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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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5+ year review: The e-bike gear that’s lasted me half a decade or more

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5+ year review: The e-bike gear that's lasted me half a decade or more

When it comes to e-bike gear, most of us have been burned before. That “waterproof” pannier that started leaking after the first storm, the multitool that rounded out on its tenth bolt, the lights that faded faster than a dying AA battery. I’ve had my share of disappointments. But over the past decade of nearly daily riding, there’s a small handful of e-bike tools and accessories that have stood the test of time. I’m talking half a decade or more of constant use, surviving rain, dust, sun, and the occasional crash, and still going strong.

As an e-bike reviewer who tests an untold number of new, shiny bikes and gadgets each year, I often share my early experiences with a new product. But rarely do I get to do a long-term review – and I mean years. So here’s a chance for me to look back at the gear I’ve incorporated into my car-free life for over half a decade.

These aren’t just “pretty good” products. These are the pieces of gear that have earned a permanent spot on my bike or in my toolkit. They’ve been with me through countless commutes, late-night rides, weekend tours, international trips, and enough roadside repairs to fill a small notebook. And even after years of abuse, they still do their job without complaint.

So, whether you’re building your first e-bike setup or replacing gear that gave up the ghost too soon, here’s my long-term, battle-tested list of e-bike products that have survived five years of heavy use and are still worth every penny.

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Topeak Ratchet Stick

The Topeak Ratchet Stick might just be my all-time favorite bike tool.

It doesn’t cover every possible repair, but it includes the hex driver sizes you’ll use for most routine jobs, like adjusting brakes, saddles, racks, and so on. There’s also a second plastic holder with extra bits, mostly Torx drivers, but I rarely need them. In fact, I’m not even sure where that holder is anymore. I haven’t seen it in years and I’d guess it’s probably buried somewhere in my parts bin. The five bits stored in the handle of the tool are all I use regularly (2, 3, 4, 5, and 6mm).

Even without the extras, the core tool is a game-changer. All your most-used bits are right there, ready to pop into the compact ratchet, which makes tightening bolts far faster than fiddling with a standard Allen key. No more lifting and resetting every partial turn – the ratchet lets you work continuously, and the quick direction lever flips between tightening and loosening instantly. Especially for bolts with Loctite that require spending a minute or two to slowly drive down a dozen threads a half turn at a time with an Allen key, the ratchet stick takes care of it in 10 seconds.

And for cases where you don’t want the ratchet part, the end of the tool holds the bits like a typical Allen key, so you get the quick turning feature for fast bolt driving, then the ratchet action for quick tightening.

At $45, it’s not cheap, and is in fact quite a bit more expensive than the free set of Allen wrenches that came with your bike. But if you work on bikes as much as I do, it’s worth every penny. Saving the skin on your knuckles is worth it, alone.

This tool isn’t as nice and time-saving as the Topeak Ratchet Stick above, but it is significantly cheaper at $12, and it has some advantages. While you still have to take it out, turn it 180 degrees, put it back in, tighten, and repeat, it’s also a lot shorter which make it better for carrying.

My go-to tool for riding, this one slips easily in my jeans pocket-watch pocket and that also keeps it riding higher so it doesn’t drop down near my thigh. As much as I love my Topeak Ratchet Stick, that one is awkward to carry in a pocket because of its length, so I find it spends more time on my tool shelf for stationary work like repairs and bike building than mobile work like trail-side adjustments.

The AWS tool, on the other hand, is the perfect grab-and-go Allen key set. It’s small, it’s well-made, and it just simply works.

I’ve got a few of these, but the longest-lived one has been with me for over five years. It’s the tool I reach for first when I’m heading out on a ride and want to make sure I have a tool in my hand.

AfterShockz Trekz Air bone conduction headphones

I refuse to wear earbuds or “normal” headphones on a bike under basically any scenario. It started in the military when we weren’t allowed to wear earbuds when off-base for situational awareness reasons, and the sensibility stuck with me.

There’s no situation where I’d be on a bike and think, “You know what would make this experience better? Not being able to hear dangers around me.” Whether commuting in the city or enjoying a nature ride, I either need to hear potential threats or I just want to be able to take in the sounds of my environment.

And yet, it can still be nice to listen to a podcast or music on a long fitness ride or run. So I prefer bone conduction headphones. These leave your ears open for ambient noises, and instead conduct the sound right through your skull. Is the audio quality as good as over-the-ear noise-cancelling headphones? Of course not. But I’d rather be alive while listening to moderate quality audio than get those deep bases right up to the moment I’m being pancaked by an Isuzu.

I’ve had these headphones since 2019, and they are still going strong. I don’t only use them for riding – in fact I use them even more often for running. I can get around five or six 45-minute running sessions in before they need a charge, so the battery is obviously worn down from when they were new, but the darn things just continue to work. Other than needing to charge more frequently, they’re as good as new.

I’m not sure they even make this exact model anymore, but Aftershockz seems to have many different models now, and this one looks close.

Cotopaxi Allpa 35 backpack

If I could have only one backpack in my life (I shudder at the thought), it would be this one. Cotopaxi is a great brand for a lot of reasons, chief among them the build quality and their commitment to sustainability, but the Allpa 35L is the creme de la creme for me.

This is more of a travel bag, and I’ve used it a ton that way. I’ve had this thing on countless trips to countless countries (I lost track at around 11 or 12) and I’ve beaten the hell out of it. I’ve taken it on jarring bikes rides, I’ve lashed it to the pillion seat on 100 MPH electric motorcycles, I’ve dragged it across airport floors, I’ve tossed it by the zipper pulls on the rare occasion that I’m in a rush and that’s the closest thing I can grab… Basically, it’s lived a hard life with me full of use and abuse. And yet, here we are, six years later.

The only wear it’s really showing is the rubberized coating on the front (and I’d even recommend getting the version without the rubberized front for that reason), but it’s merely aesthetic wear that doesn’t impact its functionality. The bag still works as well as the day I got it, which was nearly 2,000 days ago. Over $200 isn’t cheap for a bag, but when it lasts as long as this one, it’s a lot cheaper than buying a $45 bag every year.

This big boy probably isn’t the bag you want for a quick bike ride, but for longer trips like bikepacking and travel, it’s the only bag I take. Plus it also comes in smaller sizes if you don’t carry as much gear as I sometimes do.

See it in action on a motorcycle trip I took a few years ago, below.

Elite Borson bicycle travel bag

This Elite Borson bike bag has carried bikes internationally for me since 2020. It’s gotten tossed around. It’s gotten beat up. A few years ago it arrived at one international airport with one of its four wheels mysteriously missing. And yet, here we are. It keeps on trucking, and so I keep abusing it.

I’ve never once had a bike that I shipped in it arrive damaged. It’s hard where it needs to be, soft where it should be, and just gets the job done.

I love that despite all of its protection, it also packs down to around 1/4 of its size when not in use (which is good since this bag is HUGE). The only big downside to it is having to always go to the oversize bag drop/baggage claim belt at airports, but such is the life of a destination bike rider.

I’ve seen lots of cheaper bicycle bags out there, but if you’re going to travel with a heavy e-bike and you don’t want it getting damaged, this beast of a bike bag will get it there.

Oh yea, and about that wheel. It’s a bummer that I lost a caster wheel somewhere along the way. But the bag is so strong and the bottom of the bag is so tough that I have used it for years now with just three wheels. That corner of the bag simply drags along the ground.

I guess eventually it will wear down there, but who knows how long that will take. Maybe we will have hoverbikes by then.

Mirrycle bar-end mirror

There are a lot of bicycle mirrors out there, but the Mirrycle bar end mirror has long been a favorite of mine. I’ve got several, but the oldest is from around 2013. That’s a darn long time!

These are no-nonsense mirrors that don’t shake, don’t vibrate, and lock in strongly to just about any bike handlebar.

I can’t stop wobbly mirrors or models that you have to readjust after every big bump. The Mirrycle bar end mirror always stays where I put it unless I smack it into something, and I can’t really blame it in that case.

There’s not much else to say about it. It just works. It shows you what’s behind you. And it’s been doing so for me over the last 12 years. I’d say that’s a solid value for $15.

The takeaway

In a world where most products seem designed to fail just after the warranty expires, finding gear that lasts this long feels like discovering a secret. These tools and accessories are beyond reliable; they’ve become trusted companions on many of my daily rides.

Of course, nothing lasts forever. But if these items can survive my daily abuse for over half a decade, they’ve got a fighting chance of lasting through whatever you throw at them. And in my book, that makes them worth not just buying, but keeping for the long haul.

Here’s to fewer broken parts, fewer replacements, and more gear that’s built to ride as far and as long as we do.

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Volkswagen is delaying the Golf EV, an electric SUV, and more

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Volkswagen is delaying the Golf EV, an electric SUV, and more

The iconic hatch is still going all-electric, but not soon enough. Volkswagen is delaying the electric Golf, an upcoming electric SUV, and more, due to rising costs.

Why is Volkswagen delaying the Golf EV?

Volkswagen is going back to its roots with plans to revive some of its top-selling nameplates, including the Golf and T-Roc, as battery electric vehicles.

Although we expected to see the electric hatch arrive in 2028, it looks like it will actually be closer to the end of the decade now.

Volkswagen is pushing back the launch date by about nine months, according to sources close to the matter (via Bloomberg). The setback is reportedly due to rising costs from the restructuring at its Wolfsburg plant in Germany, where the Golf is produced.

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Last year, the European auto giant agreed to shift production of the gas-powered Golf to Mexico, while the EV version was set to replace it as soon as 2027.

According to the sources, Volkswagen is delaying the Golf EV due to budget constraints associated with the plant retooling.

Volkswagen-delaying-Golf-EV
Volkswagen’s production plans (Source: Volkswagen Group)

VW is upgrading the facility to prepare it for its next-generation EVs, including the Golf. The electric T-Roc is also being pushed back, the sources claimed

Plans to move the current Golf to Mexico have been delayed as the costs of new tech and more to build the two new EV models need to be pushed to a different spending period.

Volkswagen-ID.Cross-affordable-SUV
Volkswagen brand CEO Thomas Schäfer and the ID.Cross affordable electric SUV concept (Source: Volkswagen AG)

The delay comes as tensions at the Wolfsburg plant are rising. According to the sources, production lines are at a standstill due to technical and equipment failures. Output at the facility could fall by thousands of units a week, the sources claim.

Volkswagen plans to launch a new family of more affordable, entry-level electric vehicles to keep pace with BYD and other Chinese EV makers that are quickly gaining market share.

Volkswagen-delaying-Golf-EV
Volkswagen ID.Polo and ID.Polo GTI (Source: Volkswagen)

At IAA Mobility 2025 last week, Volkswagen showcased the upcoming lineup, including the ID.Polo and ID.Cross, an electric sibling to the T-TRoc.

The ID.Polo is expected to debut in the first half of next year, starting at around €25,000 ($30,000), followed by the ID.Cross, and a smaller, entry-level EV based on the ID.EVERY1 concept. It looks like we won’t see the electric Golf until closer to the end of the decade now.

Volkswagen is assessing its budget from 2026 to 2030, which could include an around €160 billion ($188 billion) budget to address the issues.

Electrek’s Take

Although Volkswagen has big plans to fend off the incoming wave of low-cost EVs from BYD and other automakers from China, when will we actually see them?

The ID.Polo is due out in the first half of 2026, marking the start of the next generation of Volkswagen. That’s if it launches on time.

Delaying the electric Golf until 2029, at the earliest, will only give BYD and other brands more time to grab market share. BYD is already starting to gain a foothold in Europe, but sales are expected to accelerate as it expands its lineup and distribution network.

European automakers, including VW, BMW, and Mercedes-Benz, are promising that more affordable electric vehicles are on the way, but they’d better get going. Otherwise, it could be too little, too late.

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Elon Musk sends Tesla’s stock soaring on $1 billion purchase amid suspicious transactions

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Elon Musk sends Tesla's stock soaring on  billion purchase amid suspicious transactions

Elon Musk bought over $1 billion worth of Tesla’s stock, sending the share price soaring. The move comes amid highly suspicious option transactions on Tesla’s stock.

Today, Tesla disclosed in an SEC filing that Elon Musk bought Tesla stock for the first time in 5 years.

He purchased 2.5 million shares worth roughly $1 billion on Friday, which explained why the stock surged 7% that day on no news.

Tesla insiders have been consistently selling Tesla stock for the past decade, with virtually no one buying anything other than Joe Gebbia, a friend of Musk known as the co-founder of Airbnb and a board member at Tesla, who bought $1 million worth of stocks.

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The last time Musk himself traded the stock was to sell tens of billions worth to finance his acquisition of Twitter.

Now, buying the stock is seen as a positive reversal of the insider trading trend.

However, it comes at a highly suspicious moment.

On Friday, when Musk was boosting Tesla’s stock price with 25 stock purchases worth more than $1 billion, some people were making some suspicious bets that the stock would surge in the short term without any known catalyst.

The stock option market on Tesla’s stock was wild on Friday. Some people made some wild bets like buying thousands of call contracts at a strike pirce of $430 with an expiry date within two weeks:

You will sometimes see this type of short-term expiry contracts ahead of earnings when large stock price swings are likely in one direction or the other. However, Tesla has no earnings or catalysts of any type coming in the next two weeks.

These contracts have surged in value by 1,000% following the revelation of Musk’s stock purchase.

Electrek’s Take

People bet millions on this short-term swing in Tesla stock. To be clear, this doesn’t necessarily represent a strong conviction in Tesla’s stock increasing in value; it is a bet on a very short-term swing up.

They were either extremely lucky that Musk decided to time his stock purchase this way, or they knew he was buying because he had told them.

With the SEC being virtually absent for the past year and allowing rampant fraud in the market, I wouldn’t be surprised if some shenanigans were going on here.

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