Types of Solar Panels

Types of Solar Panels


In this article related to types of solar panels, we tries to cover all information related to the basic types of solar panel available or will be available in future. Here all the important aspects related to types of solar panels are noted and briefly explained. we also classified  solar panels according  to technology and materials uses into manufacturing solar panels.


Thin Film Technology


          A thin-film solar cell , also called a thin-film photovoltaic cell, is a second generation solar cell that is made by depositing one or more thin layers, or thin film of photovoltaic material on a substrate, such as glass, plastic or metal. Thin-film solar cells are commercially used in several technologies, including cadmium telluride , copper indium gallium diselenide, and amorphous and other thin-film silicon.

Film thickness varies from a few nanometers to tens of micrometers, much thinner than thin-film’s rival technology, the conventional, first-generation crystalline silicon solar cell , that uses silicon wafers of up to 200 µm. This allows thin film cells to be flexible, resulting in lower weight, less drag and limited resistance to foot traffic

Thin-film has always been cheaper but less efficient than conventional c-Si technology. However, they significantly improved over the years, and lab cell efficiency for CdTe and CIGS reached almost 20 percent and are on par with polysilicon, the dominant material, currently used in most PV installations. Despite these facts, market-share of thin-film never reached more than 20 percent in the last two decades and has been declining in recent years to about 9 percent of worldwide photovoltaic production in 2013

Cadmium Telluride Thin Film

           Cadmium telluride  is the predominant thin film technology. With about 5 percent of worldwide PV production, it accounts for more than half of the thin film market. The cell’s lab efficiency has also increased significantly in recent years and is on a par with CIGS thin film and close to the efficiency of multi-crystalline silicon as of 2013.Also, CdTe has the lowest Energy payback time of all mass-produced PV technologies, and can be as short as eight months in favorable locations.[1]:31 A prominent manufacturer is the US-company First Solar based in Tempe, Arizona, that produces CdTe-panels with an efficiency of about 14 percent at a reported cost of $0.59 per watt.

Although the toxicity of cadmium may not be that much of an issue and environmental concerns completely resolved with the recycling of CdTe modules at the end of their life time, there are still uncertainties and the public opinion is skeptical towards this technology.

Copper Indium Gallium Selenide Thin Film

             A copper indium gallium selenide solar cell or CIGS cell uses an absorber made of copper, indium, gallium, selenide , while gallium-free variants of the semmiconductor material are abbreviated CIS. It is one of three mainstream thin-film technologies, the other two being cadmium telluride and amorphous silicon, with a lab-efficiency above 20 percent and a share of 2 percent in the overall PV market in 2013.

In 2008, IBM and Tokyo Ohka Kogyo Co., Ltd. announced they had developed a new, non-vacuum, solution-based manufacturing process for CIGS cells and are aiming for efficiencies of 15% and beyond.As of September 2014, current conversion efficiency record for a laboratory CIGS cell stands at 21.7%.

Amorphous Silicon Thin Film

             This type of thin-film cell is mostly fabricated by a technique called plasma-enhanced chemical vapor deposition. It uses a gaseous mixture of silane  and hydrogen to deposit a very thin layer of only 1 micrometre  of silicon on a substrate, such as glass, plastic or metal, that has already been coated with a layer of transparent conducting oxide. Other methods used to deposit amorphous silicon on a substrate include sputtering and hot wire techniques.

a-Si is attractive as a solar cell material because it’s an abundant, non-toxic material. It requires a low processing temperature and enables a scaleable production upon a flexible, low-cost substrate with little silicon material required. Due to its bandgap of 1.7 eV, amorphous silicon also absorbes a very broad range of the light spectrum, that includes infrared and even some ultraviolet and performs very well at weak light. This allows the cell to generate power in the early morning, or late afternoon and on cloudy and rainy days, contrary to crystalline silicon cells, that are significantly less efficient when exposed at diffuse and indirect daylight.

However, the efficiency of an a-Si cell suffers a significant drop of about 10 to 30 percent during the first six months of operation. This is called the Staebler-Wronski effect a typical loss in electrical output due to changes in photoconductivity and dark conductivity caused by prolonged exposure to sunlight


Crystalline Silicon Technology


        Crystalline silicon encompasses the crystalline forms of silicon and is an umbrella term for polycrystalline silicon and monocrystalline silicon , the two dominant semiconducting materials used in photovoltaic technology for the production of solar cells, that are assembled into a solar panel and part of a photovoltaic system to generate solar power from sunlight.

Solar cells made of crystalline silicon are often called conventional or traditional solar cells as they account for the very greatest part of worldwide PV production and were first developed more than half a century ago at Bell Labs. They are also called first generation or wafer-based solar cells, as c-Si solar cells are made of about 160 µm thick solar wafers — slices from bulks of solar grade silicon. Solar cells made from c-Si are always single-junction cells and are more efficient than their rival technologies.

Monocrystalline Silicon Solar Panel

            It consists of silicon in which the crystal lattice of the entire solid is continuous, unbroken to its edges, and free of any grain boundaries.In 2013, monocrystalline solar cells had a market-share of 36 percent, that translated into the production of 12,600 megawatts of photovoltaic capacity,and ranked second behind the somewhat cheaper sister-technology of polycrystalline silicon.

Lab efficiencies of 25.0 percent for mono-Si cells are the highest in the commercial PV market, ahead of polysilicon with 20.4 percent and all established thin-film technologies namely, CIGS cells (19.8%), CdTe cells (19.6%), and a-Si cells (13.4%).

Solar module efficiencies—which are always lower than those of their corresponding cells—crossed the 20 percent mark for mono-Si in 2012; an improvement of 5.5 percent over a period of ten years. The thickness of a silicon waver used to produce a solar cell also decreased significantly, requiring less raw material and therefore less energy for its manufacture. Increased efficiency combined with economic usage of resources and materials was the main driver for the price decline over the last decade.

Polycrystalline Silicon Solar Panel

         Polycrystalline phases are composed of a number of smaller crystals or crystallites. Polycrystalline silicon is a material consisting of multiple small silicon crystals. polycrystalline cell have efficiency of 20.4% and market share of about 54.9% of all solar panel market which is highest then any other technology of solar pannel. polycrystalline is little cost effective then monocrystalline technology and it have highest market share in all solar panel industries which is about 57%.

Concentrated Photovoltaic Solar Panel


                     Concentrated photovoltaic  technology uses optics such as lenses or curved mirrors to concentrate a large amount of sunlight onto a small area of solar photovoltaic  cells to generate electricity. Compared to regular, non-concentrated photovoltaic systems, CPV systems can save money on the cost of the solar cells, since a smaller area of photovoltaic material is required. Because a smaller PV area is required, CPVs can use the more expensive high-efficiency tandem solar cells. To get the sunlight focused on the small PV area, CPV systems require spending extra money on concentrating optics (lenses or mirrors) and sometimes solar trackers, and cooling systems. Because of these extra costs, CPV is far less common today than non-concentrated photovoltaics. However, ongoing research and development is trying to improve CPV technology and lower costs

Low concentration PV (LCPV)
Low concentration PV are systems with a solar concentration of 2-100 suns.For economic reasons, conventional or modified silicon solar cells are typically used, and, at these concentrations, the heat flux is low enough that the cells do not need to be actively cooled. The laws of optics dictate that a solar collector with a low concentration ratio can have a high acceptance angle and thus in some instances does not require active solar tracking”.

Medium concentration PV(MCPV)
From concentrations of 100 to 300 suns, the CPV systems require two-axes solar tracking and cooling (whether passive or active), which makes them more complex”.

High concentration photovoltaics (HCPV)
High concentration photovoltaics (HCPV) systems employ concentrating optics consisting of dish reflectors or fresnel lenses that concentrate sunlight to intensities of 1000 suns or more.”


Other Solar Panel Technology


Dye-Sensitized Solar Panel

                 A dye-sensitized solar cell  is a low-cost solar cell belonging to the group of thin film solar cells. DSSCs are currently the most efficient third-generation solar technology available. Other thin-film technologies are typically between 5% and 13%, and traditional low-cost commercial silicon panels operate between 14% and 17%. This makes DSSCs attractive as a replacement for existing technologies in “low density” applications like rooftop solar collectors, where the mechanical robustness and light weight of the glass-less collector is a major advantage. They may not be as attractive for large-scale deployments where higher-cost higher-efficiency cells are more viable, but even small increases in the DSSC conversion efficiency might make them suitable for some of these roles as well.

                The major disadvantage to the DSSC design is the use of the liquid electrolyte, which has temperature stability problems. At low temperatures the electrolyte can freeze, ending power production and potentially leading to physical damage. Higher temperatures cause the liquid to expand, making sealing the panels a serious problem. Another disadvantage is that costly ruthenium dye, platinum catalyst and conducting glass or plastic contact are needed to produce a DSSC. A third major drawback is that the electrolyte solution contains volatile organic compounds , solvents which must be carefully sealed as they are hazardous to human health and the environment.

Biohybrid Solar Panel

                  A biohybrid solar cell is a solar cell made using a combination of organic matter  and inorganic matter. Biohybrid solar cells have been made by a team of researchers at Vanderbilt University.it uses of photosynthesis to obtain a greater efficiency in solar energy conversion.

                The biggest advantage the biohybrid solar cell has is the way it converts solar energy to electricity with almost 100% percent efficiency. This means that almost no power is lost through the conversion of chemical to electrical power. These numbers are great compared to only a 40% efficiency traditional solar cells. Cost is also a lot less for producing biohybrid because extracting the protein from spinach and other plants is cheaper compared to the cost of metals needed to produce other solar cells.

           While the efficiency of the biohybrid cells are much greater they also have many disadvantages. In many cases some solar cells have the advantages over a biohybrid solar cell. For one, traditional solar cells produce more power than those currently being achieved by biohybrid cells. The lifespan of biohybrid solar cells is also really short lasting from only a few weeks to about nine months. The durability of the cells prove to be an issue since current solar cells can for many years.

Multijuction Solar Panel

                Multi-junction (MJ) solar cells are solar cells with multiple p–n junctions made of different semiconductor materials. Each material’s p-n junction will produce electric current in response to different wavelengths of light. The use of multiple semiconducting materials allows the absorbance of a broader range of wavelengths, improving the cell’s sunlight to electrical energy conversion efficiency.

                Traditional single-junction cells have a maximum theoretical efficiency of 34%. Theoretically, an infinite number of junctions would have a limiting efficiency of 86.8% under highly concentrated sunlight.Currently, the best lab examples of traditional silicon solar cells have efficiencies around 25%, while lab examples of multi-junction cells have demonstrated performance over 43%.

               Commercial examples of tandem, two layer, cells are widely available at 30% under one-sun illumination, and improve to around 40% under concentrated sunlight. However, this efficiency is gained at the cost of increased complexity and manufacturing price. To date, their higher price and higher price-to-performance ratio have limited their use to special roles, notably in aerospace where their high power-to-weight ratio is desirable.

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