Micrometric Photovoltaic Cells a ‘Technological Breakthrough’ for Device Miniaturization

In an age where sustainable energy solutions are as crucial than ever, the evolution of photovoltaic (solar) technology stands at the forefront of innovation.  A recent example of this comes from the University of Ottawa (U of O), where a team of scientists has successfully “achieved a world first by manufacturing the first back-contact micrometric photovoltaic cells.”  This is being described as a “crucial step” in facilitating the continued miniaturization of electronics.

The team responsible for this breakthrough was spearheaded by,

• Mathieu de Lafontaine, a postdoctoral researcher at U of O and part-time physics professor
• Karin Hinzer, vice-dean, research, and University Research Chair in Photonic Devices for Energy at the Faculty of Engineering

While the U of O was central to this breakthrough, the team was also supported by Université de Sherbrooke in Quebec and the Laboratoire des Technologies de la Microélectronique in Grenoble, France.

What Are Photovoltaic Cells?

Photovoltaic cells, commonly known as solar cells, are devices that convert sunlight directly into electricity.  They operate on the principle of the photovoltaic effect, where light energy (photons) striking semiconducting materials such as silicon induces an electrical current.  This process occurs as the photons dislodge electrons from their atomic orbits, creating a flow of electric charge.

These cells are the fundamental building blocks of solar panels and are critical in harnessing solar energy, a renewable and clean source of power.  The recent advancement by the U of O in developing micrometric photovoltaic cells marks a significant leap in this technology, offering more efficient and compact solutions.

What are ‘Back-Contact Micrometric Photovoltaic Cells'?

As mentioned, Back-contact micrometric photovoltaic cells represent a groundbreaking advancement in solar technology.  Unlike traditional solar cells, where the electrical contacts are located on the front and back surfaces, back-contact cells have all their electrical contacts on the rear side.

This unique design significantly reduces the shadowing effect caused by electrodes on the cell's surface, thereby enhancing the cell's ability to capture sunlight.

What is the ‘Shadowing' Effect?

The ‘shadowing' effect in solar cells refers to the obstruction of sunlight caused by the presence of electrical contacts on the surface of the cell.  Traditional photovoltaic cells have metallic contacts (usually made of silver or aluminum) on the top surface that collect and transport the electrical current generated by the cell.

These contacts, however, can block a portion of the incoming sunlight, preventing it from reaching the photovoltaic material underneath.  This blockage reduces the amount of light available for conversion into electricity, thereby decreasing the overall efficiency of the solar cell.

Source: www.sciencedirect.com/science/article/pii/S2666386423005325

Reducing this shadowing effect is crucial for several reasons:

1. Increased Efficiency: By minimizing the area covered by contacts, more of the cell's surface can actively participate in light absorption and conversion to electricity.  This enhances the overall efficiency of the cell, allowing it to generate more power from the same amount of sunlight.
2. Cost-Effectiveness: Higher efficiency means that the same amount of energy can be produced from fewer cells.  As a result, the overall cost of solar power systems can be reduced, making solar energy more competitive with other forms of energy, thereby increasing its accessibility to a wider range of users.
3. Versatility and Design Flexibility: Reducing shadowing allows for more innovative and flexible solar cell designs.  It can lead to the development of cells that are not only more efficient but also thinner and lighter, which can be particularly beneficial for applications subject to space and weight considerations, such as in aerospace, portable devices, and integrated building solutions.

Reducing the shadowing effect is key to advancing solar technology – which is now being addressed with these back-contact micrometric photovoltaic cells.  As a result, we can soon expect more efficient, cost-effective, and versatile solar cells that should ultimately contribute to the broader adoption of solar energy as a sustainable power source.

Why is Miniaturization Important?

Beyond reducing the shadowing effect in traditional photovoltaic cells, back-contact allows for greatly improved miniaturization.  This is crucial in the field of electronics and renewable energy technologies because it allows for more efficient use of space and resources while enhancing performance.

The miniaturization or ‘micrometric' aspect of these cells sees them come in about twice the thickness of a human hair.  As a result, these smaller, more efficient photovoltaic cells developed by the U of O can also significantly reduce production costs (purportedly as much as a threefold decrease).

“This technological breakthrough promises significant benefits for society. Less expensive, more powerful solar cells will help accelerate the energy shift.

Lightweight nuclear batteries will facilitate space exploration, and miniaturization of devices will contribute to the growth of the internet of things and lead to more powerful computers and smartphones” – Mathieu de Lafontaine

Interestingly, this miniaturization is not just about making devices smaller; it's about making them smarter and more adaptable to various environments.  In the context of an increasingly connected world, where the Internet of Things (IoT) and smart technologies are becoming ubiquitous, miniaturized photovoltaic cells can power an array of devices without the constraints of traditional power sources.

As such, this advancement can facilitate a greener, more sustainable approach to power generation and consumption, directly contributing to the shift towards a carbon-neutral economy.

Where Are They Used?

Photovoltaic cells have a wide range of applications that are constantly growing with advancements like back-contact manufacturing.  This versatility and appeal are largely due to their ability to generate electricity in a clean, renewable manner.

Beyond conventional power generation, they are integral in remote and portable power systems, like those used in space exploration, where they power satellites and spacecraft.

With the miniaturization of these cells, their applications extend to denser electronic devices, potentially transforming industries such as telecommunications and the Internet of Things (IoT).  As previously mentioned, miniaturization can lead to more efficient, compact, and versatile solar-powered solutions, broadening the scope of where photovoltaic technology can be applied.

Industry Players

As it stands, there are a few noteworthy companies facilitating growth within the sustainable energy sector that maintain a focus on solar applications.  The following are a few of these, along with multiple noteworthy additions.

1.  NextEra Energy Resources

NextEra Energy Resources, a subsidiary of NextEra Energy, is making significant strides in the solar energy sector.  In the first quarter of 2023, the company added about 2,020 MW of renewables and storage assets to its backlog, which included approximately 1.3 GW of solar, along with storage and wind assets.  This addition brought its project backlog to over 20.4 GW, showcasing a strong commitment to expanding its renewable energy portfolio​​​.

A notable project is the Sebree Solar 400-MW solar project in Henderson County, Kentucky, which is being developed by Sebree Solar, a subsidiary of NextEra Energy Resources.

Additionally, NextEra Energy Resources is also involved in another 200-MW solar project through Green River Solar, another of its subsidiaries.  These initiatives reflect NextEra Energy Resources' commitment to advancing solar energy as a key player in the renewable energy market.

2.  First Solar

First Solar, a prominent U.S.-based company specializing in cadmium telluride thin-film solar modules, has shown significant strides in solar initiatives as of 2023.  With $801 million in revenues and shipping 2.7 GW of solar module orders in a single quarter, the company is demonstrating strong growth and an emphasis on solar technology.  To meet the increasing demand, First Solar is expanding its manufacturing capacity both in the U.S. and internationally, aiming for a global capacity of 25 GW by 2026.

Notably, First Solar has pioneered the production of bifacial thin-film modules, a first in the industry.  This innovative technology allows for bifacial energy gain and higher energy yields, marking a significant advancement in solar module efficiency.

3.  SolarEdge Technologies

SolarEdge Technologies is widely viewed as a leader in smart energy technology.  This company made significant advancements in the solar energy sector in 2023, boasting record revenues of $943.9 million, with $908.5 million coming specifically from its solar segment.  This achievement is indicative of SolarEdge's robust presence in the solar industry.  In the first quarter of 2023 alone, SolarEdge shipped 3.6 Gigawatts (AC) of inverters and 221 MWh of batteries, underlining its substantial contribution to the solar energy market​

Notable Mentions

Final Thoughts

The advancements in photovoltaic cell technology, particularly through the development of back-contact micrometric cells, represent a potential quantum leap in solar energy.  This innovation not only enhances the efficiency and reduces the cost of solar power but also opens up new horizons for its application across various sectors.  The reduction of the shadowing effect and the focus on miniaturization are pivotal in propelling solar energy to the forefront of renewable energy sources.

As we embrace these technological strides, we edge closer to a future where widespread sustainable and clean energy is not just a possibility but a reality.