These Ultra-Light Solar Cells Can Turn Almost Any Surface into a Photovoltaic Source


Solar energy, a renewable form of energy, can be converted into thermal energy and electrical energy. Advanced solar technologies can strap the energy for a variety of uses, including generating electricity, providing light or a comfortable interior environment, and heating water for domestic, commercial, or industrial use. The large magnitude of solar energy available makes it a highly appealing source of electricity. In 2020, solar energy was the cheapest source of electricity. Solar energy technology doesn’t end with electricity generation by PV or CSP systems. The advanced technologies also made the whole world depend on the source as the world is trying to maintain the climate changes.

Researchers at the Massachusetts Institute of Technology (MIT) have developed ultra-thin, ultra-light solar cells that can turn almost any surface into a photovoltaic source. Flexible solar cells are much thinner than human hair and adhere to a lightweight fabric, making them easy to install on any solid surface, making them easy to install on any solid surface. It can provide energy on the go as a portable energy fabric or can be rapidly transported and deployed to remote areas to assist in emergencies. It weighs 100 times less than conventional solar panels, produces 18 times more power per kilogram, and is made with semiconductor inks with a printing process that can be scaled up to large-scale manufacturing in the future.

Solar Cell Technology
Given their extremely thin and light nature, solar cells can be laminated to various surfaces. For example, it can be incorporated into the sails of boats to provide power at sea, attached to tents and tarpaulins used in disaster relief efforts, or attached to the wings of drones to extend their flight range. This lightweight solar technology can be easily integrated into the built environment with minimal installation effort.

The metrics used to evaluate a new solar cell technology are typically limited to their power conversion efficiency and their cost in dollars-per-watt. Just as important is inerrability, the ease with which the new technology can be adapted. The lightweight solar fabrics enable inerrability, providing impetus for the current work. Researchers tried hard to accelerate solar adoption, given the present urgent need to deploy new carbon-free sources of energy.

Slimmed Down Solar
Traditional silicon solar cells are fragile and must be encased in glass and packaged in heavy, thick aluminum frames, limiting where and how they can be placed. Six years ago, a team at ONE Lab produced solar cells using a new class of thin-film materials that are light enough to ride on a soap bubble. However, these ultra-thin solar cells are manufactured using complex vacuum-based processes, which can be expensive and difficult to scale. We set out to develop fully printable thin-film solar cells using sophisticated manufacturing techniques. To manufacture solar cells, they use nanomaterials in the form of printable electronic inks. In the MIT.nano clean room, a slot die coater is used to coat the solar cell structure. It applies a layer of electronic material to a prepared removable substrate that is only 3 microns thick. Using screen printing (a technique similar to printing a design on a T-shirt), electrodes are attached to the structure to complete the solar panel.

Researchers can then peel printed modules about 15 microns thick from the plastic substrate to create ultra-lightweight solar devices. However, such thin and self-supporting solar panels are difficult to handle and break easily, making them difficult to deploy. To solve this challenge, the MIT team searched for a lightweight, flexible, high-strength substrate to which solar cells could be glued. They identified woven fabric as the best solution as it provides mechanical strength and flexibility with little added weight.

Encapsulating these solar cells with heavy glass, as is done with conventional silicon solar cells, would minimize the value of current advances, so the team is currently working on the current ultra-thin solar cells.

They found the ideal material. It's a composite fabric known as Dyneema that weighs just 13 grams per square meter. This fabric is made of very strong fibers and was used as a rope to lift the sunken Costa Concordia cruise ship from the bottom of the Mediterranean Sea. Solar panels are glued to this sheet of fabric by adding a layer of UV-curable adhesive just a few microns thick. This creates an ultra-lightweight and mechanically robust solar structure. While it may seem simpler to print solar cells directly onto the fabric, this allows the choice of a possible fabric or other receptive surfaces to be combined with all the processing steps and chemical and thermal processes required to manufacture the device. Researchers are trying to separate solar cell manufacturing from final integration.

Outshining Conventional Solar Cells
Researchers have tested it and found that it can generate 730 watts per kilogram free-standing and about 370 watts per kilogram when placed on high-strength Dyneema fabric. That's about 18 times more power per kilogram than traditional solar array cells. A typical rooftop solar array in Massachusetts is around 8,000 watts. To generate the same amount of electricity, our fabric solar power will only add about 20 kilograms (44 pounds) to the roof.

They also tested the durability of the device and found that even after they rolled and unrolled the fabric solar panel more than 500 times, the cell retained more than 90 percent of its initial power-generating capacity. Those solar cells are much lighter and more flexible than conventional cells, but they must be wrapped in another material to protect them from the environment. The carbon-based organic materials used in cell fabrication can be modified by interacting with moisture and oxygen in the air, which can affect cell performance.

Encapsulating these solar cells with heavy glass, as is done with conventional silicon solar cells, would minimize the value of current advances, so the team is currently working on the current ultra-thin solar cells. Researchers are developing an ultra-thin packaging solution that adds only a small amount of weight to the optical device.

Researchers are working to remove as much non-solar active material as possible while maintaining the form factor and performance of these ultralight and flexible solar structures. For example, scientists know that printing removable substrates can further streamline the manufacturing process. This is the same process used to make the other layers of the device. This will accelerate the introduction of this technology into the market.

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