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Puzzling out and testing new ways to improve the efficiency of cadmium telluride (CdTe) polycrystalline thin-film photovoltaic materials is a typical day in the life of National Renewable Energy Laboratory (NREL) research scientists Matthew Reese and Craig Perkins. Like any good puzzlers, they bring curiosity and keen observation to the task. These skills led them, over time, to make an intriguing observation. In fact, their discovery may prove to be a boon for the next generation of several different types of thin-film solar cells.

When fragments of solar cell material are crystallized together, or “grown” — think of a piece of rock candy growing in layers in a cup of sugar — they create a polycrystalline solar cell. With many layers come many surfaces, where one layer ends and another begins. These surfaces can cause defects that restrict the freedom of electrons to move, reducing the cell’s efficiency. As the cells are grown, researchers can introduce specific compounds that minimize the loss of electrons at these defects, in a process called “passivation.”

Reese, Perkins, and Colorado School of Mines doctoral student Deborah McGott noticed that the three-dimensional (3D) CdTe solar cells’ surfaces appeared to be covered in a very thin, two-dimensional (2D) layer that naturally eliminated surface defects. This 2D passivation layer forms in sheets on the 3D light-absorbing layer as the cell is growing, in a standard processing technique that is used around the globe. Despite the ubiquity of this 2D passivation layer, it had not been observed or reported in the research literature. Reese, Perkins, and McGott believed 2D passivation was also occurring naturally in other thin-film solar cells, like copper indium gallium selenide (CIGS) and perovskite solar cells (PSCs). They realized that this observation could lead to the development of new methods to improve the performance of many types of polycrystalline thin-film cells.

To confirm their hypothesis, they discussed it with NREL colleagues in the CdTeCIGS, and PSC research groups. Through many informal discussions involving coffee, hallway chats, and impromptu meetings, Reese, Perkins, and McGott arrived at an “aha” moment. Their CdTe and CIGS colleagues confirmed that, while their research communities were not generally trying to perform 2D surface passivation in the 3D light-absorbing layer, it was, in fact, occurring. The PSC researchers said that they had noticed a 3D/2D passivation effect and were beginning to intentionally include compounds in device processing to improve performance. The “aha” moment took on even more significance.

“One of the unique things about NREL is that we have large groups of experts with different pools of knowledge working on CdTe, CIGS, and PSC technologies,” Reese said. “And we talk to each other! Confirming our hypothesis about naturally occurring 3D/2D passivation with our colleagues was easy because we share the successes and setbacks of our diverse research in an ongoing, informal, and collaborative way. We learn from each other. It is not something that typically happens in academic or for-profit-based polycrystalline thin-film solar cell research, where information is closely held, and researchers tend to remain siloed in their specific technology.”

The details of Reese, Perkins, and McGott’s discovery are presented in the article “3D/2D passivation as a secret to success for polycrystalline thin-film solar cells,” published in the journal Joule.

Supporting Evidence in the Literature

To confirm their findings, McGott conducted an extensive literature search and found considerable supporting evidence. The literature confirmed the presence of passivating 2D compounds in each of the CdTe, CIGS, and PSC technologies. No mention was made, however, of the 2D compounds’ ability to improve device performance in CdTe and CIGS technologies. While many articles on PSC technologies noted the naturally occurring 3D/2D passivation effect and discussed efforts to intentionally include specific compounds in device processing, none suggested that this effect might be active in other polycrystalline thin-film photovoltaic technologies.

Polycrystalline thin-film solar cells are made by depositing thin layers, or a thin film, of photovoltaic material on a backing of glass, plastic, or metal. Thin-film solar cells are inexpensive, and many people are familiar with their more unique applications. They can be mounted on curved surfaces — to power consumer goods, for example — or laminated on window glass to produce electricity while letting light through. The largest market for thin-film solar cell applications, however, is for CdTe thin film on rigid glass to make solar modules. CdTe modules are deployed at utility scale, where they compete directly with conventional silicon solar modules. Currently, commercial thin-film modules are generally less efficient than the best single crystal silicon solar modules, making performance improvements a high priority for polycrystalline thin-film researchers.

Key Properties of 2D Materials

Reese, Perkins, and McGott’s team used surface science techniques combined with crystal growth experiments to show that the 2D layers existed at and passivated 3D absorber surfaces in the three leading polycrystalline thin-film photovoltaic technologies. They then analyzed the key properties of successful 2D materials and developed a set of principles for selecting passivating compounds.

Finally, the team outlined key design strategies that will allow 3D/2D passivation to be employed in polycrystalline thin-film photovoltaic technologies more generally. This is particularly important because each 3D material requires a specific passivation approach.

The literature results, combined with lab-based observations, show that 3D/2D passivation may be the secret to success in enabling next-generation thin-film solar cells, particularly if researchers freely share the knowledge developed for each technology. The lack of 3D/2D passivation may even shed light on the stalled performance improvements of some polycrystalline technologies such gallium arsenide. By drawing parallels between the three technologies, Reese, Perkins, and McGott hope to demonstrate how the knowledge developed in each can — and should — be leveraged by other technologies, an approach that is seldom seen in polycrystalline thin-film solar cell research.

CdTe, CIGS, and PSC thin-film research at NREL is funded by the Department of Energy’s Solar Energy Technologies Office. Additional funding for Reese and McGott’s research is provided by the Department of Defense’s Office of Naval Research.

Learn more about photovoltaic research at NREL.

Article courtesy of the NREL, The U.S. Department of Energy.


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Nissan feels the heat from BYD’s EV price war in China

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Nissan feels the heat from BYD's EV price war in China

Nissan is the latest victim of BYD’s “liberation battle” against gas-powered cars. After BYD’s aggressive price cuts this year, Nissan is shutting down a factory in China as it struggles to keep up.

As is the case for many legacy automakers, China is a critical sales market for Nissan. Nearly a third of Nissan’s global sales and net profits are from China.

After slipping out of the top five automakers (by market share) in China in 2022, Nissan’s woes are worsening. Nissan’s sales fell 16% in China last year and the trend has continued into 2024.

Nissan’s sales fell another 2.8% last month, with 64,233 vehicles sold in China. The company cut guidance by 23% last year, with 800,000 vehicle sales expected in fiscal 2024. According to Nikkei, Nissan will do so with one less factory.

Nissan is closing the doors to its plant in Changzhou as the factory is building more cars than it can sell.

The facility accounts for about 8% of Nissan’s production capacity in China, with an annual capacity of around 130,000 units. According to the report, the plant shuts down on Friday.

Nissan-BYD's-EV
Nissan Ariya electric SUV (Source: Nissan)

Under its joint venture with China’s Dongfeng Motor, Nissan has eight plants in the region. Its total annual capacity is around 1.6 million, double Nissan’s projected sales figures for fiscal 2024.

Nissan shuts down China plant amid BYD’s EV price war

The plant shutdown comes as Nissan struggles to keep up in an increasingly competitive China EV market.

China’s largest automaker, BYD, kicked off a “liberation battle” against ICE vehicles earlier this year. The goal is to continue taking market share from gas-powered cars with lower-priced EVs. So far, it seems to be working.

Nissan-BYD's-EVs
BYD (Dolphin Mini) Seagull EV (Source: Nissan)

BYD has drastically cut prices while introducing lower-priced EV models. Its cheapest, the Seagull EV, starts under $10,000 (69,800 yuan).

BYD’s CEO, Wang Chaunfu, said EVs have entered “the knockout round” and that the next two years will be critical for automakers to catch up.

With lower-priced, more advanced models hitting the market, BYD sees joint venture brands (like Nissan’s) market share falling from around 40% to 10% in China.

Nissan isn’t the only legacy automaker feeling the heat. Japanese rivals Toyota, Mitsubishi, and Honda have also pulled back in China amid slumping sales.

Nissan-BYD's-EV
Nissan EV concepts (Source: Nissan)

Meanwhile, BYD looks to expand its global footprint after outgrowing China’s EV market. BYD is closing in on a deal for a plant in Mexico that would be among the biggest in the country. The company expects to sell 50,000 vehicles in Mexico this year.

BYD is also expanding on Nissan and Toyota’s home turf. According to data from the Japan Automobile Importers Association, BYD accounted for over 20% of Japan’s EV imports in January.

With longer-range, lower-priced models rolling out, BYD’s momentum is expected to continue. China’s leading automaker is also expanding into new segments like pickups (check out the new Shark PHEV), mid-size electric SUVs, and luxury.

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Tesla Model 3 Long Range costs $3,200 more to finance than last week

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Tesla Model 3 Long Range costs ,200 more to finance than last week

Tesla scrapped promotional financing on the Model 3 Long Range this week after it became eligible for the $7,500 federal tax credit.

As Electrek reported on June 17, Tesla and the IRS confirmed that the Model 3 Long Range All-Wheel Drive is now eligible for the full tax credit. Today, Tesla is pricing the EV’s upfront purchase price at just $34,990 – $1,000 more than the Model 3 Rear Wheel Drive – including the federal tax credit and an estimated five-year gas savings of $5,000.

The Model 3 Rear Wheel Drive still doesn’t qualify for the federal tax credit because it uses LFP battery cells from China.

The Model 3 Long Range is now listed at 6.39% APR on loans up to 72 months. The Model 3 Rear-Wheel Drive continues to offer 1.99% APR for 36 months with a 60-month option at 2.99%.

Even though the Model 3 Long Range is now $7,500 cheaper, the higher interest rate is a bit of a party pooper, as it eats up potential savings. The folks at CarsDirect estimated that on a five-year loan, thanks to the 6.39% interest rate, the Model 3 Long Range has more of a $4,200 advantage than a $7,500 advantage.

If you’re eligible for the federal tax credit, the Model 3 Long Range is cheaper than before but costs around $3,200 more to finance through Tesla than last week. CarsDirect suggests comparing your options carefully if you’re shopping for a Model 3 Long Range. 

Click here to find a local dealer that may have the Model 3 in stock –affiliate link


If you live in an area that has frequent natural disaster events, and are interested in making your home more resilient to power outages, consider going solar and adding a battery storage system. To make sure you find a trusted, reliable solar installer near you that offers competitive pricing, check out EnergySage, a free service that makes it easy for you to go solar. They have hundreds of pre-vetted solar installers competing for your business, ensuring you get high quality solutions and save 20-30% compared to going it alone. Plus, it’s free to use and you won’t get sales calls until you select an installer and share your phone number with them.

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Utah is getting 20 ‘hyper-fast’ Electrify America EV charging stations

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Utah is getting 20 'hyper-fast' Electrify America EV charging stations

Electrify America and electric utility Rocky Mountain Power have rolled out the first of 20 DC fast charging stations in Utah.

Electrify Commercial, a business unit of Electrify America, and Rocky Mountain Power, a division of PacifiCorp, are deploying more than 80 chargers at 15 DC fast charging stations in the Salt Lake City area and five DC fast charging stations in surrounding regions.

So far, four charging stations have come online in Millcreek, Vernal, Moab, and Kimball Junction.

Rocky Mountain Power, the only rate-regulated public utility providing electric service in Utah, will own the new charging stations. Each will have “hyper-fast” chargers capable of speeds up to 350 kW. The utility will set the pricing and Rocky Mountain Power utility customers get a discounted rate.

Since 2016, Rocky Mountain Power has installed more than 120 DC fast chargers in Utah and completed an electric highway corridor along I-15, Utah’s primary and only north-south interstate highway. It’s also facilitated the installation of more than 3,000 Level 2 chargers for workplaces, retail, and multifamily housing. The utility is spending $50 million to install EV charging infrastructure across Utah.

All 20 of Utah’s new DC fast charging stations will be on Electrify America’s coast-to-coast “locate a charger” map, which includes more than 950 stations and over 4,250 chargers in the US and Canada. Drivers will be able to access and pay for charging on Rocky Mountain Power’s chargers through the Electrify America mobile app.

Read more: Here’s what Electrify America’s EV charging plans are for 2024


To limit power outages and make your home more resilient, consider going solar with a battery storage system. In order to find a trusted, reliable solar installer near you that offers competitive pricing, check out EnergySage, a free service that makes it easy for you to go solar. They have hundreds of pre-vetted solar installers competing for your business, ensuring you get high quality solutions and save 20-30% compared to going it alone. Plus, it’s free to use and you won’t get sales calls until you select an installer and you share your phone number with them.

Your personalized solar quotes are easy to compare online and you’ll get access to unbiased Energy Advisers to help you every step of the way. Get started here. –affiliate link*

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