Table of Contents:
Key takeaways
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Photovoltaic cells are the key component in solar panels that convert sunlight into usable energy.
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Manufacturers can make photovoltaic cells in several different ways.
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Photovoltaic cells come in different types, and the best option depends on your needs.
There are lots of parts to a solar panel, but only one of them actually does the job of creating energy you can use in your home—the photovoltaic cells. These cells are the essential components in a solar energy system, meaning it’s beneficial to understand what they are, how they work, and the features and applications of different types.
This guide provides all of that information to help you make the best decision on your solar technology investment. You’ll also learn the benefits and limitations of current photovoltaic cell development.
What are photovoltaic cells?
Photovoltaic cells are the “active ingredient” in solar panels. They are what capture sunlight and convert it to electricity through the photovoltaic effect. This effect occurs when sunlight is absorbed by the PV cells, which causes electrons to become excited. As these electrons move, they create an electrical charge.
What are solar cells made of?
While there are several materials that are used or being researched to use in solar cells, most PV cells fall into two categories. Each type of solar cell material has distinct properties that make them better for certain applications or purposes than others.
Here’s a closer look at the components of a PV cell:
| Component | Definition | Key Contexts |
|---|---|---|
| Silicon wafer | Thin layer of silicon that forms the base of the PV cell | Crystalline or amorphous; absorbs photons; supports current generation |
| Anti-reflective coating | Coating applied to surface to reduce light reflection | Maximizes light absorption; typically made of silicon nitride or titanium dioxide |
| Glass cover | Protective outer layer of the PV cell | Transparent; shields against weather and physical damage |
| Encapsulant | Material surrounding PV cell layers for insulation and durability | Usually EVA (ethylene-vinyl acetate); ensures longevity and protection from moisture |
| Front contact | Thin metallic lines on the top of the cell | Collects electrons; typically made from silver or other conductive materials |
| Rear contact | Conductive layer at the back of the cell | Completes the electrical circuit; usually aluminum |
| P-type layer | Silicon doped with boron to create positive charge carriers | Forms part of the PN junction; facilitates current flow |
| N-type layer | Silicon doped with phosphorus to create negative charge carriers | Creates the other side of the PN junction; enables electron movement |
| PN junction | Interface between p-type and n-type silicon | Generates electric field; essential for separating charge carriers |
| Busbars | Wider metal strips connecting multiple front contacts | Conduct electricity out of the cell; minimize resistance and energy loss |
Crystalline Silicon (c-Si)
By far, the most common material used for photovoltaic cells is crystalline silicon (c-Si). Silicon is not especially efficient as a semiconductor on its own. However, after being infused with boron on one side of the cell and phosphorus on the other, the end product, silicon crystals, are excellent solar energy semiconductors.
The two types of c-Si solar cells are:
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Monocrystalline solar cells: Cut from a single piece of silicon crystal, monocrystalline panels are the more efficient of the two types.
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Polycrystalline solar cells: These cells are made by fusing several smaller pieces of silicon together to form a single sheet. While they are less efficient than monocrystalline cells, polycrystalline panels are also less expensive.
Thin-Film Materials
The other main category of materials used to make photovoltaic cells is thin-film materials. Compared to silicon crystal cells, PV cells in thin-film solar panels are cheaper, lighter, and more flexible. This makes them a popular choice for large-scale applications where space efficiency isn’t a concern and in portable applications.
The three main materials used to make thin-film PV cells are:
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Cadmium telluride (CdTe): Thin-film solar cells made from cadmium telluride are efficient and relatively inexpensive. However, cadmium is considered toxic, raising concerns about its use.
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Copper indium gallium selenide (CIGS): CIGS-based PV cells have strong low-light performance compared to other types. However, they are complex to manufacture, making them difficult to produce at scale for consumer products.
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Amorphous silicon (a-Si): Solar cells made from amorphous silicon are inexpensive and less resource-intensive to manufacture. Their low solar efficiency compared to other thin-film materials is a significant drawback.
How panels convert sunlight using the photovoltaic effect
Solar energy production is made possible by the photovoltaic effect. Here’s a simplified step-by-step process of how solar panels convert sunlight into energy:
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The PV solar cell absorbs sunlight.
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The sunlight excites the electrons within the cell.
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The energized electrons move across the cell, creating an electrical charge.
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This movement generates direct current (DC) energy.
However, home fixtures and appliances use alternating current (AC) energy. That means that the energy created by the photovoltaic cells must first go to a solar inverter, where it is transformed into AC electricity. Once transformed, the electricity can be used exactly as power from the energy grid is, with energy flow managed by the solar charge controller.
How the photovoltaic cell structure shapes electrical output
In addition to the materials used in solar cells, how those cells are constructed is an important factor in their ability to generate energy. The photovoltaic cells in panels use a layered construction to optimize their energy efficiency and longevity.
Photovoltaic cells are constructed with the following layers:
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Top anti-reflective layer: The top layer of a photovoltaic cell is designed to minimize reflection of light, ensuring the maximum amount of available sunlight passes through to the reactive layers.
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Glass or plastic cover: Transparent glass or plastic sits on top of the photovoltaic layers to protect it from the weather and other environmental hazards.
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Front contact layer: The first contact layer in the assembly conducts electrons from the PV layers to external circuits.
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Semiconductor layers: The two semiconductor layers are responsible for energy creation. One layer is doped with boron, which carries a positive charge (p-type), while the other is doped with phosphorus, which carries a negative charge (n-type). The contrasting charges of these materials cause the electrons to move, generating an electrical current.
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Back contact layer: The bottom layer of a photovoltaic cell is what closes the electrical circuit.
Types of photovoltaic panels for different applications
Solar engineers have developed several types of photovoltaic panel structures that are optimized for different purposes. These include:
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Conventional flat-plate modules: These PV panels are the most common type of consumer panels. They’re used on the roofs of buildings in both grid-connected and off-grid solar setups, in hybrid solar systems, in fields on solar farms, and even on satellites.
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Building-integrated photovoltaics (BIPV): Some manufacturers produce photovoltaic cells that serve as actual building materials, allowing them to become part of the architecture. For residential applications, one popular example is solar shingles.
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Concentrated photovoltaics (CPV): These photovoltaic panels employ specialized lenses or mirrors to intensify sunlight and improve solar efficiency. Their high relative cost compared to other types of panels has limited their market penetration up to this point.
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Floating solar: Some photovoltaic panels are constructed to sit on top of bodies of water. This application helps keep solar panels cool, maximizing efficiency, and reduces the use of land for solar energy generation.
Factors that affect photovoltaic cell efficiency
The solar efficiency of photovoltaic cells varies based on a few main factors. These include:
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Photovoltaic cell material: As illustrated earlier, different materials used to make PV cells have different levels of efficiency.
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Construction: The way PV cell panels are constructed and the other materials used in the assembly can also limit or improve solar efficiency. Some panels have tracking systems that can rotate them to follow the sunlight.
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Location: The efficiency of photovoltaic cells is determined by the amount of light that can reach the cells. Solar panels located in heavily shaded areas or in places that get lots of cloud cover regularly simply won’t be able to generate energy as efficiently.
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Installation: How photovoltaic cells are actually installed on a property is a factor as well. For every installation, there is an ideal angle for maximizing the sunlight captured in the PV cells.
Benefits and limitations of photovoltaic cell technology
The obvious benefit of photovoltaic cell technology and the one that is a deciding factor for many people is cost. While solar energy systems that use PV cells are a major purchase at an average cost of $17,823, they often pay for themselves within a decade and continue to provide “free” energy for a decade or more after.
However, there are other benefits to photovoltaic cells beyond saving you money. Advances in PV cell technology have made it more feasible than ever for people to switch to renewable energy for powering their homes and their lives.
There are still some limitations to photovoltaic cell technology at this time, though. Despite increases in efficiency, energy production is limited by how much light is available. That means that even high-efficiency PV cells may not be able to generate enough power to meet homeowners’ needs in certain parts of the country.
Plus, there are sustainability concerns with harvesting the materials used to make photovoltaic cells and in the processes used to manufacture them. This is an especially important limitation to address as global demand for photovoltaic cell solar panels continues to grow.
Bottom line: understanding photovoltaic cells
Photovoltaic cells are the part of solar panels that allow them to generate clean, renewable energy for our homes and businesses. Recent advances in PV cell technology have made them more efficient, more affordable, and more diverse in construction and application.
Understanding how photovoltaic cells work, how they are made, and the differences between them can help you make the right decision about which type of cells you buy for your solar energy system. At the end of the day, solar panels are great for some homeowners but not the best for others.
FAQ about photovoltaic cells
Below are a few frequently asked questions about photovoltaic cells:
What is a photovoltaic cell, and how does it work?
A photovoltaic cell is the part of a solar panel that absorbs sunlight and converts it to electricity. It works through the photovoltaic effect, where sunlight stimulates electron activity, which creates an electrical charge.
What is the difference between solar panels and photovoltaic cells?
Photovoltaic cells are a component of solar panels. They are the part of the solar panels where sunlight is converted to energy. The term solar panel refers to the entire assembly.
What are the three drawbacks of photovoltaic cells?
Three of the most notable drawbacks of photovoltaic cells are sustainability concerns about harvesting the materials used to make them, their dependency on sunlight availability, and their limited affordability.
What is CPV solar?
Concentrated photovoltaic solar, or CPV solar, is a design for solar panels that uses mirrors and/or lenses to intensify light and improve solar efficiency. While not yet in widespread use compared to other types of solar technology, CPV solar shows significant promise for potential future adoption.
What are n-type photovoltaic cells?
N-type solar panels use negatively-charged, or n-type, silicon to encourage electron activity. They are generally more efficient than solar panels with p-type solar modules.