Different Types of Solar Panels and Photovoltaic Cells
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Different Types of Solar Panel and Which one is the best PV Panel for you?
If you have decided to buy solar panels for your final design, but don’t know that which one is most suitable for you? Then this article is for you and for those as well who want to know more information and detail about different kinds of Solar panels and photovoltaic cells.
If you pick the topic, you will learn:
- What are Solar panels and how they work?
- Construction of different types of Solar Panels.
- Different types of Solar panels and Photovoltaic cells (like Monocrystalline, polycrystalline, hybrid, thin film PV, Solar panel thermal etc).
- Different types of solar panels with Pros and Cons.
- Which Solar panels type is best (For home and other application)
- How much Solar panel in Watts do I need?
- Step by Step Solar Panel Installation Guide.
- Series/parallel connection of Solar panels
- Solar panel connection with batteries and UPS/Inverters.
- Solar panels design and installation ideas.
- Difference between Solar panel and Solar Cell (PV panels VS PV Cell)
- Which is the best and most suitable Solar panel for home use?
- And much more ;)
We hope that some of them will help to lead you to the right decision without any confusion to select a proper solar panel.
Now let’s begin.
Crystalline Silicon (c-Si) for PV Technology
Crystalline Silicon (c-Si) is a crystalline form of Silicon (Si) which is widely used in the manufacturing process of the crystalline solar panels (Poly and mono-crystalline PV) in the photovoltaic technology. Almost 90% of PV technology is based on Silicon which is mostly used in crystalline silicon solar panels.
There are many factors to use the silicon in photovoltaic technology but the important one is purity of silicon, which means the more purification in silicon, the more ability of the solar panel to convert sunlight into electricity as output power.
Crystalline Silicon (c-Si) forms the basis of poly or multi and monocrystalline Silicon PV cells, which we will discuss in detail as follow.
Monocrystalline Solar Panels
“Mono” means “single”, as the name indicates, The Monocrystalline solar panel cells are made of single pure silicon crystal. It is also called single crystalline silicon because once single crystal used to make the array which provides Solar Panel (PV) purity and uniform appearance across the PV Module.
Monocrystalline Solar panels (PV cells) are in rounded shape and the Silicon crystal bars look like cylindrical in the entire PV module.
Good to Know:
To differentiate between Polycrystalline and Monocrystalline PV (Photovoltaic or Solar panel) is that monocrystalline solar cells look cylindrical with rounded edges.
- The efficiency of Monocrystalline Solar panels are 15-20%, while the latest monocrystalline solar panels achieves 25% efficiency in the labs and 21% is the verified efficiency. In the US, the efficiency of the E20 Series is approximate up to 20% and the X-Series of SunPower PV (Photovoltaic panels) provides 21.5% efficiency.
- Monocrystalline PV (Photovoltaic or Solar panels) requires the least amount of space and takes up a small area on the roof.
- The average life of Monocrystalline solar panels are about 25 years while other PV panels manufacturers claims 25 to 30 year life expectancy.
- Its performance is better than polycrystalline at same rating light conditions. In addition, monocrystalline solar panels produce up to four times the amount of Electrical energy as compared to thin film solar panels.
- In short, Monocrystalline Solar panels are the most efficient available PV module, most popular technology in the market, commonly available, takes up the least amount of area on the roof and easy to use and replace.
- Monocrystalline solar panels are costly. The initial cost of monocrystalline PV panels is too high and expensive as compared to thin film solar PV modules or Polycrystalline Solar panels.
- As it is made of single silicon crystal, hence the partially covered area of solar panel with snow, dirt or shade may break the entire circuit of PV.
- A large amount of pure silicon ends up as waste. To make silicon wafers and arrays in large cylindrical shape (a process, which used to make monocrystalline Silicon in called Czochralski process), the four ends of the PV cells are cut out of the ingots, which result in large amount of pure Silicon waste.
- It tends to be more efficient when the temperature goes up i.e., it works better in warm weather and full sunshine, but it is not a considerable fact for most homeowners.
Polycrystalline solar panels
“Poly” means “many or multi”. As the name tells the story, it is made of a number of different pure silicon crystals, combined together to make a solar or PV cell. The shapes of these cells are rectangular and need less silicon as compared to monocrystalline solar panels which makes them less expensive, but their efficiency is also lower than the monocrystalline PV cells (approximately 13.5-17%. It is also called polysilicon or multi-crystalline silicon and first introduces in 1981 in the market.
To make Polycrystalline PV (photovoltaic) cells, pure raw silicon is melted and poured into a square mold which is cooled and cut into perfectly squared wafers and arrays. There is a random crystal arrangement Polycrystalline solar panel and reflect some light back, so it looks a little bluer. Nowadays, the prices of Polycrystalline solar panels come down and get popularity again in the US, UK, Australia and other local markets.
- Polycrystalline solar panels have lower heat tolerance (which means their performance is lower in high temperature as compared to monocrystalline solar PV modules. As heat may disturb the solar panels and reduce their life). However, it is not considerable fact to most homeowners and Solar panel buyers and they don’t take into account while design the solar panel installation layout.
- The process to produce the polycrystalline silicon is cost less and less complicated.
- In short, it is cost effective to manufacture, good efficiency, takes up a small area on the roof, commonly available and easy to replace and use.
- The efficiency of polycrystalline solar panels is approximately 13.5-17%. This technically means that if 100W of solar potential energy strikes the solar panel, then its output would be about 13.5W to 17Watts solar produced electrical energy. Hence, it is slightly less efficient than monocrystalline solar panel.
- The same surface of polycrystalline PV modules (in size) would produce less power as compare to monocrystalline solar panel (but this is not always the case).
- It is not suitable to use as compared to thin film and monocrystalline solar panel in terms of elegance (when needed) because it hasn’t a uniform appearance, but only random and odd blue color.
String Ribbon Solar Cells
A process in which multi crystalline silicon strips and foils are manufactured for Photovoltaic (PV) Technology. In this process, high temperature resistance wires are pulled through the molten silicon to form multi –crystalline thin ribbon of silicon crystals. These very thin ribbons then cut into different lengths to form PV and Solar cells. Solar panels made with String Ribbon technology looks the same to traditional polycrystalline PV panels. The process was first developed in the 1970s by Mobil-Tyco, Solar Energy Corp and The Evergreen Solar were the major manufacturer of using String ribbon Technology to make the solar cells. Note that Note that String Ribbon PV panels are also made out of polycrystalline silicon.
- Lower cost production, simple and easy to use.
- String Ribbon Solar panels efficiency is about 13-14% (while in laboratories, researchers achieved 18-19% Efficiency)
- Manufacturing is more energy extensive
- Lowest space-efficiency
Thin Film Solar Cells (TFSC) or (TFPV)
Thin Film Solar Cells (TFSC) are also known as Thin Film Photovoltaic Cells (TFPV) or Amorphous PV Modules.
Integrating one or more thin layers of PV materials or thin film (TF) on a substrate, e.g. metal, glass, plastic etc. is the basic process to make thin film solar panels and it is a second generation solar cell. The thickness of film varies from a few nanometers (nm) to tend of micrometers (µm) while the much thinner of thin film has been developed. The first generation Crystalline Silicon solar cell (c-SI) uses up to 200 µm silicon wafers.
Following are the subcategories (Types of Thin Film Solar panels) by which PV materials are integrated on a substrate.
- Amorphous Silicon (a-Si/TF-Si)
- Copper Indium Gallium Selenide (CIGS/ CIS)
- Cadmium Telluride (CdTe)
Below are the third generation thin film solar cells, which are not available commercially at all and researcher are hopeful to make the dream come true (very soon).
- Organic Photovoltaic Cells (OPC/OPC) … (It is available now)
- Polymer solar cells
- Quantum dot
- Copper Zinc Tin Sulfide,
- Perovskite Solar Cells
Thin film solar panels are cheaper but less efficient than conventional Crystalline Silicon solar cell (c-SI) technology. However, recent technology development verifies the lab cell efficiency of Cadmium Telluride (CdTe) and Copper Indium Gallium Selenide (CIGS/ CIS) reached up to 20%.
- The Large scale production of thin film solar panels are less complicated than crystalline based PV cells.
- They are cheap as compared to other monocrystalline PV / Solar panels.
- The uniform appearance of thin film solar panels are more attractive and can be used for beautification purpose as well.
- It comes also in flexible form which may be used for many purposes and applications and make sense when used where space is not an issue.
- It has high temperature tolerance, i.e. high temperature and shading have less impact on thin film solar panels.
- It requires a lot of space. Typically, they are not useful for residential and homeowners.
- The additional support structure, cables, maintenance, etc. for thin film solar panel installation makes the system costly.
- The overall life expectancy of thin solar panels is lower than that of poly- and monocrystalline solar panels.
Amorphous silicon (a-Si or a-Si:H) Solar Cells and PV Modules
An amorphous silicon solar cell which is a subcategory of Silicon thin film solar panels has recently become popular in the market. As they need less than (say 1%) of Silicon used in the crystalline solar cells and very less efficient than poly or monocrystalline solar panels (approx 5-6%).
To manufacture an amorphous silicon solar cell one or more layers of photovoltaic materials are sandwiched onto a substrate as a gas spray which is called “vapour deposition”.
Cadmium Telluride (CdTe) Solar Cells
Cadmium Telluride thin film solar panels are based on Cadmium telluride and the only PV (Photovoltaic) technology, which is cost effective as compared to Silicon crystalline solar panels in a significant part of the market especially in the multi kilowatt system.
The efficiency of these solar panels tends to be in range between 9-11%.
First Solar has installed over 5 gigawatts (5GW) of cadmium telluride thin-film solar panels worldwide. The same company holds the world record for CdTe PV module efficiency of 14.4%.
Update: in August 2014, First Solar announced a device with 21.0% conversion efficiency. In 2014, the record module efficiency was also raised by First Solar from 16.1% up to 17.0%
The first solar powered 40-MW (CdTe) PV (Photovoltaic) Array installed by JUWI Group in Brandis, Germany.
Copper Indium Gallium Selenide (CIGS/ CIS) Solar Cells
The commercial production of flexible Copper Indium Gallium Selenide PV cells started in Germany in 2011. They are made of Copper, Indium, Gallium and Selenide by integrating on a substrate like plastic or glass, along with anode and cathode (electrodes) on the back and front side to collect electrical output power. CIGS or CIS solar panel cells have high temperature tolerance and work better in a warm climate, so they work even better when cells deposited on glass.
The efficiency rates for CIGS solar panels typically operate in the range 11-14 %. However, the highest value achieved by National Renewable Energy Laboratory researcher team is 19.9% and again the best efficiency achieved as of October 2013 was 20.8%. In addition, scientists at EMPA, (Swiss Federal Laboratories for Materials Science and Technology) developed CIGS cells on flexible polymer foils with a new record efficiency of 20.4%.
Expect this, many other thin film solar panels are still in the research and gradually growing the development. You may hear more unexpected and interesting news about these developments soon in coming daysJ.
BIPV: Building Integrated Photovoltaic Panels
This is not something new, but the same as they may be thin film or Silicon crystalline solar panels or both, in the shape of roof tiles or what the design needs to be. BIPV (Building Integrated Photovoltaic) is designed to be a part of a building like walls, roofs, facades, windows and other things which may fit with photovoltaic materials (Solar Shingles are the best example Building Integrated Photovoltaic [BIPV]). It looks very nice and beautiful, but beautiful things are expensive too ;).
Unfortunately, Building Integrated Photovoltaic BIPV is too much expensive system and less efficient as well as compared to other PV (photovoltaic) cells and Panels. So it is not recommended to homeowners or small scale users to integrate BIPV systems as they are used in huge projects like a 10MW plant in the desert near Las Vegas.
Solar Thermal Panels
It is a different PV or Solar power system rather than the explanation above. They do not produce the electricity, but convert the solar power into required heat to heat up the water for swimming pool or general purpose usage at home. It is also good to know that some solar thermal or PV panels can even be used for heat and air-conditioning too.
Hybrid Solar Cells and PV Panels
An Organic material (a Semiconductor material which properties lay between in insulator and conductors and used for electrical conductivity) is sandwiched with an inorganic high electron conduction material to form the photovoltaic (PV) layers. Which efficiency is greater than the single material layer and has both the advantages of organic and inorganic semiconductor masteries.
The hybrid PV cells are low cost by R2R process (roll-to-roll or Real-to-Real process: creating electronic components and devices on a flexible plastic roll or metallic sheet and foils) and developing solar power conversion as well.
The most efficient hybrid solar panels available are Panasonic (formally Sanyo) HIT PV module with Incredible 18.6% efficiency, which takes less space on the roof as well.
Hybrid solar panels are very expensive then poly or monocrystalline PV panels. If you have a lot of space on your roofs, then it is not recommended to use the hybrid solar panel system otherwise you are wasting your money to generate the same electrical power as you generate with crystalline solar panels.
Which is the best type of Solar Panel for Home Use?
This would be a little bit difficult to decide which one is the best solar panel for you and if you don’t know even the basic about PV, then it is recommended to contact an expert to select the best one solar panel for your particular situation, but will discuss the typical matter and you will be able to get a little bit idea which may help you to select the best one solar panel for your home use.
As it depends on lots of factors such as load requirements, environment and region for peak sunshine hours and types of batteries used as backup power etc. Except all these, Monocrystalline solar panels are best other than polycrystalline solar panels in efficiency but they are little bit costly as compared.
As we know that “Cost and space” is the main factors for proper PV panel selection, so we will briefly discuss the topic.
As the majority of us haven’t large space on their roof, windows etc, than thin film solar panel are not for you. Obliviously, but crystalline base solar panels in the best choice then, and if size really matter, then go for the highest rated out power solar panels because the same sizes PV panels have the different rating such as 60W, 150W, 200W etc.
If size matter, Then which one is best? Mono or Poly crystalline Solar panel
Both are good for you with the same advantages except that monocrystalline solar panels are more space efficient and produce little more electrical power than polycrystalline but this is not always the case.
One thing more that polycrystalline solar panels are slightly less expensive, but also less space efficient as well.
In addition, for the same rating (say 150W) of mono and polycrystalline solar panels would generate approximately the same electrical output power (with a few negligible difference) but polycrystalline would take up little more space as compared to mono-crystalline solar panel.
Now it depends on you that for which one you go for.
PV panel prices are typically listed as Cost per Watt ($/Watt). If you want to go for the cheapest price per rated power, then you would have to compare the prices of different available mono and polycrystalline solar panels available in the market and internet. For example, the Talesun Solar panel (model is TP660P-235) is the cheapest PV panel and rated about 235W with the price of $183. So the price per Watt becomes $0.75. On the other hand, the EcoSolargy solar panel (ECO230S156P-60) is a more expensive PV panel and its rating is 230W with the price of per watt of about $1.
Out Put is King
PV manufacturers give warranty on the Solar panels about 25-30 years. But keep in mind that the performance of solar panels gradually degrades over the time and overall performance remains 80% when it’s near to expire. Therefore, don’t compromise on Solar panels output power and leave your designed solar panel installation system reliable. Again! Don’t go for cheap PV panels otherwise you will have to pay the price once again :P.
Now! It is your turn.
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