Solar Photovoltaic Modules.

September 17, 2021 amorphous, cells, concentrators, lenses, module, modules, monocrystalline, multicrystalline, polycrystalline, power, PV, thin-film No Comments

A PV module consists of many PV cells wired in parallel to increase current and in series to produce a higher voltage. 36 cell modules are the industry standard for large power production.

The module is encapsulated with tempered glass (or some other transparent material) on the front surface, and with a protective and waterproof material on the back surface. The edges are sealed for weatherproofing, and there is often an aluminum frame holding everything together in a mountable unit. In the back of the module there is a junction box, or wire leads, providing electrical connections.

Conventionally, PV modules are designed and manufactured for outdoor applications. Thus, they can operate under the sun, rain, and other climate impacts, which make possible the use of PV modules as potential components for external enclosures of buildings.

With the development in the past few decades, various types of PV module technologies are now available in the PV market, but not all these technologies are suitable for the integration or incorporation in building envelopes, since PV modules are traditionally designed mainly for power generation, and their functionalities as envelope elements are generally overlooked.

There are currently four commercial production technologies for PV Modules:

• Single Crystalline. This is the oldest and more expensive production technique, but it's also the most efficient sunlight conversion technology available. Module efficiency averages about 10% to 12%^[*].
• Polycrystalline or Multicrystalline. This has a slightly lower conversion efficiency compared to single crystalline but manufacturing costs are also lower. Module efficiency averages about 10% to 11%^[*].
• String Ribbon. This is a refinement of polycrystalline production, there is less work in production so costs are even lower. Module efficiency averages 7% to 8%^[*].
• Amorphous or Thin Film. Silicon material is vaporized and deposited on glass or stainless steel. The cost is lower than any other method. Module efficiency averages 5% to 7%^[*]

Module electrical connections are made in series to achieve a desired output voltage or in parallel to provide a desired current capability (amperes) of the solar panel or the PV system. The conducting wires that take the current off the modules are sized according to the current rating and may contain silver, copper or other non-magnetic conductive transition metals. Bypass diodes may be incorporated or used externally, in case of partial module shading, to maximize the output of module sections still illuminated.^{[citation needed]}

Some special solar PV modules include concentrators in which light is focused by lenses or mirrors onto smaller cells. This enables the use of cells with a high cost per unit area (such as gallium arsenide) in a cost-effective way.

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Silicon - The Most Popular Material for Solar Cells.

September 16, 2021 amorphous, cell, crystalline, monocrystalline, polycrystalline, silicon, solar No Comments

Silicon - The Most Popular Material for Solar Cells.

The basic component of a solar cell is pure silicon, which has been used as an electrical component for decades as the silicon solar cell technology gained ground already in the 1950s.

Pure crystalline silicon is a poor conductor of electricity as it is a semiconductor material at its core. To address this issue, the silicon in a solar cell has impurities-meaning that other atoms are purposefully mixed in with the silicon atoms in order to improve silicon’s ability to capture the sun’s energy and convert it into electricity.

Solar cells made out of silicon currently provide a combination of high efficiency, low cost, and long lifetime. Modules are expected to last for 25 years or more, still producing more than 80% of their original power after this time.

There are mainly three types of Silicon solar cells:

MONOCRYSTALLINE		POLYCRYSTALLINE		AMORPHOUS

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Polycrystalline Silicon Solar Cells.

September 16, 2021 blue hue, cells, crystal, high temperatures, polycrystalline, silicon, solar No Comments

Polycrystalline.

In polycrystalline solar cells each PV cell is made of multiple silicon crystal fragments that are melded together during manufacturing. ;In addition, polycrystalline solar cells tend to have a blue hue instead of the black hue of monocrystalline cells.

They were the first solar cells to be developed when the industry started in the 1980s. Most interestingly, polycrystalline cells do not undergo the same cutting process as the monocrystalline cells. Instead, the silicon is melted and then poured into a square mould. This is what creates the specific shape of the polycrystalline.

One of the benefits of this process is that the solar cells become much more affordable. This is because hardly any silicon is wasted during the manufacturing process. However, they are less efficient than monocrystalline solar cells, and also require a lot more space. This is due to the fact that they have lower levels of purity than the single crystalline cell models.

Polycrystalline also has a lower tolerance for heat than monocrystalline. This means that they are unable to function as efficiently in high temperatures. This can be a massive disadvantage in areas with hot climates.

Polycrystalline silicon is normally considered less efficient than single-crystal silicon. On the other hand, polycrystalline silicon devices are less expensive to produce. The casting process is the most common means of producing polycrystalline silicon on a commercial scale.

Polycrystalline solar cells are cheaper than monocrystalline cells, however, they are less efficient and aren’t as aesthetically pleasing.

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Solar Photovoltaic Cell (also called a solar cell).

September 15, 2021 amorphous, arrays, cell, cells, crystalline, panels, photovoltaic, polycrystalline, PV, semiconductor, silicon No Comments

Solar cell, also called photovoltaic (PV) cell, any device that directly converts the energy of light into electrical energy through the photovoltaic effect. The PV cell is composed of semiconductor material. Unlike batteries or fuel cells, solar cells do not utilize chemical reactions or require fuel to produce electric power, and, unlike electric generators, they do not have any moving parts.

When the semiconductor is exposed to light, it absorbs the light’s energy and transfers it to negatively charged particles in the material called electrons. This extra energy allows the electrons to flow through the material as an electrical current.

The efficiency of a PV cell is simply the amount of electrical power coming out of the cell compared to the energy from the light shining on it, which indicates how effective the cell is at converting energy from one form to the other.

The overwhelming majority of solar cells are fabricated from silicon, with increasing efficiency and lowering cost as the materials range from amorphous (noncrystalline) to polycrystalline to crystalline (single crystal) silicon forms.

Structure and operation.

Light enters the device through an optical coating, or antireflection layer, that minimizes the loss of light by reflection; it effectively traps the light falling on the solar cell by promoting its transmission to the energy-conversion layers below. The antireflection layer is typically an oxide of silicon, tantalum, or titanium that is formed on the cell surface by spin-coating or a vacuum deposition technique.

The three energy-conversion layers below the antireflection layer are the top junction layer, the absorber layer, which constitutes the core of the device, and the back junction layer. Two additional electrical contact layers are needed to carry the electric current out to an external load and back into the cell, thus completing an electric circuit.

The electrical contact layer on the face of the cell where light enters is generally present in some grid pattern and is composed of a good conductor such as a metal. Since metal blocks light, the grid lines are as thin and widely spaced as is possible without impairing collection of the current produced by the cell. The back electrical contact layer has no such diametrically opposed restrictions. It need simply function as an electrical contact and thus covers the entire back surface of the cell structure. Because the back layer also must be a very good electrical conductor, it is always made of metal.

The amount of electricity produced from PV cells depends on the characteristics (such as intensity and wavelengths) of the light available and multiple performance attributes of the cell.

Solar cells can be arranged into large groupings called arrays. These arrays, composed of many thousands of individual cells, can function as central electric power stations, converting sunlight into electrical energy for distribution to industrial, commercial, and residential users.

Solar cells in much smaller configurations, commonly referred to as solar cell panels or simply solar panels, have been installed by homeowners on their rooftops to replace or augment their conventional electric supply. Solar cell panels also are used to provide electric power in many remote terrestrial locations where conventional electric power sources are either unavailable or prohibitively expensive to install.

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Photovoltaic Solar Technology.

September 15, 2021 arrays, cell, cells, electricity, modules, panel, panels, photovoltaic, polycrystalline, power, PV, silicon, systems No Comments

Solar cells, also called photovoltaic cells, convert sunlight directly into electricity.  Photovoltaics (often shortened as PV) gets its name from the process of converting light (photons) to electricity (voltage), which is called the photovoltaic effect. This material, usually made of silicon but potentially other polycrystalline thin films, generates a direct current when sunlight hits the panel.

A single PV device is known as a cell. An individual PV cell is usually small, typically producing about 1 or 2 watts of power. To boost the power output of PV cells, they are connected together in chains to form larger units known as modules or panels. Modules can be used individually, or several can be connected to form arrays.

Commercially available PV panels are up to 22.5% efficient at converting sunlight into electricity in optimal conditions, but even in partly cloudy weather, they can operate at 80% of their maximum output.

PV systems may or may not be connected to the electric transmission grid:

• PV systems linked to the transmission grid can supplement utilities energy supply during daylight hours, which normally include the peak energy demand periods.
• Independent PV cells can power a variety of individual items, from personal calculators and streetlights to water pumps on ranches and remote settlements far from power lines.

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