How Do Solar Cells Work?

Solar cells are devices that help convert sunlight directly into electricity. In order to understand how solar cells work, one first needs to understand the process of manufacturing solar cells in detail. In the entire solar panel system, solar cells or photovoltaic (PV) cells are considered the fundamental components and are widely used in multiple applications.

As more and more people are getting inclined towards the usage of solar energy to reduce their electricity bills and help the environment, a thorough understanding of the working principle of solar cells helps the residents make a well-informed decision about adopting solar power.

If you are also aiming to opt for a sustainable solution that meets your off-grid requirement, or if you are focusing on reducing your monthly electricity bills, you can go ahead with Renogy.

What are solar cells?

Solar cells are semiconductor devices that convert sunlight into electrical energy. Solar cells or photovoltaic (PV) cells are made from silicon, which generates an electric current when exposed to light. Typically, each solar cell consists of multiple layers, each consisting of a positive and a negative layer that helps create an electric field.

When sunlight strikes the cells, it excites the electrons, which cause them to flow and generate electricity. According to EIA, individual PV cells come in different sizes, ranging from 0.5 inches to about 4.0 inches across. However, one PV cell is capable of powering only small devices like calculators or wristwatches.

How does a solar cell work?

The inner working mechanism of solar cells helps one understand how sunlight is transformed into AC electricity. This conversion process is commonly referred to as a photovoltaic effect and helps one analyze the process behind harnessing renewable energy.

Here's a step-by-step process depicting how does a solar cell work:

Absorption of sunlight

The photovoltaic effect begins when bright sunlight hits solar cells. As mentioned earlier, solar cells are typically made of semiconductor materials that can absorb photons from sunlight. These harnessed photons play a crucial role in generating electricity from this renewable energy source.

Generation of electron-hole pairs

Once the photons are absorbed by the silicon, their energy is transferred to electrons in the material. This added energy excites the already present electrons and further causes them to break free from their already existing atomic bonds.

This breaking of their atomic bonds creates electron-hole pairs, where these "holes" are the absence of an electron in the atomic structure.

Creation of an electric field

The photovoltaic (PV) cells are constructed with a built-in electric field that helps drive the movement of the electrons. This electric field is created by the junction of two different types of semiconductor material:

• N-type:N-type represents the excess of electrons
• P-type:P-type represents the excess of holes.

When both of these semiconductor materials are placed together, they form a p-n junction. The electric field present at this junction pushes the free electrons toward the n-type layer, and the holes are pushed toward the p-type layer.

Separation & direction of charge carriers

Due to the presence of the electric field, the free electrons are later driven towards the cell's surface. Metal contacts collect these free electrons on the surface area, which typically form a grid pattern.

Similarly to the electrons, the holes are also driven towards the opposite side of the cells. These holes are also collected by the metal contacts. When the cells are connected to an external circuit, this separation of the electrons and holes creates a flow of electric current.

Flow of electric current

The flow of electrons through the circuit is what we refer to as electricity. Once the electrons come in contact with the metal surface, they flow through an external circuit, which provides electric power to any connected load. After the electrons are passed through the external circuits, they are returned to the solar cells and recombined with the holes on the other side to restart the process.

In order to understand how solar cells work, let's take an example where a proper solar panel is installed on the rooftop. This solar panel is made up of multiple individual photovoltaic cells that are connected together. When the sunlight strikes these cells, the photons get excited, and the entire process of harnessing to conversion occurs simultaneously in each cell that generates DC electricity.

Once the solar panels create this DC electricity, it is then converted to alternating current by an inverter, like Renogy's 1000W 12V Pure Sine Wave Inverter, which makes it suitable for household and outdoor adventures.

How are solar cells made?

The manufacturing process of solar cells involves the transformation of raw silicon into energy-harvesting devices. Even though the process is highly meticulous, it highlights the complexity and innovation that goes behind the understanding of how does solar cell works for residential and commercial solar panels:

Purification of Silicon: The first and foremost step in creating solar cells is purifying them after they are extracted from sand or quartz. Once the solar cells are purified, they are melted and transformed into cylindrical ingots.

Cutting Silicon Wafers: Diamond wire saws slice these cylindrical ingots into thin wafers, which later form the base material for solar cells.

Doping Process: After getting the thin wafer sliced ingots, the manufacturers add phosphorus to the top layer, creating an n-type semiconductor. Simultaneously, boron is also added to the bottom layer to create a p-type semiconductor.

Anti-reflective & Metal Contacts: In order to reduce reflection and increase light absorption, an anti-reflective coating is then applied to the surface of the wafers. Once that is down, metal contacts are then printed on the front and back to allow the flow of the electric current.

Assembling Solar Panels: Once the metal printing is done, all the finished solar cells are connected together to form a grid pattern.

Application of Solar Cells

From residential power generation to commercial and industrial usage, solar cells provide sustainable and efficient solutions. Some of the most notable applications of solar cells are to power portable chargers and street lights, charge appliances in remote locations, and more. A few notable applications of solar cells are:

• Power Generation: When solar panels are installed on the rooftop or grounds, they provide electricity for homes and commercial properties. This way, they help reduce the reliance on grid power, leading to lower electricity bills.
• Portable Solar Chargers: Portable solar chargers, such as the Renogy E.Power 20000mAh Portable Solar Chargers help charge, help charge devices like smartphones, drones, DSLRs, tablets, etc., on the go.
• Solar Street Lighting: Solar lights like Prepare Waterproof Solar Pathway Lights provide efficient, off-grid lighting for streets and public spaces.
• Remote and Off-Grid Power: Solar cells can provide electricity to remote areas without access to and dependence on traditional power sources.
• Solar-Powered Vehicles: Photovoltaic cells can easily power cars, bikes, buses, and RVs and promote sustainable transportation solutions.

What are the types of solar cells?

Based on how solar cells work, their application, characteristics, and advantages, there are majorly four types of solar cells that are widely used. These solar cells are:

Silicon Solar Cells

There are two types of silicon solar cells: monocrystalline solar cells, which offer the highest efficiency rates of 15 - 20%, and polycrystalline solar cells, which have efficiency rates ranging from 13 - 16%. Monocrystalline solar cells are highly efficient and durable but are a little costlier than polycrystalline solar cells, which have a simpler manufacturing process.

Thin-Film Solar Cells

Thin-film solar cells are made by depositing one or more layers of photovoltaic material onto glass, metal, or even plastic. As the name suggests, these thin-film solar cells are lightweight and flexible, which makes them ideal for photovoltaics and portable solar devices. Even though thin-film solar cells have less efficiency than traditional silicon solar cells, they have an affordable production cost, which makes them an attractive option for specific usage.

Organic Solar Cells

Compared to silicon solar cells, organic solar cells use carbon-based material to convert sunlight into electricity. These solar cells offer a low production cost but have a lower efficiency rate of around 8 - 12%. According to Energy.gov, multiple research and development projects are underway for organic photovoltaics (OPV) that would help increase their efficiency.

Perovskite Solar Cells

Perovskite solar cells are also a modern counterpart to silicon-based solar cells. These solar cells use a perovskite-structured compound as an active layer that helps harvest photons. In recent laboratory-based experiments, these perovskite solar cells have achieved a 25% efficiency rate. That said, since the technology is fairly new, certain challenges exist, such as long-term stability and scalability.

Frequently asked questions about solar cells

1. What is the difference between photovoltaic cells and solar cells?

Photovoltaic cells and solar cells are common terms for devices that convert sunlight into electricity. The term 'photovoltaic' highlights the entire process of converting light (photons) into electricity (voltaic).

2. What are photovoltaic cells made of?

Most photovoltaic cells are made of semiconductor materials like silicon. These cells consist of multiple layers, including a p-type and n-type and an anti-reflective coating that enhances light absorption. Several other materials are also used in photovoltaic cells, like thin films of cadmium telluride (CdTe) or copper indium gallium selenide (CIGS).

3. What are PV cells in solar panels?

In solar panels, photovoltaic cells are the individual units responsible for converting sunlight into electricity. Each PV cell generates a small amount of electricity, but when combined in a grid-structured panel, these cells produce sufficient power to power residential homes and large-scale solar farms.

Conclusion

After getting an in-depth understanding of how solar cells work, one can easily understand how these solar cells represent a remarkable advancement in renewable energy technology. As solar power continues to grow in popularity, solar cells play an important role in reducing carbon emissions and lowering the reliance on grid power supply.

Whether for residential, commercial, or industrial applications, different types of solar cells provide a cost-effective solution that meets energy needs. If you want to invest in solar panels that are built with high-quality monocrystalline silicon solar cells and convert most of the sun's rays into electricity, you may go ahead with the Renogy 100 Watt 12 Volt Monocrystalline Solar Panels.