Friday, 30 August 2013

Poly Crystalline VS Mono Crystalline Modules

The difference starts during the process of creation.  Monocrystalline silicon is created by slowly pulling a monocrystalline silicon seed crystal out of melted monocrystalline silicon using the Czochralski method to form an ingot of silicon.  A seed crystal is a small piece of silicon which is used as a foundation for the molten molecules.  By having a foundation, the molten molecules are able to connect together faster to form an ingot.  While the seed crystal is being withdrawn, it is rotated slowly and temperature is lowered slowly.  This helps form the cylindrical shape until it has the right diameter which is when temperature remains constant. 

The monocrystalline form is used in the semiconductor device fabrication since grain boundaries would bring discontinuities and favor imperfections in the microstructure of silicon, such as impurities and crystallographic defects, which can have significant effects on the local electronic properties of the material. On the scale that devices operate on, these imperfections would have a significant impact on the functionality and reliability of the devices. Without the crystalline perfection, it would be virtually impossible to build Very Large-Scale Integration (VLSI) devices (figure at right), in which millions (up to billions, circa 2005) of transistor-based circuits, all of which must reliably be working, are combined into a single chip to get e.g. a microprocessor. Therefore, electronic industry has invested heavily in facilities to produce large single crystals of silicon.

Monocrystalline silicon is also used in the manufacturing of high performance solar cells. Since, however, solar cells are less demanding than microelectronics for as concerns structural imperfections, monocrystaline solar grade (Sog-Si) is often used, single crystal is also often replaced by the cheaper polycrystalline or multicrystalline silicon. Monocrystalline solar cells can achieve 17% efficiency whereas other types of less expensive cells including thin film and polycrystalline are only capable of achieving around 10% efficiency.

Few solar charger companies use monocrystalline solar panels because of the higher cost to produce the solar cells, although these higher efficiency products are starting to pop up as consumers demand more efficient products. The 2010 Consumer Electronics Show showcased one of these high-efficiency monocrystalline chargers known as the JOOS Orange and awarded it the 2010 Best of Innovations Award.

Polycrystalline silicon is made through a simpler method.  Instead of going through the slow and more expensive process of creating a single crystal, molten silicon is just put into a cast and cooled with a seed crystal.  By using the casting method, the crystal surrounding the seed isn’t uniform and branches into many, smaller crystals, thus "polycrystalline". 

Currently, polysilicon is commonly used for the conducting gate materials in semiconductor devices such as MOSFETs; however, it has potential for large-scale photovoltaic devices. The abundance, stability, and low toxicity of silicon, combined with the low cost of polysilicon relative to single crystals makes this variety of material attractive for photovoltaic production. Grain size has been shown to have an effect on the efficiency of polycrystalline solar cells. Solar cell efficiency increases with grain size. This effect is due to reduced recombination in the solar cell. Recombination, which is a limiting factor for current in a solar cell, occurs more prevalently at grain boundaries.

The resistivity, mobility, and free-carrier concentration in monocrystalline silicon vary with doping concentration of the single crystal silicon. Whereas the doping of polycrystalline silicon does have an effect on the resistivity, mobility, and free-carrier concentration, these properties strongly depend on the polycrystalline grain size, which is a physical parameter that the material scientist can manipulate. Through the methods of crystallization to form polycrystalline silicon, an engineer can control the size of the polycrystalline grains which will vary the physical properties of the material.

Here are the bullet point differences between the two methods:
  • Price
Monocrystalline solar cells cost more than polycrystalline for the same size.
  • Efficiency
Monocrystalline cells have a higher efficiency than polycrystalline cells due to the structure being made from one large crystal as opposed to many small ones.  In addition to having an overall better efficiency, monocrystalline panels can perform up to 10% better than polycrystalline panels in high ambient temperatures.
  • Size
Since monocrystalline panels are more efficient per area, the size of the solar panel kits is less than a polycrystalline solar panel for the same wattage.  If you are limited on size and want to get the most energy possible, monocrystalline panels are the better choice. That is the main reason Monocrystalline solar kits are more popular.
  • Looks
In terms of looks, monocrystalline panels have a nice uniform color and have a more circular cell shape.  Polycrystalline cells are in squares and have inconsistencies in the color sort of like granite. 
  • Longevity
Even though a monocrystalline panel has the potential to last up to 50 years, most warranties only go up to 25 years which polycrystalline panels are able to reach just fine.
Overall, the production process for monocrystalline silicon is mature, and the process for polycrystalline in still maturing. As purity and process tolerances for polycrystalline Si improves, the performance gaps between the two are narrowing.
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Peak Solar is a company that is trying to turn the world a little bit green. We offer Solar Kits for home that will help you to get some income and get you to do something on your part for the earth.


Tuesday, 13 August 2013

Mono-Crystalline Modules

Monocrystalline photovoltaic electric solar energy panels have been the go-to choice for many years. They are among the oldest, most efficient and most dependable ways to produce electricity from the sun.

Each module is made from a single silicon crystal, and is more efficient, though more expensive, than the newer and cheaper polycrystalline and thin-film PV panel technologies.  You can typically recognize them by their color which is typically black or iridescent blue.

Benefits of Monocrystalline Solar Panels provided by Renewable Warehouse:

1. Longevity

Monocrystalline solar panels are first generation solar technology and have been around a long time, providing evidence of their durability and longevity. The technology, installation, performance issues are all understood. Several of the early modules installed in the 1970's are still producing electricity today. Single crystal panels have even withstood the rigors of space travel!

2. Efficiency

As already mentioned, PV panels made from monocrystalline solar cells are able to convert the highest amount of solar energy into electricity of any type of flat solar panel. Consequently, if your goal is to produce the most electricity from a specific area (e.g., on a roof) this type of panel should certainly be considered.

3. Lower Installation Costs

The cost of solar panels is typically around 60% of the cost of a fully installed solar power system, with installation being a significant cost component. Although I haven't confirmed this yet, one installer in Australia (who sells and installs several types of solar panels) has said that some amorphous thin film panels actually need more mounting rails and take longer to install; adding to the overall cost of the system.

4. Embodied Energy

While thin-film solar panels offer a lower level of embedded energy per panel, the fact that more panels are needed somewhat negates this aspect, especially given the extra mounting rails sometimes needed.

5. Other Environmental Concerns

Some thin film solar products uses cadmium telluride. Cadmium is a heavy metal that accumulates in plant and animal tissues. Cadmium is a 'probable carcinogen' in humans and animals.

6. Greater Heat Resistance

Like other types of solar panels, monocrystalline solar modules suffer a reduction in output once the temperature from the sunlight reaches around fifty degrees Celsius/a hundred and fifteen degrees Fahrenheit.

7. More Electricity

Besides producing more electricity per sqm of installed panels, thereby improving your cash flow (from either a reduction in your electrical bill or from the sale of the electricity or in some areas both), for those who are "going green" and are concerned about the environmental impact of solar panels, monocrystalline panels reduce the amount of electricity needed from local power plants,

8. Bankability

A corollary of the durability and longevity of this type of solar panels is that in areas where there is an established track record of performance, we are able to obtain bank financing of up to 90% for our projects, which is certainly a big reason why Germany has the largest installed base of solar panels in the world.

Currently, Peak Solar manufacturers the most efficient photovoltaic systems (monocrystalline solar panels )- with an efficiency of 22.5 percent. In future they will break the world's record for commercially produced solar cells at 24.2% for sure.

Monday, 5 August 2013

Cost Of Grid Tied/ Off Grid Solar Installations

 Grid-tied solar Kits are connected to the utility company’s power lines. If the home or business needs more electricity than it can produce it draws energy from the grid and if it is producing excess electricity, it injects it into the electrical grid. Electricity added to the grid is credited to the homeowner or business’ electricity bill. When power is drawn from the grid, this electricity credit is reduced. This process is called “net-metering” and is accomplished with a bi-directional or smart meter.
There are also grid-tied installations that reserve power in a battery backup that is used during power outages. The solar panels charge the batteries so that continuous power is available, even if the utility grid is down. When the outage is fixed, net-metering resumes.

Off-grid systems are usually implemented in locations that are too remote to receive service from a utility. These systems can generate AC power that can run regular appliances and electric devices. They store power in batteries that are used to supply power when sunlight is not available. Those that generate DC power are used to power remote telecommunications gear, appliances used in boats and recreational vehicles as well as farm equipment. DC is less expensive than AC because it does not require an inverter. AC systems can power common home appliances.

Source: Peak Solar