Solar Photovoltaic Arrays.

September 17, 2021 array, arrays, modules, panels, photovoltaic, power, PV, solar, system No Comments

A photovoltaic array is the complete power-generating unit, consisting of any number of PV modules and panels.

A photovoltaic array is therefore multiple solar panels electrically wired together to form a much larger PV installation (PV system) called an array, and in general the larger the total surface area of the array, the more solar electricity it will produce.

A PV Array consists of a number of individual PV modules or panels that have been wired together in a series and/or parallel to deliver the voltage and amperage a particular system requires. An array can be as small as a single pair of modules, or large enough to cover acres.

12 volt module is the industry standard for battery charging. Systems processing up to about 2000 watt-hours should be fine at 12 volts. Systems processing 2000 - 7000 watt-hours will function better at 24 volt. Systems running more than 7000 watt-hours should probably be running at 48 volts.

The term solar array is often also used to describe large-scale solar farms, however, it can be used to describe just about any grouping of solar panels.

The size of a photovoltaic array can consist of a few individual PV modules or panels connected together in an urban environment and mounted on a rooftop, or may consist of many hundreds of PV panels interconnected together in a field to supply power for a whole town or neighborhood. The flexibility of the modular photovoltaic array (PV system) allows designers to create solar power systems that can meet a wide variety of electrical needs, no matter how large or small.

It is important to note that photovoltaic panels or modules from different manufacturers should not be mixed together in a single array, even if their power, voltage or current outputs are nominally similar. This is because differences in the solar panels I-V characteristic curves as well as their spectral response are likely to cause additional mismatch losses within the array, thereby reducing its overall efficiency.

Read More

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.

Read More

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.

Read More