Are Solar Cells And Photovoltaic Cells The Same Thing?

Solar cells and photovoltaic cells are often used interchangeably to refer to the same technology that converts sunlight into electricity. In short, yes, solar cells and photovoltaic cells are the same thing. They both refer to devices that convert light energy from the sun directly into electrical energy through the photovoltaic effect.

The terms “solar cell” and “photovoltaic cell” are synonymous and describe the fundamental power conversion unit used in photovoltaic solar panels. While the terms are used interchangeably, “photovoltaic cell” emphasizes the operating principle of converting photons from sunlight into electricity, while “solar cell” focuses more simply on the sun as the light source. But both refer to the same underlying technology and phenomenon.

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History

The history of solar cell technology dates back to the 19th century when the photovoltaic effect was first observed. In 1839, French physicist Edmond Becquerel discovered that certain materials would produce small amounts of electric current when exposed to light. It took several decades before the first solid state photovoltaic device was created. In 1883, American inventor Charles Fritts constructed the first solar cells using selenium wafers. These early solar cells were only about 1% efficient in converting sunlight to electricity.

In the early 20th century, Albert Einstein went on to describe the nature of light and the photoelectric effect, for which he later won the Nobel Prize in Physics in 1921. His work formed the scientific basis for photovoltaic technology. In 1954, researchers at Bell Laboratories in the United States produced the first modern silicon solar cell with a sunlight to electricity conversion efficiency of about 6%.

Through the 1950s and 1960s, photovoltaic technology was primarily used to provide power aboard spacecraft. It was very expensive to produce solar cells at the time. In the 1970s, Exxon and other oil companies began developing more cost-effective ways to manufacture solar cells, making them a more viable energy source on Earth. Since then, solar cell technology has continuously improved while costs have declined dramatically. Today, solar energy is one of the fastest growing renewable energy sources worldwide.

How They Work

Solar cells, also known as photovoltaic cells, convert sunlight directly into electricity using the photovoltaic effect. This process relies on materials called semiconductors, such as silicon, which have distinct electrical properties. When sunlight hits the solar cell, the energy from the photons of light excites the electrons in the semiconductor material, causing them to break free from their atoms. This generates electron-hole pairs, which produce an electric current as the electrons move to one side of the cell and the holes move to the other side. The electrons then flow through an external circuit and eventually reunite with the holes at the other end. This flow of electrons produces the electric current and voltage needed to power devices and appliances.

The unique atomic structure of semiconductor materials makes the photovoltaic effect possible. Semiconductors have a distinct energy band gap between the valence band and conduction band that allows electrons to easily jump when exposed to sunlight. The most common material for solar cells is crystalline silicon, which is doped with other elements to enhance its conductive properties. When sunlight enters the cell, it excites the electrons enough to jump across the energy band gap into the conduction band, producing electricity.

Types

There are a few main types of solar cells and photovoltaic cells:

Monocrystalline solar cells are made from a single silicon crystal. They have a uniform appearance and color, and are the most efficient type of solar cell, with typical efficiencies of 15-20%. However, they are more expensive to manufacture than other types.

Polycrystalline solar cells are made from multiple silicon crystal fragments melted together. They have a speckled blue color and are less efficient than monocrystalline cells, with typical efficiencies of 13-16%. However, they are easier and cheaper to produce.

Thin-film solar cells use very thin layers of photosensitive materials deposited on glass, plastic or metal substrates. Types of thin-film cells include cadmium telluride (CdTe), copper indium gallium selenide (CIGS), and amorphous silicon (a-Si). Thin-film cells are less efficient than crystalline silicon cells, with typical efficiencies of 7-13%, but can be flexible and have other advantages.

There are also multi-junction or tandem solar cells that combine multiple semiconductor materials to improve efficiency. Concentrator photovoltaics focus sunlight on small high-efficiency solar cells. Emerging types like perovskites and organic photovoltaics are still in research and development stages.

Efficiency

The efficiency of a solar cell refers to what percentage of the sunlight striking the cell gets converted into electricity. The more efficient a cell is, the more electricity it can produce from the same amount of sunlight. Most mass-market solar panels today have efficiencies in the range of 15-22%.

There are several factors that play into a solar cell’s efficiency:

The materials used – Some semiconductor materials like monocrystalline silicon are more efficient at converting sunlight into electricity than amorphous silicon.

Manufacturing quality – Defects introduced during manufacturing can reduce efficiency. Premium solar panels tend to have higher quality standards and efficiencies.
Temperature – Solar cell efficiency decreases as temperature increases. Keeping panels cool, such as with integrated microinverters, can maintain higher efficiencies.
Angle to the sun – Efficiency is maximized when sunlight hits the solar panel perpendicularly. Tilting panels to track the angle of the sun can improve efficiency.

Shading – Even small amounts of shading on a solar panel can drastically impact efficiency. Keeping panels free from obstructions is key.

Researchers continue to work on developing new materials and production methods to increase solar cell efficiency. The world record for a production solar cell is currently around 27% efficiency. Some experimental solar cells in laboratories have exceeded 45% efficiency.

Cost

The cost of solar cells and photovoltaic panels has declined significantly over the past few decades as production has scaled up massively. In 1977, the cost per watt of solar panels was around $77. Today, the average cost is around $0.30 per watt. This represents a massive 99% drop in costs. Several factors have driven down costs:

Economies of scale – As more solar panels are manufactured, costs are spread across higher production volumes resulting in lower per unit costs.
Technology improvements – Advances in solar cell technology and manufacturing processes have improved efficiency and yields while reducing material and energy inputs.
Supply chain development – Mature supply chains for materials and components like silicon wafers and aluminum frames have reduced costs.

Competition – Many companies now manufacture solar panels leading to competitive pressures and the need for lower costs.

With solar already at cost parity with fossil fuels in many regions and costs projected to fall further, solar power is becoming an increasingly economically compelling renewable energy source.

Applications

Solar cells and photovoltaic (PV) panels have a wide range of applications, from small consumer electronics to large utility-scale power plants. Some of the most common applications include:

– Calculators and watches – Tiny solar cells have powered calculators, watches, and other small devices for decades.

– Off-grid lighting and electronics – Solar panels provide electricity for lighting, appliances, phone charging, and more in rural or remote areas without access to an electricity grid.

– Home rooftop systems – Homeowners are installing rooftop solar PV systems to reduce their electricity bills and offset grid power with renewable energy.

– Commercial/government buildings – Businesses, schools, government facilities and more are adding solar PV systems to rooftops or ground-mounts to save money and meet sustainability goals.

– Solar farms – Large ground-mounted PV systems generate renewable electricity to feed into the grid; utility companies are increasingly investing in these to meet renewable portfolio standards.

– Spacecraft and satellites – Solar provides reliable power for satellites, space stations, Mars rovers and other spacecraft.

– Electric vehicles – Solar EVs like the Lightyear One use solar panels integrated into the roof and hood to charge the battery and increase driving range.

– Solar roadways and infrastructure – While still in R&D stages, integration of PV cells into roads, sidewalks, sound barriers and other infrastructure may emerge in the future.

From powering simple devices to megawatt utility projects, solar PV offers versatility across many applications and scales.

Future Outlook

The future looks bright for solar cells and photovoltaic technology. As research and development continues, we can expect to see improvements in both efficiency and costs.

Solar cell efficiency records are consistently being broken. In the lab, scientists have achieved efficiencies over 40% for certain multi-junction solar cells. Commercial modules typically have 15-20% efficiency today, but improvements in materials and manufacturing methods will enable higher efficiency modules to become mainstream in the coming years.

Prices for solar panels have dropped dramatically in the past decade, making solar power cost competitive with fossil fuels in many parts of the world. Experts predict PV system prices will continue to fall, as economies of scale further reduce manufacturing and soft costs. The U.S. Department of Energy has set cost targets to make unsubsidized solar energy widely affordable within the next decade.

With these improvements, solar is expected to continue its rapid growth worldwide. Total global solar PV capacity is forecast to expand greatly in the coming decades. Solar energy has huge potential to displace fossil fuel electricity generation and help mitigate climate change.

Environmental Impact

The use of solar energy has significant positive impacts on the environment compared to fossil fuels like coal, oil, and natural gas. Some key benefits include:

Reducing greenhouse gas emissions – Solar panels produce electricity without releasing any carbon dioxide, methane, or other polluting gases that contribute to climate change.

Improving air quality – Less reliance on fossil fuel plants means lower emissions of sulfur dioxide, nitrogen oxides, particulates, mercury, and other hazardous air pollutants.
Conserving water – Solar photovoltaics use far less water than coal, natural gas, or nuclear power plants that rely on water for cooling and steam generation.
Preventing habitat destruction – Solar arrays can be built on land like old industrial sites, limiting the need to disrupt natural habitats to access fossil fuel reserves.

Lower toxic waste – The manufacturing of solar cells produces negligible toxic waste compared to the ash, sludge, or contaminated water from fossil fuel power.
Quieter operations – Solar panels have no moving parts and are silent during operation, reducing noise pollution.

With benefits like these, solar energy can help address many pressing environmental problems while still meeting the world’s energy needs in a renewable and sustainable way.

Conclusion

In summary, solar cells and photovoltaic (PV) cells refer to the same technology that converts sunlight into electricity. While the terms are sometimes used interchangeably, “photovoltaic cell” is considered more technically accurate. PV cells use the photovoltaic effect to absorb photons from sunlight and generate an electric current. The word “photovoltaic” specifically refers to this light-to-electricity conversion process. Meanwhile, “solar cell” is a more general and informal term for the same device. Both terms describe the key component used in solar panels to produce renewable solar energy. So in conclusion, PV cells and solar cells are simply two names for the same fundamental technology that harnesses solar energy.