Thin Film Photovoltaic

The Thin Film PV Story

Thin Film Photovoltaic technology has changed the horizon for solar. The second generation of photovoltaics creates a truly portable solar panel. Roll or fold panels for easy transport.

Roll it up or Spray it on. Is thin film the answer we've all been waiting for?

So what is thin film photovoltaic technology?

Also referred to as 2nd generation photovoltaics, thin film pv is a relative newcomer to the solar family.

To reflect recent progress in photovoltaic development, the industry has been categorized into, 1st, 2nd and 3rd generation pv. These three categories reflect certain milestones and the order in which each concept has become generally accepted.

Thin film pv is the 2nd generation, meaning it's the generation that comes after the silicon solar panel. A new and cheaper but, alas, less efficient type of solar collector that has literally broadened the horizon for solar by collecting spectrums of light that are not visible to the eye and exist even after dark!

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1st Generation Photovoltaics

1st generation pv represents over 90% of today's solar infrastructure (silicon panels). Of course, 1st generation technology has been around for much longer than thin film photovoltaic technology and has gained a significant foothold in the market in that time.

In spite of years of research silicon panels are still relatively expensive to produce and no matter how much cheaper they become they have another limitation. Theorists agree that the amount of sunlight that falls on a silicon solar panel that can be successfully converted into electricity is 26% - 29%. They don't all agree on the the exact percentage but they do agree that the efficiency of a silicon solar panel is limited.

1st generation pv can be enhanced, however, by concentrating the solar rays with mirrors, scientists have made great success at increasing efficiency levels. Silicon's proven track record in an emerging industry has provided a certain momentum and it is unlikely that it will be overtaken any time soon by 2nd or 3rd generation advances.

2nd Generation Photovoltaics - Thin Film Photovoltaic

Second generation technologies have substantially reduced the cost of producing a solar cell. Referred to as "thin film" because a thin film of CIGS (copper indium gallium selenium) is applied to a substance such as foil or glass. Other thin film technologies exist but tend to break down after periods of sun exposure. At the moment CIGS appears to be the most stable when exposed to sunlight.

A thin film semi conductor is 100 times thinner than silicon semi conductors and can be applied to thin sheets making for a solar panel not much thicker than a sheet of good quality paper. That translates into lightweight, portable and compact panels.

Here's a look at Nanosolar's Thin Film Photovoltaic Processor.

There's promise that the same nanosolar collectors can be suspended in paints to become spray on solar paints or mixed into concrete products, even woven into fabrics. The possibilities, then, become limitless.

Thin film photovoltaic companies are gaining an increasingly strong foothold in the solar marketplace assisted somewhat by polysilicon shortages between 2006 and 2008 which created an inability for silicon companies to grow during a time of high demand.

Will it take over the market? Unlikely, at least for the time being, but it will continue to grow alongside silicon solar technologies and will be better suited for some applications than silicon solar. Likely the two will maintain strong positions until 3rd generation progress ushers in the holy grail (inexpensive, environmentally benign and efficient) solar collector.

Advantages of Thin Film Photovoltaic Technology

Inexpensive to produce.
Thin film pv can be produced much faster than silicon.
Harvests infrared light spectrum.
Super thin materials can be rolled or folded into compact and portable solar panels.
Versatile - Can be incorporated into building materials, paints, fabrics.

Disadvantages of Thin Film Photovoltaic Technology

Less efficient than silicon cells. Efficiency levels hover around the 20% mark.
The CIGS (copper indium gallium selenium) process uses rare metals that are already in short supply. Indium, gallium and even copper prices are almost sure to rise sharply as world supplies dwindle and demand increases. Global reserves of these metals is questionable but some reports believe that indium will be gone by 2017. More disadvantages of solar energy

3rd Generation

3rd time lucky? Utilizing thin film photovoltaic techniques, 3rd generation photovoltaic research intends to take solar to the ultimate level. Honing efficiency levels by marrying the benefits of thin film techniques with concentrators, mirrrors and other boosting methods while at the same time, addressing environmental issues, 3rd generation photovoltaics will be a giant step toward a solar future for everyone.

Three issues that have plagued the solar industry are:

Cost to produce solar cells. Thin film photovoltaic research and development have done a great deal to address this issue. Production costs are minimal compared to silicon solar panels.
Efficiency, or how efficient a solar cell is at converting the sunlight that strikes it, into electricity. Efficiency rates have reached percentages as high as 22% meaning that (some) solar cells can convert 22% of the sun's rays that strike them into electricity. Some claim efficiency levels even higher than that and adding mirrors or concentrators can boost that.

It is unlikely, even if an efficiency of 33% is achieved, that 1st generation solar will ever reach a point where it costs less than $1 per Watt. According to theoretical laws of physics 26% to 29% efficiency is as high as we can expect to reach with 1st generation technologies. Although thin film is cheaper to produce it's not as efficient as 1st generation silicon solar converting at rates around 20%
Environmental issues. Although solar is a "clean energy" to use - once the panels are produced - the making of the solar panel (whether 1st or 2nd generation) brings up some pretty serious environmental considerations. The amount of energy required to fabricate a silicon solar panel represents about 20% of the energy that panel can be expected to produce in it's lifetime. Granted, that's a whole lot better than the 100% required to produce early models. (Kinda defeats the purpose). Still, large amounts of energy are required to produce a solar panel. Additionally silicon solar panels contain cadmium which is very harmful to the environment and thin film technologies use rare metals some of which may soon be gone. Obviously these are issues that must be addressedto avoid trading one environmental blunder for another. More about the disadvantages of solar energy