Solar panel

          A solar cell panel, solar electric panel, photo-voltaic (PV) module or solar panel is an assembly of  photovoltaic cells mounted in a framework for generating energy. Solar panels use sunlight as a source of energy to generate direct current electricity . A collection of PV modules is called a PV panel, and a system of PV panels is called an array. Arrays of a photovoltaic system supply solar electricity  to electrical equipment.

Theory and construction

           modules use light energy from the Sun to generate electricity through the photovoltaic effect . Most modules use wafer-based crystal cells or thin film cell. The structural member of a module can be either the top layer or the back layer. Cells must be protected from mechanical damage and moisture. Most modules are rigid, but semi-flexible ones based on thin-film cells are also available. The cells are usually connected electrically in series, one to another to the desired voltage, and then in parallel to increase current. The powerof the module is the mathematical product of the voltage  and the current  of the module. The manufacturing specifications on solar panels are obtained under standard conditions, which is not the real operating condition the solar panels are exposed to on the installation site.

A PV junction diode  is attached to the back of the solar panel and functions as its output interface. External connections for most photovoltaic modules use MC4 connectors  to facilitate easy weatherproof connections to the rest of the system. A USB power interface can also be used.^[7] Solar panels also use metal frames consisting of racking components, brackets, reflector shapes, and troughs to better support the panel structu

  

Smart solar modules

Several companies have begun embedding electronics into PV modules. This enables performing MPPT for each module individually, and the measurement of performance data for monitoring and fault detection at module level. Some of these solutions make use of power  a DC-to-DC converter technology developed to maximize the power harvest from solar photovoltaic systems. As of about 2010, such electronics can also compensate for shading effects, wherein a shadow falling across a section of a module causes the electrical output of one or more strings of cells in the module to fall to zero, but not having the output of the entire module fall to zero.

Smart modules are a type of solar panel that has a power  embedded into the solar module at the time of manufacturing. Typically the power optimizer is embedded in the junction box  of the solar module. Power optimizers attached to the frame of a solar module, or connected to the photovoltaic circuit through a connector, are not properly considered smart modules.

Smart modules are different from traditional solar panels because the power electronics embedded in the module offers enhanced functionality such as panel-level maximum power point tracking  monitoring, and enhanced safety.

Different types of solar panels have varying costs

The manufacturing processes differ between monocrystalline, polycrystalline, and thin-film; as such, each type of panel comes with a different price tag.

Monocrystalline solar panels: the highest cost option

Of all types of solar panels, monocrystalline panels are likely to be the most expensive option. This is largely due to the manufacturing process – because the solar cells are made from a single silicon crystal, manufacturers have to absorb the costs of creating these crystals. This process, known as the Czochralski process, is energy-intensive and results in wasted silicon (that can later be used to manufacture polycrystalline solar cells). 

        

Polycrystalline solar panels: middle of the road

Polycrystalline solar panels are typically cheaper than monocrystalline solar panels. This is because the cells are produced from silicon fragments rather than a single, pure silicon crystal. This allows for a much simpler cell manufacturing process, thus costing less for manufacturers and eventually end-users.

Thin-film solar panels: it depends!

What you pay for thin-film solar panels will largely depend on the type of thin-film panel; CdTe is generally the cheapest type of solar panel to manufacture, while CIGS solar panels are much more expensive to produce than both CdTe or amorphous silicon. 

Regardless of the cost of the panel themselves, the overall cost of a thin-film solar panel installation may be lower than solar panel system due to additional labor requirements. Thin-film solar panel installations are less labor-intensive because they are lighter weight and more maneuverable, making it easier for installers to carry panels up onto rooftops and secure them in place. This means reduced labor costs, which can help contribute to an overall less expensive solar installation. 

        

Monocrystalline solar panels: the most efficient option

If you see a solar panel with black cells, it’s most likely a monocrystalline panel. These cells appear black because of how light interacts with the pure silicon crystal.

While the solar cells themselves are black, monocrystalline solar panels have a variety of colors for their back sheets and frames. The back sheet of the solar panel will most often be black, silver or white, while the metal frames are typically black or silver. 

Polycrystalline solar panels: can be a more cost effective option

Unlike monocrystalline solar cells, polycrystalline solar cells tend to have a bluish hue to them due to the light reflecting off the silicon fragments in the cell in a different way than it reflects off a pure monocrystalline silicon wafer. 

Similar to monocrystalline, polycrystalline panels have different colors for back sheets and frames. Most often, the frames polycrystalline panels are silver, and the back sheets are either silver or white.

Thin-film solar panels

The biggest differentiating aesthetic factor when it comes to thin-film solar panels is how thin and low-profile the technology is. As their name suggests, thin-film panels are often slimmer than other panel ty[es. This is because the cells within the panels are roughly 350 times thinner than the crystalline wafers used in monocrystalline and polycrystalline solar panels. 

It’s important to keep in mind that while the thin-film cells themselves may be much thinner than traditional solar cells, an entire thin-film panel may be similar in thickness to a monocrystalline or polycrystalline solar panel if it includes a thick frame. There are adhesive thin-film solar panels that lie as-close-as-possible to the surface of a roof, but there are more durable thin-film panels that have frames up to 50 millimeters thick.   

      

Monocrystalline and polycrystalline solar panels 

Of all panel types, monocrystalline panels typically have the highest efficiencies and power capacity. Monocrystalline solar panels can reach efficiencies higher than 20 percent, while polycrystalline solar panels usually have efficiencies between 15 to 17 percent.

Monocrystalline solar panels tend to generate more power than other types of panels not only because of their efficiency but because they have come in higher wattage modules as well. Most monocrystalline solar panels come with more than 300 watts (W) of power capacity, some now even exceeding 400 W. Polycrystalline solar panels, on the other hand, tend to have lower wattages.