WHAT IS THE DIFFERENCE?

Monocrystalline vs Polycrystalline Photovoltaic Cells

You may have heard the terms monocrystalline and polycrystalline used to describe photovoltaic cells, but what does that mean and how does it affect a cell’s performance?

Basic Anatomy of a PV cell

A lump of pure silicon

The main ingredient in most photovoltaic cells is silicon – the same element that makes computer chips possible.  Silicon is the second most abundant element in the Earth’s crust, but unfortunately it is normally found in the form of silica – you might know it as sand.

Various methods exist to extract the pure silicon, but the most common is carbothermic reduction, where the silica is heated to 1700°C in the presence of carbon.  As the silicon cools it forms crystals.

The speed at which the silicon cools is one of the critical factors that determine the crystal size: the slower the silicon cools, the larger the crystals.  With care the silicon can be extracted as one large crystal.  As you might imagine, that’s more difficult, which means it’s more expensive.

The difference between monocrystalline vs polycrystalline solar cells is simply that one is produced from a single crystal of silicon and the other is produced from a piece of silicon consisting of many crystals.

Practical Differences

So what is the impact on cell performance?

Since polycrystalline cells contain many crystals, they have a less perfect surface than monocrystalline cells.  This means that they absorb slightly less solar energy and produce slightly less electricity per square foot. On the plus side, the process of creating the silicon for a polycrystalline cell is much simpler, so these cells are generally cheaper per square foot.

On balance, the cost of monocrystalline vs polycrystalline based panels per Watt of power output works out about the same, but the polycrystalline panels will be slightly larger than equivalent monocrystalline panels.  This is generally not a problem unless you have a very limited area available for the installation, in which case you will want to maximise the power output per square foot.

Monocrystalline and polycrystalline can also look different.  Monocrystalline cells will usually have a perfectly uniform appearance, but polycrystalline cells will appear “grainy” – think of how a granite worktop looks and you’ll get the idea.  From a distance this will not be noticeable, so if they are going on your roof this is unlikely to worry you.

 So which should I choose?

At the end of the day, unless you are very space constrained, your choice of panel will probably be dictated by factors other than whether they are made up of mono or polycrystalline cells.

The price per Watt is an important factor, and that is largely unaffected by the choice of monocrystalline versus polycrystalline cells.  In some circumstances, the area available for the installation may be a factor that pushes you to go for monocrystalline cells.

But the most important thing is to make sure that you choose a reputable installer and manufacturer.  Your panels will most likely give you many years of trouble free operation, but for your own peace of mind you will probably want to choose a manufacturer that is likely to be around for long enough to honor the terms of the guarantee – which may be up to 25 years!

Please contact Electrical Systems and Services, Inc should you have any questions or would like to schedule a site survey to see the potential your home or business could have with a solar system installed.

MAYBE IT'S TIME FOR YOU TO THINK SOLAR?

U.S. SOLAR MODULE DEMAND EXPECTED TO DOUBLE IN 2012

The U.S. market for solar panels is likely to double in 2012, thanks to government policies and falling prices, although new tariffs on panels imported from China could contribute to slower growth in 2013, according to a new study.

U.S. developers are likely to install 3,300 megawatts of solar panels this year, nearly double the amount installed in 2011. More than 500 megawatts of solar power were installed in New Jersey, California, Arizona, Massachusetts and other states in the first quarter 2012 alone, in what is usually a slow time for solar installations due to winter weather.

The global solar power market has been turbulent for manufacturers, as prices have plunged amid an over supply of panels. But the falling prices, as well as faster development for large scaled solar powered plants, have driven strong demand for solar equipment.

Government subsidies, such as the federal rebate of 30% of the cost of each solar system, and state and local incentives have been driving growing demand for solar. The lowering prices have also played a role in the increase of interest for solar projects.

Average solar module prices fell by one- half in 2011, to about 94 cents a watt. That followed a 2010 drop of 27% in prices. The lower panel prices, combined with lower prices for other components, led to a drop in total solar systems installation costs. This was true in both large scale utility solar systems, as well as residential roof top installations.

Electrical Systems and Services, Inc is proud to be a NABCEP certified installer and part of this growing market. Now is the time to contact Electrical Systems to have a Free, No obligation assessment to your business or residence to see if this is the right time for you to go Solar.  Please contact us, so we can get yours scheduled.

PRICE REDUCTION FOR ELECTRIC CARS COMING?

US battery maker claims electric car breakthrough

     United States manufacturer said it has developed a new automotive battery which can perform in extreme temperatures, offering the potential to cut the cost of making electric cars.

The Nanophosphate EXT would reduce or eliminate the need for heating or cooling systems, which is expected to create sizeable new opportunities for automotive and other types of batteries.

Nanophosphate EXT is a game-changing breakthrough that overcomes one of the key limitations of lead acid, standard lithiumion and other advanced batteries.

The new battery technology can reduce or even eliminate the need for costly thermal management systems, which  will dramatically enhance the business case for deploying  lithiumion battery solutions for a significant number of applications.

Testing showed the battery can retain more than 90 percent of its initial capacity at 113 degree Fahrenheit. It also can deliver starting power at minus 22 degree below Fahrenheit.

This comes amid sputtering sales in the United States of electric cars, and doubts about whether the high purchase costs will be justified by lower operating costs.

The technology could help cut costs of "thermal conditioning."

Most electric cars have some system of pumping coolant to remove excess heat from their battery packs.

Pumping coolant through this system eats up energy and reduces on-road range.

This new technology would reduce the weight, complexity, and cost of future plug-in vehicles, bringing down their cost and moving them closer to mass-market competitiveness.