What are solar panels?

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large solar panel array
Solar panels convert sunlight into usable electricity. Image source: Scientific American

Solar panels, or photovoltaic (PV) panels, convert solar energy from the sun into usable electricity. The photovoltaic effect, or the ability to generate electricity from sunlight through electrons, was first observed in the late 1800’s, which then led to the invention of the first solar cell by Charles Fritts. 

However, it was not until 1954 that solar cells were developed, which led to the creation of solar panels built from multiple solar cells. 

Solar panels were not commercially viable or truly efficient at absorbing and generating a usable amount of electricity until after the invention of high-silicon PV panels in 1954 at Bell Labs. Since then, solar has evolved to become one of the cheapest forms of clean energy available and continues to increase in popularity.

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    How do solar cells and solar panels work?

    The most important component of a solar panel is the photovoltaic cell. Solar cells convert sunlight into electricity through the photovoltaic effect, hence the name ‘PV panels’. 

    Solar cells are made up of the semiconductor crystalline, silicon. Silicon is photovoltaic, which means that it is a substance that reacts when exposed to light, and in this case, the reaction generates electricity.  

    In addition to solar cells, solar panels are composed of an aluminum frame, tempered glass, encapsulate EVA to protect the cells, a backsheet, and a junction box to attach wiring from the solar panels.

    Within each PV cell, there is a negative layer and a positive layer. The negative layer has extra electrons and the positive layer has extra space for those electrons to move to when the sun hits the panel. Photons, or the sun's rays, are the energy that forces the electrons to move from the negative to the positive layer to produce electricity. 

    When exposed to sunlight, solar cells generate an electric current - direct current, also referred to as DC electricity - which is then converted to usable alternating current (AC) electricity through an inverter. This AC electricity is what powers your home, and is stored in your solar battery for future use or is sent back to the power grid.

    The most common types of solar PV panels are monocrystalline and polycrystalline. The main difference between monocrystalline and polycrystalline panels is that the more-efficient monocrystalline is made from a single crystal silicon solar cell, while polycrystalline is made from melting several silicon crystals together. 

    Many silicon crystals are then assembled along with solar cells to form one panel.

    Learn more: Monocrystalline vs. polycrystalline solar panels

    What do solar arrays consist of?

    components of a solar array

    Aside from the solar panel itself, the key components of a solar energy system are the racking system and the inverter. 

    Racking 

    Racking systems can either be ground-mounted, as pictured above, or mounted on your roof as is typical on home installations. 

    Solar racking and mounting systems are what holds the solar panels in place, either on a rooftop or on the ground. There are even options that can track the sun to absorb as much sunlight as possible, although these cost substantially more. 

    For more detail about racking systems, review our guide to solar panel mounts

    The inverter 

    Inverters create usable electricity from each solar panel. In other words, it is what converts the DC energy generated by the solar panel into usable AC electricity for your home. 

    An inverter has three main roles:

    • To convert DC energy into AC electricity
    • To communicate with the grid
    • Act as a way to shut down your solar panels if there are any issues with wiring or other hazards 

    The inverter is the key part of your solar PV system, your home would not be able to use the power produced by solar panels without it. Learn more about inverters, as well as the key differences between microinverters and string inverters, here

    Working with a local solar installer can help you determine which racking and inverter types make the most sense for your solar system.

    What types of solar systems can work on your home?

    There are three main types of solar systems that make sense for residential homes: grid-tied, hybrid, and off-grid. 

    Grid-tied solar systems 

    The most common type of solar system is a grid-tied system. With grid-tied systems, your solar panels are connected to the grid, meaning you can still pull energy from the utility when your solar resources are low. 

    This is generally the best option because you can rely on the grid as backup power for nighttime use or on rainy days when your panels are not producing electricity. In most states, you can also benefit from net metering by selling your energy back to the grid.

    Hybrid solar systems 

    Hybrid systems are similar but they also include a solar battery, meaning your solar panels charge the battery for backup use during power outages or for nighttime use. 

    Hybrid solar systems are still connected to the grid so both the grid and the battery can act as a power resource. Batteries are a great investment for energy resilience but are definitely a large financial add on to a solar system. 

    Off-grid solar systems 

    An off-grid system is the least practical because you will need a lot of solar panels and backup batteries to make sure you can make it through the cloudiest of weeks. 

    Off-grid does make sense for remote homes that are not connected to a local power line. But for most residential homes, a hybrid or a grid-tied system is the easiest and best way to power your home with solar. 

    Calculate your solar panel payback period

    Solar panels are a key part of the future of energy

    Solar panels are a popular option for homeowners who are interested in energy resilience. If you install a solar system and a storage battery, your home can act like its own power grid during outages. 

    Solar panel systems can also help reduce your monthly electricity bill, especially if you live in a location with net metering benefits. 

    Solar power is projected to be a key part of the renewable energy mix for the United States as solar technologies are becoming more advanced each year and will help reduce emissions from fossil fuel plants by diversifying energy production.

    Key takeaways

    • The photovoltaic effect was discovered in the late 1800’s and led to a gradual increase in the use of solar panels. Today, solar is a major global electricity provider.
    • Using silicon solar cells, solar panels produce direct current (DC) electricity via a solar inverter, which converts it into alternating current (AC) electricity to power homes and businesses.
    • A solar system’s main components are the solar panels, solar racking, and most importantly, the solar inverter.
    • The three main types of solar systems are grid-tied, hybrid, and off-grid. Grid-tied and hybrid solar systems are the most practical for residential homes.
     - Author of Solar Reviews

    Ana Almerini

    Web Content Specialist

    Ana is a web content specialist at SolarReviews. She has 5 years of marketing experience blended with 2 years of experience in climate communications and holds a master of arts degree in climate and society from Columbia University. Ana frequently volunteers for environmental causes ranging from oyster reef restoration in NJ to expanding bike sharing in Naples, Italy.

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