Solar film panels. Technologies that make solar panel thin & flexible

olar technologies do not stand still, making solar energy increasingly efficient and affordable. Thin film (TF) panels are one of the most promising lines of solar research. In fact, they are often considered the future of the solar industry. They cost less, use no toxic materials, generate less waste, and are much easier to produce. In addition to this, thin solar panels require less semiconductor material in the production process than conventional crystalline panels.

What are solar film panels?

Like their crystalline counterparts, solar film panels convert sunlight into electrical power using the photovoltaic effect. But unlike traditional PV modules, they are light, thin, and flexible.

What makes this next-gen solar panel thin?

The technology that allows making a PV solar panel thin is called chemical vapor deposition. It implies putting several fine layers of semiconductor material on top of each other and placing them on glass, stainless steel, or plastic substrate. The plastic foundation makes the panel the most bendable so that it can be adjusted to almost any roof’s shape. With glass or metal substrates, solar film panels are stiffer and heavier.

Each PV layer is only 1 micrometer (µm) thick, which is 20 times less than silicon solar wafers. This allows making a TF solar panel thin, lightweight and flexible.

Types of flexible PV modules

Several types of materials are used for PV layers in thin film solar manufacturing. Let’s take a look at each of them.

Amorphous silicon (a-Si) solar panels

Amorphous PV panels are the oldest thin film solar technology. The simplicity of amorphous solar cells earlier made them a popular technological solution for electronic devices with low power consumption such as wrist watches and hand-held calculators.

Amorphous thin film solar modules are manufactured from silicon just like traditional PV panels, but their cells represent a non-crystalline layer deposited on a substrate. Amorphous silicon (a-Si) has a significant light absorption capacity, which makes it an excellent choice for manufacturing solar panels of minimum thicknesses.

Amorphous solar panels offer a wide range of benefits. Firstly, their manufacturing process doesn’t require toxic components, while such components are sometimes used to fabricate other types of PV panels. Secondly, they require less silicon, which makes them cheaper. Additionally, they are highly flexible and almost immune to cracks.

As for shortcomings, low efficiency is the biggest one. While the efficiency rate of standard crystalline solar panels can reach up to 20%, amorphous panels are only about 7% efficient. And most likely they won’t be able to compete with conventional PV modules in the future: their maximum theoretical efficiency stands at 15%.

Cadmium telluride (CdTe) solar panels

Cadmium telluride PV modules are the second most popular solar option after crystalline silicon, representing approximately 5% of the solar panel market. In CdTe solar cells, the lower electrode is made from copper-doped carbon paste and the upper one is made from tin oxide or cadmium-based stannous oxide with cadmium sulfide placed between them.

The average efficiency of CdTe modules is around 18%, although the most advanced versions reach an efficiency rate of 22%. Cadmium telluride panels are cheaper than solar film panels and have the shortest payback period of all thin modules on the market.

The main problem with CdTe panels is the use of potentially hazardous materials in their production since cadmium and cadmium telluride have toxic properties. They do not pose a threat to humans or the environment as they operate, but the disposal of old CdTe panels remains a cause for public concern. In addition to this, telluride is a relatively rare element that is not easy to find, which can be an additional challenge for large-scale manufacturing.

Copper indium gallium diselenide (CIGS) solar panel

CIGS solar panel thin film technology is relatively new, but it has the potential to significantly reduce the cost of solar panel production. It uses a compound semiconductor material that includes copper, indium, gallium, and selenium, which helps achieve an energy efficiency of 22.6% which is not only the highest of all thin film cells but is even higher than of polycrystalline silicon cells.

The main disadvantage is pollution, as CIGS like cadmium telluride panels use the toxic chemical cadmium. However, in CIGS panels the percentage of cadmium is lower than in CdTe alternatives, and therefore they are considered a more environmentally-friendly option. Besides, some models use zinc instead of cadmium, which minimizes the environmental harm. Another drawback is price, as CIGS modules are expensive to manufacture.

Organic photovoltaic (OPV) solar panels

The final type is organic solar cells - the third generation of photovoltaic technology. Unlike inorganic PV cells, an OPV cell uses organic absorbers, usually polymers or small organic molecules.

The abundance of the used material is a major advantage that makes organic PV solar panels cheaper to produce. Another benefit is aesthetics, as the possibility of using different types of organic absorbers opens doors to producing thin film solar modules of various colors.

However, the efficiency of OPV modules reaches only 11%, which limits their ability to be used in large-scale projects. Additionally, OPV panels struggle with a much shorter lifespan than other thin film options.

Conventional vs TF solar power modules

Crystalline silicon PV modules are currently the most widely used because they deliver stable performance and are backed by established technologies. Although some solar panel thin film technologies outperform crystalline counterparts, thin film solar efficiency is generally two times lower. This implies that crystalline cells are also more space efficient, as you will need less rooftop space for the same capacity. One more advantage is a longer lifespan. While thin film cells’ lifetime is about 10-20 years, the average life of crystalline silicon PV modules is 25 years. Standard silicon panels are also much more damage-resistant due to the tempered glass protection. And finally, the costs of crystalline modules go down steadily narrowing the gap between crystalline PV and solar film panels.

The first and the most obvious advantage of solar panel thin modules is affordability, as thin panel production uses much less silicon. The efficiency of all solar panels falls on hot days, but thin options are way more heat-resistant.

Solar film panels are shadow tolerant and work better on cloudier days, generating some amount of power even when the sun isn’t shining. The flexibility of thin panels makes it possible to adjust them to your roof more easily than crystalline. And last but not least, solar panel thin film options are the best choice for low-angle installations.

To sum it up, solar film panels can be the best solution for homeowners with non-standard rooftops or budgetary limitations.