What is a Solar panel? – Types and How does it work

What is Solar Panel?

Solar energy begins with the sun. Solar panels (also known as “PV panels”) are used to convert light from the sun, which is composed of particles of energy called “photons”, into electricity that can be used to power electrical loads.

Definition: A solar panel, or photovoltaic (PV) module, is an assembly of photovoltaic cells mounted in a framework for installation. Solar panels can be used for absorbing the sun’s rays and convert them into electricity or heat.

A solar panel is actually a collection of solar (or photovoltaic) cells, which can be used to generate electricity through the photovoltaic effect. These cells are arranged in a grid-like pattern on the surface of solar panels.

Thus, it may also be described as a set of photovoltaic modules, mounted on a structure supporting it. A photovoltaic (PV) module is a packaged and connected assembly of 6×10 solar cells.

When it comes to wear-and-tear, these panels are very hardy. Solar panels wear out extremely slow. In a year, their effectiveness decreases only about one to two percent (at times, even lesser).

Most solar panels are made of crystalline silicon solar cells, which are the main component of natural beach sand. Silicon is abundantly available, making it the second most available element on Earth. However, converting sand into high-grade silicon comes at a high cost and is an energy-intensive process.

How do solar panels work?

Solar panels use sunlight as a source of energy and generate direct current electricity. A collection of PV modules is called a PV Panel, and a system of Panels is an Array. Arrays of a photovoltaic system supply solar electricity to electrical equipment.

We all know that photovoltaic solar panels convert sunlight into usable electricity, but few people know the real science behind the process. This week we’ll be understanding the science behind solar on the blog. It can seem complicated, but it all boils down to the photovoltaic effect; the ability of matter to emit electrons when immersed in light.

Before we get to the molecular level, let’s take a look at the basic flow of electricity generation:

How do solar panels work

Basic Steps in Solar Energy Generation and Transmission

  • Sunlight hits the solar panels and creates an electric field.
  • The generated current flows to the edge of the panel and into a conductive wire.
  • The conductive wire carries the electricity to the inverter, where it is converted from direct current to alternating current, which is used to power buildings.
  • Another cable carries the alternating current from the inverter to the electrical panel on the property (also known as a breaker box), which distributes the power throughout the building as needed.
  • The electricity that is not required for generation flows through the electricity meter into the power grid. As the current flows through the meter, the meter will reverse, attributing excessive generation to your property.

Now that we have a basic idea of how solar power is generated and flowed, let’s dig deeper into the science behind the solar photovoltaic panel.

The Science Behind Solar PV Cells

Solar PV panels are made up of many small photovoltaic cells – photovoltaics means that they can convert sunlight into electricity. These cells are made of semiconducting materials, most commonly silicon, a material that can conduct electricity while maintaining the electrical imbalance necessary to create an electric field.

Solar Panel Working

When sunlight hits the semiconductor in the solar PV cell, the light’s energy is absorbed in the form of photons, releasing a series of electrons which then drift freely around the cell. The solar cell is specially designed with positively and negatively charged semiconductors that are connected together to create an electric field.

This electric field forces the driving electrons to flow in a certain direction towards the conductive metal plates that line the cell. This flow is known as the energy flow, and the magnitude of the current determines how much electricity each cell can produce. As soon as the loose electrons hit metal plates, the current is conducted in wires so that the electrons can flow like any other power generation source.

As the solar panel generates electricity, the energy flows through a series of wires to an inverter. While solar panels generate direct current, most electricity consumers need alternating current to power their buildings. The function of the inverter is to convert the current from direct current to alternating current and make it accessible for daily use.

After the electricity has been converted into a usable state (alternating current), it is sent by the inverter to the electrical panel (also known as a circuit breaker box) and, if necessary, distributed throughout the building. The electricity is now available to power lamps, appliances, and other electrical devices with solar energy.

How are solar panels made?

Solar photovoltaic is made up of a number of parts, the main of which are silicon cells. Silicon, atomic number 14 in the periodic table, is a non-metal with conductive properties that enable sunlight to be converted into electricity.

When light interacts with a silicon cell, electrons are set in motion, causing a flow of electricity. This is known as the “photovoltaic effect”.

However, silicon cells alone cannot provide electricity for your home. They are paired with a metal case and wiring that allow the solar cell’s electrons to escape and provide useful energy.

Silicon occurs in a number of different cell structures: single cells (monocrystalline), polycrystalline or amorphous forms, which are most often associated with thin-film solar panels.

Solar panel manufacturing process

Steps to manufacture monocrystalline PV cells:

  • Silica sand is purified in an arc furnace to create 99% pure silicon
  • The 99% silicon is further refined close to 100% pure silicon
  • The silicon is doped with boron or phosphorous (P-type or N-type)
  • The doped silicon is melted and extracted into a crystalline ingot
  • The round ingot is diamond wire-cut into thin square wafers
  • The thin base wafer is coated with an ultra-thin layer of either P-type or N-type silicon to form the PN-junction.
  • An anti-reflective layer and metallic fingers are added to the cell surface
  • Flat ribbon busbars (as shown) or thin wire (MBB) busbars are added

Monocrystalline solar panels are made from a large silicon block and manufactured in silicon wafer formats. The manufacturing process involves cutting individual silicon wafers that can be mounted on a solar panel.

Monocrystalline silicon cells are more efficient than polycrystalline or amorphous solar cells. The manufacture of individual monocrystalline wafers is more labor-intensive and consequently also more expensive to manufacture than polycrystalline cells. Monocrystalline cells have a distinct black aesthetic and are often associated with the sleek appearance of SunPower’s premium panels.

Polycrystalline solar cells are also silicon cells, but instead of being formed in a large block and cut into wafers, they are made by melting several silicon crystals together. Many silicon molecules are melted and then fused back into the plate itself. Polycrystalline cells are less efficient than monocrystalline cells, but they are also less expensive. They have a bluish hue that is often associated with the aesthetics of SolarWorld solar panels.

Finally, amorphous silicon cells create flexible solar panel materials that are often used in thin-film solar panels. Amorphous silicon cells are non-crystalline and instead are attached to a substrate like glass, plastic or metal. For this reason, thin-film solar panels are true to their name: they are lean and bendable, unlike a standard panel. Though an ideal use case for versatility, amorphous solar cells are very inefficient compared to mono or polycrystalline cells. First Solar is best known for manufacturing thin-film panels in the U.S.

After the unique type of solar cell is made, solar panel manufacturers finish the process by connecting the electrical systems, adding an anti-reflective coating to the cells, and housing the entire system in a metal and glass casing.

What are the parts of a solar panel?

Solar panels are manufactured using the six major components detailed below and are assembled with the utmost precision in advanced manufacturing facilities. In this article, we will focus on modules made from crystalline silicon solar cells as these are by far the most widely used and most powerful solar technology currently available. There are other solar PV technologies such as thin film and screen printing cells, but we will not discuss these as they have limited uses or are still in development.

Six Main Components Of A Solar Panel

  • Solar photovoltaic cells
  • Toughened Glass – 3 to 3.5mm thick
  • Extruded Aluminium frame
  • Encapsulation – EVA film layers
  • Polymer rear back-sheet
  • Junction box – diodes and connectors

1. Solar PV Cells

Solar photovoltaic cells or PV cells convert sunlight directly into DC electrical energy. The performance of the solar panel is determined by the cell type and characteristics of the silicon used, with the two main types being monocrystalline and polycrystalline silicon. The base of the PV cell is a very thin wafer, typically 0.1mm thick, and is made from either a positive p-type silicon or negative n-type silicon.

There are many different cell sizes and configurations available which offer different levels of efficiency and performance including half-cut or split cells, multi-busbar (MBB) cells, and more recently shingled cells using thin overlapping wafer strips.

2. Glass

The front glass pane protects the PV cells from the weather and impacts from hail or deposits in the air. The glass is typically high-strength tempered glass with a thickness of 3.0 to 4.0 mm that can withstand mechanical loads and extreme temperature fluctuations.

The IEC minimum standard impact test requires that solar panels withstand impact from hailstones 25 mm (1 inch) in diameter at speeds up to 27 m / s. In the event of an accident or severe impact, tempered glass is also much safer than standard glass as it is more likely to break into tiny fragments than into sharp, jagged sections.

3. Aluminium Frame

The aluminum frame plays a vital role in both protecting the edge of the laminate section where the cells are located and providing solid structure to position the solar panel in. The extruded aluminum profiles are extremely light, stiff and withstand extreme loads and loads from strong winds and external forces.

The aluminum frame can be anodized in silver or black. Depending on the panel manufacturer, the corner sections can either be screwed, pressed or clamped together in order to achieve different strengths and stiffnesses.

4. EVA Film

EVA stands for “ethylene vinyl acetate”, a specially developed, highly transparent polymer layer (plastic layer) with which the cells are encapsulated and held in position during manufacture. The EVA material must be extremely durable and extremely temperature and moisture tolerant. It plays an important role in long-term performance by preventing moisture and dirt from entering.

5. Backsheet

The backsheet is the rearmost layer of common solar panels, which acts as a moisture barrier and final outer skin and offers both mechanical protection and electrical insulation. The backsheet material is made of various polymers or plastics, including PP, PET and PVF, which offer different levels of protection, thermal stability and long-term UV resistance. The backsheet level is usually white in color, but is also available as clear or black, depending on the manufacturer and module.

6. Junction Box And Connectors

The junction box is a small weatherproof housing on the back of the panel. It is necessary to securely attach the cables required to connect the panels. The junction box is important because it is the central point where all cells are connected and need to be protected from moisture and dirt.

Types of Solar Panel

There are three major types of solar panels: monocrystalline, polycrystalline, and thin-film. Each type has its own unique advantages and disadvantages, and the solar panel type best suited for your installation will depend on factors specific to your own property and desired system characteristics.

1. Monocrystalline Solar Panel

These solar panels are made using thin wafers of silicon, which are extracted from artificially grown crystals. Single crystals developed in isolation help to form these cells and make them the most efficient. This is why these are the most expensive among the other types. Compared to their counterpart polycrystalline cells, monocrystalline solar cells are about 35% more expensive and provide an efficiency rate between 15–24%.

Monocrystalline solar cell

2. Polycrystalline Solar Panel

Polycrystalline solar cells are also made using thin silicon wafers derived from artificially grown crystals, the only difference being that these are not single crystals. Rather, they use multiple interlocking silicon crystals propagated simultaneously. Therefore, their production is less expensive and they still offer an efficiency rate of 13–18%.

3. Thin film solar panel

If you’re looking for a more cost-effective option, consider thin films. Thin film solar modules are made by placing one or more films of photovoltaic material (such as silicon, cadmium or copper) on a substrate. These types of solar modules are the easiest to manufacture and, due to economies of scale, cheaper than the alternatives, as less material is required to manufacture them.

They are also flexible, which opens up many possibilities for alternative applications and is less affected by high temperatures. The main problem is that they take up a lot of space and are generally unsuitable for residential installations. In addition, they offer the shortest guarantees, as their lifespan is shorter than that of mono- and polycrystalline solar modules. However, they can be a good option to choose between the different types of solar panels that have plenty of space.

4. Amorphous Solar Panel

The cheapest form of solar cells is an amorphous solar cell. These are newly launching cells that are manufacture in a unique way. They avoid the use of crystals. Instead, their production process involves thin silicon deposits on the backing substrate.

Amorphous solar cells provide two major benefits, ie. Flexibility in solar cells with its extremely thin silicon layer, and high efficiency in low levels of light during winter.

But, while these promise the above benefits, they also compromise on efficiency. They provide the lowest efficiency rates of 7% – 9% compared to the other two variants. Thus, they require about twice the panel area to give the same output. Until now, they do not even have an approved production technology in the industry, and therefore, they are less robust than the other two types of solar panels.

5. Biohybrid Solar Panel

It is not a completely solar cell, but a hybrid solar cell is a mixture of monocrystalline solar cells and amorphous solar cells. Hybrid solar cells called HET (heterojunction with intrinsic thin layer) solar cells. Compared to each individual type of solar cell, the hybrid type is the most efficient due to the combination of the power of the two solar cells. These work best during sunny seasons, ie beyond the 250C temperature. In view of the same, this helps generates about 10% more electricity.

If one has to choose the best, polycrystalline cells prove to be the most suitable for most installations due to their value for money, design and efficiency rate.

Pros and Cons of Solar Energy System

Advantages of Solar Energy System

1. Renewable Energy Source

Among all the advantages of solar panels, the most important one is that solar energy is a truly renewable energy source. It can be used in all regions of the world and is available daily. Unlike some other energy sources, we cannot run out of solar energy.

2. Reduces Electricity Bills

Since you cover part of your energy needs with the electricity generated by your solar system, your energy costs go down. How much you save on your bill depends on the size of the solar system and your electricity or heat consumption.

3. Diverse Applications

Solar energy can be used for various purposes. They can generate electricity (photovoltaics) or heat (solar thermal energy). Solar energy can be used to generate electricity in areas with no grid access, to distill water in regions with limited supplies of clean water, and to power satellites in space.

4. Low Maintenance Costs

Solar systems generally do not require a lot of maintenance. You just need to keep them relatively clean, so cleaning them a couple of times a year is enough. When in doubt, you can always count on specialist cleaning companies to offer this service between £ 25 and £ 35. The most reliable manufacturers of solar modules offer a guarantee of 20 to 25 years.

Since there are no moving parts, there is also no wear and tear. The inverter is usually the only part that needs to be replaced after 5-10 years, as it works continuously to convert solar energy into electricity and heat (solar PV vs. solar thermal). In addition to the inverter, the cables also need to be maintained to ensure that your solar system is running at maximum efficiency.

5. Technology Development

Technology in the solar industry is constantly evolving and improvements will intensify in the future. Innovations in quantum physics and nanotechnology can potentially increase the effectiveness of solar panels and double or even triple the electrical input of solar power systems.

Disadvantages of Solar Energy System

1. Cost

The initial cost of buying a solar system is quite high. This includes paying for solar panels, inverters, batteries, wiring and installation. Nevertheless, solar technologies are constantly evolving, so it can be assumed that prices will fall in the future.

2. Weather-Dependent

Although solar energy can still be collected on cloudy and rainy days, the efficiency of the solar system decreases. Solar panels rely on sunlight to effectively collect solar energy. As a result, a few cloudy, rainy days can have a noticeable impact on the energy system. You should also take into account that solar energy cannot be collected at night.

3. Solar Energy Storage Is Expensive

Solar energy must be used immediately or can be stored in large batteries. These batteries, which are used in off-grid solar systems, can be charged during the day so that the energy is used at night. This is a good solution for using solar energy all day, but it’s also quite expensive.

In most cases it is wiser to only use solar energy during the day and take energy from the grid at night (this is only possible if your system is connected to the grid). Fortunately, your energy needs are usually higher during the day, so you can get most of it from solar energy.

4. Uses a Lot of Space

The more electricity you want to produce, the more solar panels you will need to collect as much sunlight as possible. Solar panels take up a lot of space and some roofs are not big enough to accommodate the number of solar panels that you would like.

An alternative is to install some of the panels in your yard, but they must have access to sunlight. If you don’t have enough space for all of the panels you want, you can install fewer to meet some of your energy needs.

5. Associated with Pollution

Although the pollution from solar energy systems is far less compared to other energy sources, solar energy can be associated with pollution. Transportation and installation of solar systems have been linked to greenhouse gas emissions.

FAQs.

What is solar panel?

A solar panel, or photovoltaic (PV) module, is an assembly of photovoltaic cells mounted in a framework for installation. Solar panels can be used for absorbing the sun’s rays and convert them into electricity or heat.

How do solar panels work?

Solar panels use sunlight as a source of energy and generate direct current electricity. A collection of PV modules is called a PV Panel, and a system of Panels is an Array. Arrays of a photovoltaic system supply solar electricity to electrical equipment.

How are solar panels made?

The principal steps are: Tabber and stringer: Cells are connected together Layup: Strings are positioned over the glass with a proper encapsulant foil Lamination: “Solar sandwiches” are cured in a special solar laminator to increase the lifetime of modules Framing: The frame is put around the module Testing

What are the different types of solar panels?

There are three major types of solar panels: monocrystalline, polycrystalline, and thin-film. Each type has its own unique advantages and disadvantages, and the solar panel type best suited for your installation will depend on factors specific to your own property and desired system characteristics.

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