Types of Solar Panels have increased manifold with the surging global solar demand fueled by falling prices of solar panels/modules.Note Solar Panels prices would have fallen by around 75% in 3 years which is a record for any energy let alone solar energy.This has made Solar Electricity on par with Electricity prices in a number of places globally.The number of manufacturers of solar panels too has increased drastically particularly in China and Asia.The range of technologies being used to made solar panels has also increased in tandem.However polycrystalline silicon solar panels continues to be the king of solar panels accounting for a lion’s share of solar panels produced globally (around 75% according to my estimates).Each Solar Panel Technology differs from others in terms of efficiency and price.They also differ in their electricity production capabilities depending on temperature.They also differ in weight and flexibility.The Sizes of Solar Panels are also quite different and different powered solar panels are required for different applications.For a small power need like charging a mobile phone only a 5-20 watt solar panel would do while for powering a solar house you would need a number of 200-300 watt solar panels.
Here are the main types of Solar Panels.
Silicon Solar Panels
- Amorphous Silicon – Amorphous Silicon (a-Si) is the smaller cousin of the Polycrystalline Solar Panels ,the main difference being the amount of silicon being used on top of the glass substrates.Amorphous Silicon uses a fraction of the Silicon that is normally used in silicon solar panels.This means that the weight and cost of the solar panel is lower however the efficiency is also much lower.Earlier this technology has a lot of backers but after Applied Materials the biggest semiconductor equipment company abandoned this technology,most a-Si companies have gone under.However some companies like Sharp,Astroenergy are still backing this technology.Oerlikon the Swiss company has made improvement like introducing tandem junction to increase the efficiency.
- Microcrystalline Tandem solar panels- A new generation of microcrystalline tandem solar panels with far higher efficiency than the amorphous type has been developed in the past 2-3 years.The substrate for the tandem type is identical in size to the substrate for the amorphous type.The microcrystalline tandem solar cell consists of a microcrystalline solar cell placed on top of a conventional amorphous solar cell.Companies like Sharp,Mitsubishi are selling such types of solar panels in the 50-150 Watt range.
- Polycrystalline Silicon Solar Panels – Polycrystalline Solar Panels are the most used Solar Panels on the planet.These Solar Panels are made out of Polycrystalline silicon which can be as much as 99.9999% pure (also known as 4N pure,the 4 denotes the number of 9s after the decimal point).Polysilicon was primarily used by the semi industry till 5-6 years ago and the electronic industry used 9N pure polysilicon.These panels have an efficiency of between 13%-17% depending on the quality of the Solar Cells being used.When you go out to buy normal solar panels,this is the solar panel that you will typically get from your solar panel retailer.Note they are available in a wide variety of power ratings going from as low as 5 watts to 250 watts or more.Its possible to buy very cheap Polycrystalline Solar Panels due to the Solar Oversupply in the market.
- Monocrsytalline Silicon Solar Panels – Monocrystalline Silicon Solar Panels give the highest efficiency and have the highest costs of production as well.During Polysilicon Manufacturing,its possible to grow pure silicon made of a single crystal.The solar panels made out of this single crystal of pure silicon is called monocrystalline solar panel.Solar Cells Efficiency can vary from 18% to 24% for the normal monocrystalline silicon technology.Sunpower makes the highest efficiency crystalline solar cells on a commercial scale.Sanyo is the other company which makes the most efficient Monocrystalline cells .Suniva is challenging the two with a low cost process for making high efficiency monocrystalline solar cells.
Non Silicon Solar Panels
- Cadmium Tellerium (Cd-Te) Solar Panels - These solar panels are produced by the largest solar panel selling company First Solar.Other companies like GE and Abound Solar are also trying to produce solar panels using this technology.While concerns were raised about usage of Cadmium which is toxic,NREL has verified that the Cd-Te compound does not pose any danger to humans and environment.Note Cd-Te Solar Panels are cheaper than silicon solar panels as they have lower efficiency (which means they need more area to generate the same amount of electricity).These types of solar panels were earlier used mostly in ground mounted solar farms.However with increasing efficiency they are being sold for installation of residential and commercial rooftops (FS-3) as well.This technology has around 12% efficiency though GE has said that it has managed to attain 15% efficiency on commercial glass.Don’t know how much of it is true since First Solar only manages around 12% efficiency despite around 10 years of dedicated R&D.
- Copper Indium Gallium Diselenide (CIGs) Solar Panels - This Thin Film Technology has the highest Solar Cell Efficiency and a number of established companies like TSMC,Q-Cells,Honda and startups like Miasole,Nanosolar,Solyndra are using this technology.However its production is not easy as four different materials are used.Miasole has been claiming to have achieved an efficiency of 13.8%.General range is between 11-14%.Note Solar Shingles being sold by Dow and Uni Solar also use this technology as its weight is much lower than normal silicon solar panels.CIGs Technology is also used in making flexible thin solar panels which can be used for camping,BIPV and other applications where weight is an issue.
Other types of solar panels which are in niche production are organic solar panels made by Dyesol,Copper Zinc Tin Sulfure Selenium (CZTS) Solar Panels being developed by Solar Frontier-IBM,Multijunction Solar Cell Panels developed by Emcore,Boeing and others.
Different Power Ratings of Solar Panels
Solar Panels are available in such a wide variety of power ratings that it can confuse a layman on what size of solar panel to buy for his home use.For small uses like charging a iPod or a laptop a small 5-20 Watt solar panel will do.However if you want to use solar energy to power your house you would need higher power solar panels with ratings of 150-250 watts.If you have a smaller rooftop area then you would need to invest in higher rating and higher efficiency monocrystalline solar panels.There are also solar panels which come in different colors like Black Solar Panels from Sunpower.You also have to take into account the weight that your roof can take.If it can take only a small weight then you may need to buy amorphous silicon or CIGs solar panels which have high efficiency to weight ratios.
The most commonly used solar panels come under 5 watts,20 Watts ,50 watts,100 watts,150 watts,200 watts,240 watts.
You can read more about Solar Array Design.