How do solar panels work? Solar power explained

You probably already know that solar panels capture energy from sunlight and turn it into clean, usable electricity. But have you ever wondered what actually happens inside a solar panel to make that possible?

At a basic level, solar panels are built from solar cells that absorb sunlight. These cells use the incoming sunlight to produce direct current (DC) electricity through a process known as the photovoltaic effect. Since most household appliances operate on alternating current (AC), special devices called inverters change the DC electricity into AC electricity that your home can use. This usable electricity can ultimately help reduce your electricity bills.

You don't need to understand every technical detail to get the basic idea. However, if you're curious about how solar panels produce electricity, there are a few important concepts worth knowing.

What exactly is solar energy?

Solar energy refers to the light and heat produced by the sun. To understand where this energy comes from, it helps to begin with one of its smallest components: the photon.

Photons have properties of both waves and particles and are produced deep within the sun's core, where nuclear fusion takes place. The temperature at the sun's core reaches an extraordinary 27 million degrees Fahrenheit. Under such extreme heat and pressure, hydrogen atoms collide and combine to form helium. This fusion reaction releases enormous quantities of energy in the form of photons.

Nuclear fusion inside the sun happens continuously. More than 500 million tons of hydrogen are transformed into helium every second, producing the photons that carry solar energy from the sun toward Earth.

How solar panels work through the photovoltaic effect

In simple terms, a solar panel makes electricity when photons from sunlight strike its solar cells. This process is called the photovoltaic effect.

Edmond Becquerel first identified the photovoltaic effect in 1839. It is a characteristic of certain materials, called semiconductors, that allows them to produce an electric current when exposed to light.

Around 95% of solar cells are manufactured using silicon. Silicon is a nonmetal semiconductor that is capable of absorbing sunlight and converting its energy into electricity. The basic process works as follows.

Solar cells contain two layers of silicon. Each layer is specially treated, or doped, with different materials. Phosphorus is used to create one side with a negative charge, while boron creates the positively charged side. When sunlight reaches the cell, it produces an electric field where the two layers meet.

The electric field causes electrons to break free from their atoms within the solar cell and begin moving.

These freed electrons travel through the solar cell and move away from the junction, creating an electrical current.

Metal contacts positioned on the sides of the solar cells collect this current and direct it into connecting wires.

The electricity then travels through those wires to one or more solar inverters. The inverter changes the electricity into a form that can be used by appliances and other electrical devices in your home.

Alternatives to silicon solar cells

Thin-film technology is another approach to producing solar cells. Instead of relying on the traditional silicon cell structure, thin-film solar cells use very thin layers of photovoltaic material to capture sunlight and produce electricity.

What are solar panels made of?

A standard solar module contains several important components that work together to capture sunlight and produce electricity.

Solar cells are the main working components of a panel. They absorb sunlight and convert it into electrical energy. Most silicon solar cells fall into two main categories: monocrystalline and polycrystalline. Monocrystalline cells are produced from a single silicon crystal, while polycrystalline cells are formed from multiple silicon fragments.

A glass covering sits over the solar cells and provides protection against weather and other environmental conditions while also helping keep the cells durable.

An insulation layer and back sheet are located beneath the glass surface. These materials help protect the panel from excessive heat and moisture, both of which can negatively affect the panel's performance.

An anti-reflective coating helps more sunlight enter the solar cells instead of being reflected away from their surface.

A 12V wire helps regulate the amount of electricity sent toward the inverter.

Bus wires connect the individual silicon cells and allow electrical current to move between them.

How do solar panels generate electricity for your home?

Producing an electrical current is only the beginning of the process. A complete solar power system must take that electricity and transform it into a usable form for your household.

Once the solar cells generate DC electricity, the current travels through the panel wiring toward the inverter. The inverter converts the DC power into AC electricity, which is the type of electricity normally used by household appliances and electrical systems.

From there, the electricity can be supplied to the home's electrical system and used to power everyday devices. In this way, sunlight captured by the solar panels becomes usable electrical energy for the home.

What types of solar technology exist?

Most of the discussion around solar power focuses on photovoltaic, or PV, technology because it is the form of solar energy most commonly used by homes and businesses to generate electricity. However, solar technology also includes other methods that use sunlight in different ways.

Solar hot water heater

Solar hot water systems collect thermal energy from the sun and use that heat to warm water for a home. Unlike photovoltaic panels, these systems do not need to produce electricity.

A typical solar hot water setup contains collectors, a storage tank, a heat exchanger, a control system, and a backup heater.

Instead of moving electrons and generating electrical current, the collectors convert sunlight directly into heat. Sunlight travels through a transparent glass covering and reaches an absorber plate beneath it. The plate captures the solar energy and turns it into heat.

That heat is then transferred to a fluid, which may be water or antifreeze, flowing through small pipes within the absorber plate. The heated fluid eventually transfers its heat to the water stored in the household tank.

Concentrated solar power

Concentrated solar power, or CSP, also begins by transforming sunlight into heat, but it uses that heat in a different way. CSP systems employ mirrors to concentrate sunlight onto a specific point, producing extremely high temperatures.

The intense heat is then used to generate steam, which drives a turbine and produces electricity.

CSP is mainly used for large, utility-scale power facilities rather than typical residential systems. These plants send electricity to the power grid and provide a renewable alternative to conventional fossil-fuel power stations.

One advantage of concentrated solar power is that it can be combined with thermal energy storage. This makes it possible for some CSP facilities to continue producing electricity even after direct sunlight is no longer available.