solar panel generating electricity for a home

How do solar panels work? The science behind solar power generation

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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 renewable energy solution. And as solar enters mainstream energy markets, the big question is, “how do solar panels work?”.

In a nutshell, a solar panel generates electricity when particles of sunlight, or photons, knock electrons free from atoms, setting them in motion. This flow of electrons is electricity, and solar panels are designed to capture this flow, making it a usable electric current. This electric current is created by photovoltaic cells, and the components of those cells turn the electricity into usable power. 

In this article, we’ll break down exactly how solar panels produce renewable 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

Solar power generation starts when solar panels absorb photons, or particles of light, 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:

1. Photovoltaic cells absorb the sun’s energy and convert it to DC electricity

Photovoltaic cells are treated with phosphorus and boron, giving them positive and negative charges conducive to carrying an electric current.

2. The solar inverter converts DC electricity from your solar modules to AC electricity, which is used by most home appliances

DC electricity becomes AC output when an inverter switches the direction of the current rapidly enough that it becomes AC power. Inverters can also be equipped with transformers that regulate the voltage of DC and AC currents. 

3. Electricity flows through your home, powering electronic devices

Solar inverters transfer converted AC energy to your home’s electric box. From there, electricity is dispersed through your house by wires in the wall so that when your devices need to be plugged in, there is an electric current available.

4. Excess electricity produced by solar panels is fed to the electric grid

If you have a grid-tied solar system, energy runs both ways to and from the grid, and excess energy produced by your panels can actually make you money with a policy called net metering. Through net metering, you receive credits from the grid you are feeding your excess energy to, which makes your overall cost of electricity even cheaper. Learn more about the net metering policy in our article.

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 photons interact 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:

1. The silicon photovoltaic solar cell absorbs solar radiation

More specifically, the semiconductor, which is not as effective in conducting electricity than metal, hence “semi”, absorbs light energy. There are a few different types of semiconductors typically used in solar cells. Silicon is by far the most commonly used semiconductor, making up 95% of solar cells manufactured today. Cadmium-telluride and copper indium gallium diselenide are the two main semiconductor materials used in thin-film solar panel production.

2. When the sun’s rays interact with the silicon cell, electrons begin to move, creating a flow of electric current

The wavelength of the light that shines on the PV cell plays a role in the overall efficiency it possesses. 

3. Wires capture and feed this direct current (DC) electricity to a solar inverter to be converted to alternating current (AC) electricity

These wires are the grid-like lines you typically see on solar cells. The efficiency of a solar cell refers to how much electricity is picked up by these wires compared to the amount of sunlight that shines on the cells. 

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). These incoming photons cause 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 utility company 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’s renewable energy 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, almost like a battery, 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.

Frequently asked questions related to how solar panels work 

Learning more about how solar panels work can be confusing at times, which is why making it simple and digestible is key. Now that you know more about how solar panels generate electricity and the science behind it, check out a few other questions that homeowners commonly ask: 

What are the two main disadvantages to solar energy?

The two main disadvantages of solar energy are its high upfront costs and intermittency. While investing in renewable energy pays off in the long run, this technology is typically more expensive than traditional energy generators when it comes to installation. Luckily, there are financial incentives, such as tax credits and rebates, available to help alleviate the initial burden. Additionally, intermittency can be an issue— renewable energy resources aren’t available 24/7, year-round. For instance, solar panels produce less electricity at night and on overcast days. There may be unpredictable weather patterns that impact the efficiency of solar panels, but you can consider battery options as a backup. Read this article to see if you should get storage.

Can you run your whole house on solar power? 

Yes, you can generate enough electricity for your entire house using solar power. The key is making sure your solar panels are operating at maximum efficiency by choosing the right type of panel, installer, and the best angle for your home and your needs. However, although a solar panel system can offset all of your energy usage, it’s not realistic to expect that level of production every day due to intermittency. Installing storage will help if you don’t want to rely on the grid when the sun isn’t shining. 

Do you still have an electric bill with solar panels?

Yes, if you’re connected to the grid, you’ll still receive an electric bill with solar panels –  but it’s possible that you won’t owe anything. However, if your solar panels are not producing enough energy to meet your needs, or if you’ve increased your energy consumption since installation, you’ll likely still owe some money to your utility. If you want to rely completely on solar energy, you will need to add solar battery backup to pair with your solar panels. 

Guarantee major savings with solar panels

If you want to start saving money on electricity and invest in renewable energy, 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!

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28 thoughts on “How do solar panels work? The science behind solar power generation

  1. AMANDA HOng

    I bought the house had a solar panels free and clear. electric bill came first month is 17$ which is we didnt use bc the house was empty for construction. Is that normal if I stay there for and pay like 50$/m or 80$/m? if so that is alot if we have Solar right? The solar panels have been there for 16 years. THnks

    Reply
    1. Kevin

      As a solar panel user, former installer, and home energy auditor, I may be able to offer some insight. Your utility company will probably charge you a monthly administrative fee for having access to electricity. In our state, this is true whether you have solar or not and it’s the same price, $15. So even if I don’t use any utility electricity, I have to pay $15 a month. Some utilities may charge solar home owners a higher monthly administrative fee. Now, just because you have solar, doesn’t mean you won’t have an electric bill. It depends on so many factors; size of the array, efficiency, array orientation, wattage produced per panel, shadowing, time of year, where you live, how much you use, how efficient your home is, etc. Most homes don’t have enough roof top for panels to cover their electricity use their entire year, but you can get close. The 30 panels on my roof completely cover my electricity cost 2-3 months a year. Solar is important but you also need to make your house the most efficient it can be by air-sealing it first and then adding insulation. Replacing your windows is typically the last thing you should do to save energy in your house unless you have single pane glass. If replacing windows, purchase those that are Energy Star rated. The air leaks in your ENTIRE home are what cost you money. An efficient home still has 4.5 -6.5 ACH (air changes per hour). Yes, the air in your home is being replaced 4.5 to 6.5 times per hour due to air pressure and thermal dynamics. One that hasn’t been air-sealed has 15 – 25 ACH! You keep paying to condition the air coming into your home and that’s why your utility bills are so high! You need to address the air leaks in your home to get the most out of your solar solution, but do both. You can even do solar first, but the real gains come when you fix the box you call your home. Get a full energy audit from an experienced auditor.

      Reply

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