How Solar Panels Work: Solar Power Science Explained

By: Karsten Neumeister 

We’d guess everyone reading this knows the basics of how solar panels work: they convert sunlight into electricity. But are you curious to learn more about the science behind the fastest-growing energy source in the U.S.?

A record number of homeowners are going solar to help lessen their dependence on traditional utility companies, slash monthly electric bills and reduce the environmental impact associated with fossil fuels with the help of reliable solar companies. Understanding how this form of renewable energy works empowers home and business owners to make an educated decision about whether to switch to solar power.

Let’s dive into the science of solar.

How Do Solar Panels Work?

It all starts with what’s called the photovoltaic effect: the ability of select matter to generate an electric current when exposed to sunlight. In 1839, the French physicist Edmond Becquerel (at only 19 years of age) first observed the photovoltaic effect by immersing two plates of gold in a conducting solution and exposing them to sunlight. This discovery sparked a great deal of interest, research and development. Fast forward just under 200 years, and we have the modern solar panel.

Solar panels use photovoltaic cells, or PV cells, to absorb light (in the form of photons) from the sun. When sunlight hits the panels, they generate a direct current, or DC, electricity. However, homes require alternating current, or AC, electricity.

A device called a solar inverter is a key part of the solar energy system, converting the electric current from DC to AC. The AC power then circulates through your household electrical panel and is distributed as needed to your different systems, appliances and outlets.

Before we dive into the science of solar panels on a molecular level, here’s a broad summary of how solar panels work:

  1. Photovoltaic cells absorb sunlight, then turn it into DC energy.
  2. An inverter turns the DC energy into AC energy, which is what your household electrical system requires.
  3. Electricity is distributed throughout your home, powering outlets and appliances.
  4. Any excess or leftover electricity that is produced is fed into a battery bank or back to your local power grid.

If your home is connected to the electrical grid (and most homes are), then it comes with a utility meter. This meter is what allows your utility company to measure how much energy you are consuming. During your solar panel installation, your solar system will typically be connected to the utility meter, so that you can measure the amount of electricity you produce versus the amount you consume. This ensures that you’re only paying for the electricity you pull from the grid and not the solar electricity you’re using.

The Science of Solar Panels

While there are varying types of solar panels to choose from, most residential and commercial solar systems work in roughly the same way. A metal frame and glass casing surrounds a thin layer of silicon cells. Wires throughout the panel allow for the free flow of electricity.

You may (or may not) remember from your high school science classes that silicon is a non-metal with conductive properties. In other words, silicon can absorb light and turn it into electricity. There are plenty of other semiconductors with the same properties, but scientists chose silicon for solar panels because of its relative abundance and affordability on a large scale.

How it works is simple: when light hits the silicon cells, electrons are set into motion, producing an electrical current. This flow of electricity was the process observed by Edmond Becquerel back in 1839 and has since been coined the photovoltaic effect, one of the core principles of solar technology.

More About the Photovoltaic Effect

Let’s dig into the photovoltaic effect a little deeper. The photovoltaic effect simply describes the property by which these materials can generate electricity any time they are exposed to sunlight.

Here’s a step-by-step summary of how solar panels work via the photovoltaic effect:

  1. Sunlight hits the solar panel, which has two layers of silicon: an N-type layer that sits on top of a P-type layer.
  2. The sun’s energy knocks an electron from its bond in the upper N-type layer, creating both a freely roaming electron and a positively charged “hole” where the electron was previously bonded.
  3. The hole travels down to the P-type layer, and the free electron is channeled through conductive wires to an inverter.
  4. The inverter transforms the solar electricity from DC to AC so that it can be used in your home.
  5. The electricity flows throughout your home to power systems, appliances and outlets.

How Solar Panels Work With Your Power Grid or Battery Bank

Many solar homes produce more energy than they need. We mentioned earlier that this excess electricity can either be fed back into the central power grid or stored in a solar battery. So, how do solar panels work with each component?

  • Power gridWhen you feed energy back into your power grid, if you have a local net metering program, you can receive credits from your utility company to save even more money on your monthly bills and help offset the cost of solar panels.
  • Battery: The best solar batteries have a high capacity so that you can store enough excess energy to power your home during power outages and on especially cloudy days. Batteries also provide backup power for outages during extreme weather events.

Additional Factors to Understand

Of course, any science as complex as solar science will have variations in design and development. As such, it’s important to consider the factors that might differentiate quality or intended use.

To begin, you might notice most solar panels are either monocrystalline or polycrystalline. Monocrystalline panels are made using a single silicon crystal. They tend to be the most efficient solar panels, though they can also be the most expensive. Polycrystalline solar panels are made up of multiple crystal fragments and usually cost less. Solar projects with limited space might opt for monocrystalline, while projects with lower power needs or ample space might prefer the affordability of polycrystalline.

We mentioned above that most solar panels come with a glass casing. This helps protect the silicon solar cells and ensures the longevity and durability of your home solar system. Beneath that glass case, there may also be some insulating materials, which protect your equipment from humidity as well as from heat dissipation. The casing and insulation are crucial to the overall efficiency and durability of a solar panel.

This might sound simple, but think about how you would safely encase a solar panel without reflecting any of the sunlight intended for absorption. Scientific challenges like this are what keep the industry moving forward.

Getting Started With Solar Energy

Now that you know how solar panels work, you may feel ready to get going with your own solar energy system. The first step is identifying the best solar installers in your area and calling an installer to find out if solar panels are worth it for your home. Your installer will conduct an assessment based on the size of your home, the surface area of your roof, the amount of sunlight you get and more. It will furnish some guidance as to how many solar panels you need and which type of panel is right for your installation.

Getting a home solar system can be a great way to save money on your monthly utility costs while demonstrating a real commitment to environmental stewardship. To start getting free quotes from solar installers in your area, you can use this tool or fill out the form below.

FAQ: How Solar Panels Work

Step by step, how do solar panels work?

Solar panels work by absorbing solar energy and converting it into usable AC electricity through this process:

  1. Photovoltaic cells absorb sunlight, then turn it into DC energy.
  2. An inverter turns the DC energy into AC energy, which is what your household electrical system requires.
  3. Electricity is distributed throughout your home, powering outlets and appliances.
  4. Any excess or leftover electricity that is produced is fed into a battery bank or back to your local power grid.

What are the two main disadvantages of solar panels?

The two main disadvantages of solar panels are that they only generate electricity when the sun is out, and they’re only effective on roofs with proper space and exposure to sunlight. To combat these disadvantages, manufacturers are developing solar batteries that store excess energy generated in daylight hours for use when the sun is down. You might also be surprised by how effective solar panels are on cloudy days.

Further, utility companies are investing in solar farms and community solar to share the benefits of solar with homes unfit for solar panels themselves.

Do solar panels work when there is no sun?

Solar panels do not generate electricity when the sun isn’t shining. However, most solar arrays generate more electricity during peak daylight hours than can be used in a day. Solar batteries are used to store this excess energy for use when the sun isn’t up.

Karsten Neumeister is a writer and renewable energy specialist with a background in writing and the humanities. Before joining EcoWatch, Karsten worked in the energy sector of New Orleans, focusing on renewable energy policy and technology. A lover of music and the outdoors, Karsten might be found rock climbing, canoeing or writing songs when away from the workplace.

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