increases sunlight absorption and allows the silicon cells to receive maximum sunlight exposure. Silicon solar cells are generally manufactured in two cell formations: monocrystalline or polycrystalline. Monocrystalline cells are made up of a single silicon crystal, whereas polycrystalline cells are made up of fragments or shards of silicon. Mono formats provide more room for electrons to move around and thus offer a higher efficiency solar technology than polycrystalline, though they are typically more expensive.
Guarantee major savings with solar panels
If you want to start saving money on electricity, the first place to start is comparing solar panel system quotes. That’s where EnergySage can help: when you sign up for a free account on the EnergySage Marketplace, we provide you with custom quotes from installers in your area. So what are you waiting for – get started with your own clean energy journey with EnergySage today!