Thin-film solar cells are a rapidly growing category of solar photovoltaic cells that directly convert solar energy into electricity usable within the home. Thin-film cells consist of one or more layers of photovoltaic material on a substrate. Solar cells under the thin-film category are defined by the type of material used in cell construction.
Thin-film solar cells are commonly equated with the second “generation” of solar cell, the first being conventional crystalline silicon-based solar cells. The appeal of thin-film technology lies in inexpensive production, resulting from the need for less material, most notably expensive silicon, in panel production (e.g. no bulky aluminum frame).
Building Integrated Photovoltaics
Because of their slim size, thin-film solar cells have become the leader in Building Integrated Photovoltaics (BIPV). They can be easily incorporated into a building’s design, typically as part of the roof structure in the form of solar shingles or rolls for metal roofing.
Types of thin-film solar cells include:
- Amorphous silicon (aSi)
- Cadmium Telluride (CdTe)
- Copper indium gallium selenide (CIGS)
- Dye-sensitized solar cells (DSC or DSSC)
- Organic solar cells
As mentioned earlier, different thin-film solar cells are identified by the material used in their production, although developers use names interchangeably. For instance, dye-sensitized solar cells are commonly referred to as organic solar cells because the “dye” used is often made from organic material. And DSCs are often grouped with third-generation solar cells because they don’t necessarily use a semiconductor material, but nevertheless are applied in thin films. There is still no clearly defined separation between many different types of solar cell.
Breakthroughs and Barriers
Again, the main advantage of thin-film cells is low production costs, a factor that drives up the cost of today’s most efficient (crystalline silicon) solar cells and is a primary reason that the solar industry is so reliant on government incentives for widespread distribution.
But the ideal, affordable solar cell must do one better than cheap production. It must have a high rate of efficiency in converting sunlight to electricity. So far, thin-film cells have been lacking in that department. World leader in thin-film production, Arizona-based First Solar has dominated the thin-film industry thus far with a solar panel that is just under 11% efficient. While conventional solar panels maintain efficiencies at 15-20%, the low production cost of First Solar modules has facilitated their rise into prominence. Thin-film solar modules in general are expected to take over market share of solar panels within the next few years.
Recently, another thin-film manufacturer, Nanosolar, has begun mass production of its thin-film module that edges out First Solar’s efficiency rating. Nanosolar’s panels are made using nanotechnology to create a “solar ink” using CIGS solar cells. This allows for a printing press-like manufacturing process that the company claims will produce solar modules three times faster than First Solar.