How Do Solar Panels Generate Electricity?

Tori Barrington

Key Points (TL;DR)
  • PV cells are made from semiconductor materials, like silicon.
  • Solar panel cells generate electricity through the photovoltaic effect.
  • PV cells have a negatively charged layer and a positively charged layer, which creates an electric field to conduct the flow of electrons.
  • Solar panels create direct current (DC) electricity, which passes through an inverter and is converted into alternating current (AC) electricity.
  • A backup battery can store excess electricity for use during storms or power outages.
  • A utility meter tracks the flow of excess electricity from your home to the grid.
  • Q&A
    How do solar panels power a house? Solar panels are composed of PV cells, which use the photovoltaic effect to convert sunlight in direct current (DC) electricity.

    Houses are powered by alternating current (AC) electricity, so the DC current generated by the solar panels passes through an inverter and is converted into AC electricity, which can then power the home.

    Do solar panels work at night? Solar panels need sunlight to create electricity, so they do not function during the night. If you have a backup battery, the solar energy stored inside can be used during the night.

    Otherwise your home will need to pull electricity from the utility grid at night.

    What is a photovoltaic cell? A solar panel is made up of many photovoltaic cells, or PV cells. These cells are made from semiconductor materials, like silicon, which allows them to create electrical currents and convert sunlight into electricity.
    How long do solar panels last? Solar panels are usually built to last between 25 and 30 years.

    Before discussing how solar panels work, it is important to understand what they are made of.

    What are solar panels made of?

    Each individual square on a solar panel is called a photovoltaic cell (PV cell), meaning it can convert sunlight into electricity through the photovoltaic effect. In order for this specific effect to take place, the solar cells must be made from specific materials.

    The majority of PV cells are made from silicon, because silicon is a semiconductor material. Thin film solar panels are made from other materials, including CdTe (cadmium telluride), gallium arsenide (GaAs) and Copper Indium Gallium Selenide (CIGS), which are also all types of semiconductors.

    PV cells must be made from semiconductor materials, because they have properties that allow them to conduct electricity.

    The solar cells are made up of two different layers.

    In the top layer, silicon is bonded to a material, like phosphorus, that has extra electrons. This makes the layer negatively charged. In the bottom layer, silicon is bonded to boron or gallium, which have less electrons. When the materials bond, this layer becomes positively charged.

    These two oppositely charged layers create an electric field, which allows for the flow of electrons.

    How does a solar panel system work?

    The material that solar panels are made of give them the ability to convert sunlight into electricity through the photovoltaic effect.

    Heat Map 2

    The Photovoltaic Effect

    The photovoltaic effect occurs when sunlight hits the PV cells of a solar panel.

    Photons are particles of light that contain energy. When sunlight strikes the semiconductor material of the cell, the energy from the photons knocks electrons loose. The oppositely charged layers of the cell generate an electric field, forcing the loose electrons to move in one direction.

    This movement of electrons is an energy current, which creates electricity. However, the electricity produced through this process is direct current (DC) electricity, and most homes and buildings use alternating current (AC) electricity.

    Generating Usable Electricity

    Because appliances are not powered by the type of electricity generated through the photovoltaic effect, a solar inverter is one of the most important parts of a solar panel system.

    The solar cell forces the energy current to move in one direction towards a wire, which then directs the electricity towards an inverter.

    An inverter very quickly switches the direction of the DC current back and forth until it has been converted into AC current electricity.

    Another wire transports the usable electricity to the breaker box where it is distributed to power appliances and lights throughout your home.

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    Excess Energy Storage

    If your solar panel system is generating more than enough electricity for your home, there are two options for where the excess energy can go.

    First, you can invest in a backup battery. Solar batteries can especially come in handy if you live somewhere with a high risk for power outages or severe weather, because they store electricity to be used at night or in emergency situations.

    Excess energy is stored in a backup battery in the form of DC current. When your home needs to use the backup power, the energy will pass through the inverter and be converted into AC current before it reaches the breaker box.

    If your system produces more solar energy than your home needs and you don’t have a backup battery, the excess energy will pass from the breaker box to the utility grid. A utility meter tracks the flow of electricity to and from your home, crediting you for the excess energy provided.

    There will most likely be times when your home will pull electricity from the grid, like during the night. The utility meter will track that too, but that cost can be offset by any excess energy your system generates for the grid.

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