Polycrystalline ( Polycrystalline )
Overview and Appearance
Polycrystalline or Multicrystalline is a newer technology and varies in the manufacturing process.
The polycrystal also begins as a 'seed' of silicon crystal placed in a beaker of molten silicon. However, instead of pulling the silicon crystal seed as with Monocrystalline, the silicon cup is simply allowed to cool. This creates the distinctive edges and grains in the solar cell.
Polycrystalline cells were previously thought to be inferior to Monocrystalline because they were slightly less efficient, but because they could be produced using cheaper methods, they became the dominant technology in the residential solar panels market.
In November 2015, Trina Solar announced that it had produced a polycrystalline cell with an efficiency of 21.25%. This should allow them to produce polycrystalline modules with efficiencies of between 18-20%, a concept considered impossible until at least 2013.
The basis for the new record for P-type polycrystalline solar cells has been the continuous quality improvements of polycrystalline wafers in recent years, which have helped push standard 60-cell polycrystalline panels from 240W to 260W.
Polycrystalline is now very close to Monocrystalline cells in efficacy.
Source : www.pv-tech.org/news/trina-solar-sets-new-21.25-multicrystalline-cell-efficiency-record
Overview and Appearance
Thin-film panels are a completely different technology from Mono and Polycrystalline panels. They are a new technology compared to Mono and Polycrystalline cells and will not be considered a mature technology as vast advances in this technology are expected in the next 10 years.
A thin film panel can be described as having a solid black appearance. If the panel has no bezel, it is a thin-film panel, it may or may not have a frame.
Thin-film panels are made by depositing a photovoltaic material onto a glass-like solid surface. The photovoltaic material used is variable and combinations of more than one material have been used successfully and commercially. Examples of the most common photovoltaic materials used are:
Cadmium Telluride (CdTe)
Copper indium gallium selenide (CGIS)
Paint-sensitized solar cell (DSC)
Each of the above are known as different panel types, but they all fall under the umbrella of being Thin Film panels.
Thin-film cells have a reputation as the 'worst' of solar panel technologies because they have the lowest efficiency. However, this is because they have a lower power efficiency; this means they only need the most space for the same amount of power. As they become the cheapest panels to produce due to low material costs for thin film, they are quickly becoming economically efficient panel types.
Depending on the technology, thin-film module prototypes have reached efficiencies between 7-13% and production modules are running at about 9%. It is expected to climb to about 10-16% in future module efficiencies.
The thin-film PV market grew at an annual rate of 60% from 2002 to 2007. In 2011, close to 5% of US photovoltaic module shipments to the residential sector were based on thin film.
Advantages of polycrystalline solar panels
The process used to make polycrystalline silicon is simpler and less costly. The amount of waste silicon is less than monocrystalline.
Polycrystalline solar panels tend to have slightly lower heat tolerance than monocrystalline solar panels. Polycrystalline solar panels will tend to be more temperature efficient than solar modules made with mono cells. This means that for this type of cell, the output will drop less as the heat increases. However, in practice these differences are very small.