New materials and efficiency improvements are propelling solar technologies forward

There has been no shortage of technical improvements in the solar power sector, which has contributed to the industry’s resurgence after the coronavirus epidemic halted numerous projects. As nations established decarbonization objectives, more corporations set sustainability goals, and the desire for home improvements—an outgrowth of the pandemic—has helped residential rooftop solar.

Researchers have continued to create more efficient solar energy equipment, and the market has embraced innovation. A two-year extension of the 26 percent Investment Tax Credit (ITC) for solar power, enacted earlier this year by the United States Congress, has offered more encouragement for individuals and businesses interested in adopting solar.

And, rather than a better solar panel or inverter, a major driver in the expansion of solar power may be the deployment of energy storage to support solar development. “The most critical technical challenge for the solar sector right now is obtaining safe, dependable, and low-cost storage,” said Suvi Sharma, founder of Solaria, a solar technology and installation firm located in California. “In most regions of the nation, solar has become quite economically feasible.” It is ramping up and being deployed in almost every state. It competes with the grid. The one limitation of solar energy is that it cannot provide energy at all times of the day. To get the most out of solar, we must store the energy generated by solar systems, whether they are domestic, commercial, or utility-scale.”

Extending the ITC helped energy storage systems as well. These systems are also eligible for the tax credit if they receive at least 75% of their power from an onsite renewable energy system. And government officials are well aware of the need to reduce costs in order to support more solar deployment; earlier this year, the US Department of Energy (DOE) set a target of reducing the cost of solar energy by 60% within the next decade, as well as pledging millions of dollars to support new solar power technologies.


Efforts Made in Collaboration

Partnerships and partnerships are accelerating the rate at which technology advances in the solar business. In October, researchers at the National Renewable Energy Laboratory (NREL) and the Colorado School of Mines revealed the use of a novel approach to detect faults in silicon solar cells that affect efficiency. The insights learnt from their research, according to the organisations, “may lead to advances in the way manufacturers fortify their goods against what is known as light-induced deterioration [LID].”

According to the organisations, LID affects silicon solar cell efficiency by around 2%, resulting in a “substantial decline in power production throughout the 30- to 40-year lifespan of the technology deployed in the field.” More than 96 percent of the present worldwide market is made up of silicon solar cells. Because the most common semiconductor used to make these cells is boron-doped silicon, which is prone to LID, manufacturers have sought techniques to stabilize the solar modules. According to NREL experts, predicting the stability of such modules is difficult without a knowledge of the faults at the atomic level.

“Some of the modules have been entirely stabilized. “Some of them are just half-stabilized,” said Abigail Meyer, a Ph.D. student at Mines and NREL researcher. Meyer is the primary author of an article investigating the origins of the LID phenomena. Her co-authors include Mines and NREL researchers, including Paul Stradins, a principal scientist and project leader in silicon photovoltaic research at NREL. According to Stradins, the problem of LID has been investigated for decades, but the precise microscopic nature of what causes the deterioration has yet to be established. Through indirect experiments and theory, researchers have established that the issue lessens when less boron is utilized or when less oxygen is present in the silicon.

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The partnership between NREL and Mines used electron paramagnetic resonance (EPR) to discover faults responsible for the LID, with research financed by the DOE’s Solar Energy Technologies Office. As the sample solar cells decayed due to light, the microscopic analysis showed a specific fault signature. When the scientists used the same “regeneration” procedure to cure the LID that industry has embraced, the flaw signal vanished. The researchers also discovered a second, “wide” EPR signal that is altered by light exposure and involves far more dopant atoms than LID defects. They proposed that not all atomic changes caused by light result in the LID. The tools used to analyze LID, according to the researchers, may be expanded to identify other forms of degrading flaws in silicon solar cells, as well as in other semiconductor materials used in photovoltaics, such as cadmium telluride and perovskites.

Increasing Panel Efficiency

Solar cell and module designers are still looking for ways to improve photovoltaic (PV) panel efficiency. JinkoSolar and LONGi, two Chinese firms, have achieved solar conversion efficiencies of more than 25% using crystalline silicon technology. Australian researchers created a bifacial silicon solar cell with efficiencies of 24.3 percent on the front and 23.4 percent on the back, for a total effective output of roughly 29 percent. Oxford PV, situated in the United Kingdom, has reported a new efficiency record for its perovskite solar cells of 29.52 percent. Oxford PV finished building the manufacturing facility for its perovskite-on-silicon tandem solar cells in July and plans to commence full commercial production in 2022.

Solliance Solar Research, a Dutch consortium, announced in late October that researchers from three of its partners had achieved a 29.2 percent power conversion efficiency on a transparent bifacial perovskite solar cell combined with a crystalline silicon solar cell in a four-terminal tandem configuration. The cell is based on a highly near-infrared transparent perovskite cell developed by the Netherlands Organisation for Applied Scientific Research (TNO) and Belgian laboratory EnergyVille, as well as a 11.4 percent-efficient c-Si interdigitated back contact silicon heterojunction cell developed by Panasonic. EnergyVille has praised its work on tandem configurations, stating, “By putting two (or more) distinct solar cells with carefully selected material qualities on top of each other in so-called tandem arrangement, we may convert a greater part of the light spectrum into electrical energy.” In this technique, we are able to overcome the physical limits of single solar cells.” That is, by combining a perovskite top cell with a silicon bottom cell, EnergyVille hopes to achieve a tandem energy conversion efficiency of +30%, which is higher than the theoretical maximum of silicon solar cells, which is around 28 percent.

The vast bulk of the solar power business is dominated by crystalline silicon technology. However, in the United States, supply chain challenges and trade limitations on Chinese imports—including worries over polysilicon manufacturing in Xinjiang—have opened possibilities for thin-film makers. Arizona-based First Solar, which manufactures cadmium-telluride (CdTe) solar modules and panels, said this summer that it will invest about $700 million on a third U.S. manufacturing plant, increasing domestic production capacity by 3.3 GW. In addition, the business announced the development of a comparable 3.3-GW project in India.

China National Building Materials, a Chinese manufacturer of thin-film copper indium gallium diselenide panels, has announced an expansion of production, adding around 1 GW of capacity for CdTe modules.

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Solar Cells of the Future

“The most significant technological advance for solar panels and systems is the advent of n-type solar cells,” Sharma added. TOPCon (passivated contact) and heterojunction are the two most prevalent n-type solar cells, according to Sharma. A hetereojunction solar cell integrates two distinct technologies into a single device: a crystalline silicon cell sandwiched between two layers of amorphous thin-film silicon. When both technologies are utilized together, more energy may be gathered than if either method was employed alone.

“N-type solar cells are produced from wafers with a distinct chemical composition,” Sharma explained. “There will be a considerable change in cell production during the next three to five years.” What is now being generated is primarily p-type mono PERC cells [monocrystalline silicon cells]… they will all begin to migrate to n-type TOPCon and heterojunction cells.”

“Manufacturing of n-type cells is not tailored for a certain niche,” Sharma explained. These new cells will boost the efficiency of all solar panels and applications, not just one. By boosting the energy efficiency of all different types of PV panels, this breakthrough will have a huge influence on the whole industry and all solar deployments.”

Solaria’s new PowerXT 430R-PL (430 watt) solar panel will be available in March 2022. The panel will be designed for next-generation module level power electronics (MLPE), which are components that may be integrated into a solar PV system to increase its performance under certain situations, such as shadow. Microinverters and direct-current (DC) power optimizers are examples of MLPE devices that are meant to increase the energy production of a solar power system.


Following the Sun

New racking solutions are also improving the efficiency of solar panels. Solar FlexRack stated in October that its solar trackers had been deployed in more than 80 solar projects on California farms, including a 2.82-MW installation for Danell Brothers Dairy south of Hanford (Figure 1). Renewable Solar Inc., which constructs commercial and agricultural solar projects in California, erected the array.

More than 150 dairy farms in California are now generating solar energy, as more and more of these energy-intensive industries turn to solar energy to lower operational expenses. “We’re delighted to have worked with Renewable Solar Inc. over the years to provide high-quality sustainable energy systems and corresponding cost reductions for California farm owners,” said Steve Daniel, executive vice president of Solar FlexRack. “We look forward to continuing our collaboration with Renewable Solar Inc. on further farm solar projects in support of California’s industry-leading renewable portfolio requirement.”

Series G racking from Solar FlexRack is available in both landscape and portrait orientations to enhance energy output based on location. The lateral bracing on the rack helps to support and square the racking system for easy installation. The horizontal rail bracket enables the horizontal rail to be installed without the use of bolts, reducing installation time. To enhance energy output, the rack can accept up to a 20% east-west slant.

Nextracker, situated in California, announced in early November that it was the first solar tracker (Figure 2) equipment and software vendor to achieve 50 GW in global exports. According to the corporation, their technology is employed in large solar power facilities in 40 nations.

Nextracker’s technological achievements include the NX Horizon solar tracker, which has a balanced mechanical design and produces bifacial energy. TrueCapture smart control software from the business is assisting utility-scale solar power facilities in mitigating power production decreases caused by cloud cover or when one row of panels casts a shadow over panels in surrounding rows.

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The Split Boost algorithm, which maximizes energy yield for split-cell silicon PV modules, is the business’s most recent breakthrough, according to the company. “We model Split Boost with our internal raytracing-based backtracking software where the shade tolerance of the module, as well as Split Boost operating mode, are baked into our row-to-row energy gain algorithm, so we can accurately estimate gains,” Defne Gun, a technical sales engineer for the company, wrote on the company’s website. We may predict TrueCapture performance at a given site using that site’s specific energy model, tracker geometry, and topography by employing the algorithms in’simulation mode’ before deployment to a solar plant.”

Tigo Energy, well known for its Flex MLPE systems, announced in September that its Energy Intelligence (EI) inverter and battery product lines were now accessible to residential solar installations in the United States. The new inverter and battery devices, according to the business, facilitate native integrations of the company’s solar and storage components and extend the Tigo Enhanced commercial and industrial solar collaboration program into the home sector.

“The new EI Battery and Inverter solutions include straightforward installation and commissioning as well as robust fleet management capabilities.” In turn, the end user will benefit from access to an abundance of resilient, renewable, and safe energy through a system that can be precisely tuned for pricing and performance,” stated Zvi Alon, CEO of Tigo Energy, in a news release.


Growth Requires Storage

Sharma emphasized that creating storage solutions in tandem with solar electricity will be critical to sustaining industry development. “Energy storage is still rather costly, and in many applications, it does not make economic sense.” [However], energy storage makes sense in home applications for resiliency, security, and powering during blackouts. It’s becoming increasingly crucial, especially as the occurrences of extreme weather rise. However, in order to truly unlock the next phase of solar, we require lower-cost storage across all applications.”

Companies are already offering items to help with domestic solar and storage. Tesla’s Powerwall is one of the most well-known examples; the Powerwall stores solar energy to offer backup power when the grid fails. PWRgenerator, a new type of DC generator intended to rapidly recharge Generac’s PWRcell Battery, was recently introduced by Generac Grid Services. During power outages, the DC-coupled PWRgenerator can allow the PWRcell Battery to keep a home powered for a longer amount of time.

The PWRgenerator links directly to the PWRcell inverter, resulting in “basically creating a domestic nano-grid allowing a residence to be entirely energy independent,” according to Generac. During the day, solar panels on a house give electricity to the house, with extra power charging the battery. The battery drains at night, and if the charge level hits 30%, the PWRgenerator—which can operate on either natural gas or propane—will switch on and fully charge the battery in roughly an hour.

Panasonic’s EverVolt household solar-plus-storage system; LG’s Home Battery RESU (Residential Energy Storage Unit); and smaller systems such as Jackery’s Solar Generator line and Goal Zero’s 6000X portable battery model are also available. In addition, advances in solar energy technology are being made in sectors like as automobile and building application PV; a slew of consumer devices with solar-charging capabilities; and wearable mobile power.

“Our sector is witnessing an acceleration in developments that increase solar [performance,” said Sharma, who added that “efficiency and aesthetics are becoming increasingly important.” “That’s where we’ll continue to see more improvements and breakthroughs.”

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