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After a decade of leadership, voters are poised to overturn two of its biggest achievements. What happened?

Twenty years ago, you could still get away with calling Redmond, Washington, an equestrian town. White fences parceled off ranches and hobby farms where horses grazed under dripping evergreen trees; you could buy live chicks, alfalfa, and Stetson hats in stores downtown. It wasn’t even unusual for Redmond voters to send Republicans to represent their zip code in the state legislature, despite the city being located in blue King County.
The Redmond of today, on the other hand, looks far more like what you’d expect from an affluent (and now staunchly progressive) suburb of Seattle. A cannabis dispensary with a pride flag and a “Black Lives Matter” sign in the window has replaced Work and Western Wear, and the new high-performing magnet school happens to share a name with one of the most popular cars in the neighborhood: Tesla. But Washington is a state full of contradictions, and among Redmond’s few remaining farms is one registered under the winkingly libertarian name of “Galt Valley Ranch LLC.” It belongs to a multimillionaire who has almost single-handedly bankrolled the most significant challenge yet to Washington’s standing as a national climate leader.
Andrew Villeneuve, the founder of the Northwest Progressive Institute, a left-wing think tank also based in Redmond, told me he’s struggled to get voters to pay attention to ballot measures in the past. “I’ve had no such awareness issues this year,” he said. “Nobody’s like ‘Who’s Brian Heywood?’”
A hedge fund manager, multimillionaire, and recent California transplant, Heywood has in short order made himself the supervillain of Washington’s left. His Joker arc into politics involves fleeing the liberal dystopia of the Golden State in 2010 for the no-income-tax refuge of Washington, only to discover that Olympia was progressive, too. This year, he set out to personally “fix stupid things” in his adopted state by spending $6 million out of pocket on a signature-gathering campaign that ultimately landed four conservative initiatives on Washington’s general election ballot. (His campaign, Let’s Go Washington, is also allusively named, although Heywood told The Seattle Times that he is not a MAGA supporter.)
Two of the four ballot measures Heywood has willed before voters this November address standard small-government gripes: One would repeal the capital gains tax, and the other would allow workers to opt out of the state’s long-term care payroll tax. Others, however, will ask Washingtonians to vote directly on whether to repeal the state’s landmark cap-and-invest carbon-trading program (I-2117) or block its transition away from natural gas (I-2066).
“We’ve faced initiatives like these before,” Villeneuve told me, “but what is different is how many of them are coming at once.”
As in many Western states, it’s relatively easy for a motivated individual with means to collect the roughly 320,000 signatures needed for a petition to end up on the ballot in Washington. (Contract workers are paid up to $5 per signature, and they often descend on ferry lines, where bored motorists can be talked into putting down their names as they wait for the next boat.) But while rich activists have leveraged this system in the past — Washingtonians may remember the name Tim Eyman — the outcome of the ballot measures before voters this fall will be closely watched by other states and legislatures to gauge how directly popular bold climate progress really is.
“What happens in Washington will certainly have an impact on what happens around the rest of the country,” Leah Missik, the Washington deputy policy director at the clean energy nonprofit Climate Solutions, who also serves on the executive board of the No on 2066 campaign, told me. She added, “If these [laws] are in any way repealed or weakened, that is a sign to other states, and I think it would be incredibly damaging and incredibly unfortunate.”
Though politics in Washington have long been conservation-minded and, shall we say, crunchy (I grew up in Redmond), the state really began to stand out as a leader in progressive climate policy with Governor Jay Inslee’s election in 2013. During Inslee’s tenure, Washington committed to one of the most aggressive 100% clean energy pathways in the country, passed a wide-ranging building emissions law that RMI described as “significantly [raising] the level of ambition on what might be possible for other states,” and in 2023 enacted its landmark cap-and-invest program, called the Climate Commitment Act, which has generated over $2 billion in state revenue so far for transit projects, decarbonization initiatives, and clean air and water programs. Washington has even been credited with inspiring some of President Biden’s climate actions in office.
With Inslee, a Democrat, retiring at the end of this term, Let’s Go Washington’s campaign begins to appear designed to dismantle his legacy while proposing little in the way of alternatives. Hallie Balch, the communications director, denied this allegation in an emailed statement, telling me the initiatives “promote choice and affordability.” The cap-and-invest program, for example, “has not done what the governor said it would do,” she said, and “there are no metrics in place to track [its] success.”
Though the CCA’s cap covers about 75% of the state’s total greenhouse gas emissions, it’s true that we’re still a few years away from having a clear picture of the program’s results. (The law’s first compliance deadline for polluters isn’t until this November.) “The CCA has only been around for almost two years at this point, and so we haven’t yet seen the big emissions declines,” Emily Moore, the director of the climate and energy program at the Sightline Institute, a nonpartisan sustainability think tank that does not take an official position on initiatives, told me. “But what we are seeing,” she added, “is the money that it has generated for a whole suite of climate-friendly and community-friendly projects.”
There isn’t a revenue source remotely comparable to cap-and-invest available to fund the state’s transit, infrastructure, and community projects if the program goes away, meaning a repeal would have a dramatic impact on everything from bus service to salmon recovery projects to local heat pump and induction stove rebates, with most likely getting the axe. The program is also one of the main levers Washington has to reach its goal of reducing emissions 95% below 1990 levels by 2050. As one person involved in crafting the CCA described the upcoming vote on I-2117 to me, it’s “life or death for climate action in Washington.”
That’s partially because I-2117 wouldn’t only repeal the CCA; it would also bar the state and any municipality therein from implementing a new climate tax or cap-and-invest program at any point in the future. When asked what an alternative might be last week during a debate at Seattle University’s Department of Public Affairs and Nonprofit Leadership, Heywood vaguely proposed “something that works.”
“We always knew we were going to have to defend this program at the ballot box,” Joe Fitzgibbon, the majority leader of Washington’s House of Representatives and the chair of the House Environment and Energy Committee, who helped create the CCA, told me. He admitted that he’d expected such a defense to take the form of legislative elections, but 2022 came and went without a single backer of the CCA losing their seat. “I guess in hindsight, I thought we were out of the woods,” Fitzgibbon said.
Let’s Go Washington has labeled CCA a “hidden gas tax” and, bundled with its other initiatives, is running on the slogan “vote yes, pay less.” I-2117 is already the most expensive ballot measure campaign of this election cycle — and the most controversial, with Heywood campaigning at gas stations offering discounted gas, which opponents say violates vote-buying anti-bribery laws. But opposition to the initiative has also rallied a remarkable and unprecedented coalition of strange bedfellows in defense of the CCA, including over 500 businesses, environmental groups, health care organizations, faith leaders, tribes — as well as more than 30 breweries, “a very important coalition member in the state of Washington,” as No on I-2117’s communication director Kelsey Nyland quipped to me. Jane Fonda recently swung through the state to stump for I-2117; the ‘no’ campaign even has the support of the Green Jobs PAC, whose contributors include Shell and BP.
Almost all the advocates I spoke to about I-2117 were feeling optimistic ahead of Washington ballots going out at the end of this week, with the most recent Cascade PBS/Elway poll on the initiative showing support has dropped slightly since May; 46% now say they would vote no, over 30% who would vote yes. (Heywood has pointed optimistically to the number of undecided voters this leaves.) Still, it seems pretty unlikely that Washingtonians will repeal their cap-and-invest program.
I-2066 is a different story.
To the immense frustration of its opponents, Let’s Go Washington touts I-2066 as “Stop the Gas Ban.” The measure was only certified for the ballot in July, compared to January for 2117, meaning that organizers have had much less time to mobilize — several major national green groups, including Defenders of Wildlife and the Environmental Defense Action Fund, confirmed to me that they’d endorsed No on I-2117 but not considered a position on I-2066 — and are on the back foot to combat misinformation.
For one thing, there is no gas ban: I-2066, rather, would repeal parts of a Washington law directing its largest utility, Puget Sound Energy, to consider electrification alternatives before installing new gas pipes; scuttle a pilot effort to promote thermal energy networks as a gas alternative; and, most starkly, it would bar cities and towns, as well as Washington’s energy code, from “prohibiting, penalizing, or discouraging” gas appliances in buildings. “Discouraging” does a lot of work here. For example, Seattle’s building emissions performance standard, which doesn’t ban gas but nudges large developments toward a 2050 net-zero emissions target, could be in jeopardy.
Still, all of this is a lot to expect voters to sort through in the few minutes they might spend filling in the bubbles in their ballot, especially when Let’s Go Washington is making out its message to sound like one simply about energy choice. Add the opaque triple-negative climate campaigners have to sell (“vote no on a ban on banning gas”), and the messaging headaches grow more severe.
Earlier this month, the editorial board for the largest media outlet in Washington, The Seattle Times, endorsed a yes vote on I-2066, arguing for a slower transition away from fossil fuels that leans more heavily on natural gas. “Unfortunately, we are up against a network of fossil fuel corporations and their allies who have a lot of money and who are very invested in the status quo because it perpetuates their wealth and their influence,” Missik, who’s involved with the No on I-2066 campaign, told me, pointing to the Building Industry Association as well as Northwest Natural, National Propane Gas Association, and Koch Industries, who have backed the other side. I-2066 is also polling much better than I-2117; as of September, 47% of voters said they would vote yes, compared to 29% who said they’d vote no.
Rather than interpret those numbers as the electorate’s backlash to Washington’s climate progress, advocates argue they indicate how fossil fuel groups have successfully capitalized on the door propped open by Heywoods’s signature-gathering campaigns. It’s “because one guy opened his wallet; it is that simple,” Villeneuve, the founder of the Northwest Progressive Institute, said. “There is no grassroots movement to overturn these laws; it doesn’t exist. Brian Heywood brought this entire thing into being.” Or, as Missik put it: “Most Washingtons do believe in climate progress, whether or not this will be overridden by money. I sure hope not.”
All of this ultimately brings us back to the question of what Heywood’s whole deal is. With the singular exception of I-2066, his $6 million initiatives seem mostly doomed.
Some I spoke to floated the idea that Heywood and his allies are using Washington as a testing ground for dismantling climate action and seeing what sticks. “If it can happen here, it can happen anywhere: It can happen in California, it can happen in Colorado, it can happen in New York, it can happen in all these states that have passed really strong climate policies,” Caitlin Krenn, the climate and clean energy director of the nonprofit Washington Conservation Action, told me.
But there are other rumors, too. The Washington State Standard’s Jerry Cornfield recently quoted a local GOP chair calling Heywood’s initiatives “a powerful tool” that will “help get Republicans elected” — essentially, a turnout generator. (“We certainly want to see as many people as are eligible to vote exercise their right to make their voices heard, but our top priority is to educate voters about what's at stake with the initiatives this November,” Balch told me in response.) And then there is Heywood’s ranch. Republicans have long cosplayed as rural farmers and cowboys to tap into the masculine conservative fantasy of rugged individualism (what Texas Monthly once called “authenticity drag”). It’s essentially an image-building exercise — perhaps not so unlike positioning yourself as the guy who tried to rein in the state’s runaway Dems.
So far, Heywood has dodged questions about whether he plans to run for governor, and his campaign told me he “isn't using the initiatives as anything other than a way to bring broken policies directly to the people to vote on.” But with this year’s ballots going out to Washington voters today, it’s also a question for another time.
Regardless of what happens, many of the organizers I spoke to rejected the framing of Washington voters cooling on climate. One went as far as to tell me that the time, attention, and money Heywood has spent trying to roll back Washington’s progress is the highest compliment of all. “This is part of the process of doing big things,” Isaac Kastama, who was involved in enacting the CCA and now works for the advocacy group Clean and Prosperous Washington, told me. “If it’s not big and if it goes undetected, that probably means you’re not doing something serious enough.”
Editor’s note: This story has been updated to clarify the scope of I-2117 and correct what Let’s Go Washington has termed a “hidden gas tax.”
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New research from Climate Central estimates the rise in heat-related emergency room visits due to climate change.
2027 is very likely to be the hottest year ever recorded. Though heat was the climate story of the summer — the ocean heat that dictates the severity of El Niño; the back-to-back heat domes in Europe that killed an estimated 35,000 people; the U.S. experiencing its hottest month in 130 years, breaking the Dust Bowl record — what lies ahead will be, in all likelihood, nothing our species has ever experienced before.
We need to get better at understanding and adapting to extreme heat because lives are on the line. But there is also a lot of bad stuff that happens to people before they actually die from the heat. While excess mortality rates are an important (albeit tricky) way of measuring how bad a heat wave is, climate change-related heat is also fueling an increase in emergency room visits, new peer-reviewed research by Climate Central found.
In a study released Wednesday looking at warm months in the years 2018 to 2025, Climate Central found that the observed rate of heat-related ER visits averaged 130 per 100,000 total visits, compared to a modeled rate of just 95 visits under counterfactual temperature conditions — that is, what temperatures would be without the influence of human-caused climate change. That means human-caused planetary warming directly accounts for about 35 visits per 100,000, or 27% of heat-related emergencies.
While the Sun Belt had the highest overall rates of heat-related ER visits, as expected, the largest relative climate fingerprint appeared in the Northeast (41%) and New England (37%), likely because these regions are far less acclimated to (or built for) extreme heat. Likewise, while July had the highest overall number of ER visits, being the hottest month of the year in the U.S., September showed the highest percentage attributable to climate change (33%) as heat impacts have begun to extend later into the fall.
Measuring emergency room visits might seem superfluous compared to measuring deaths, the latter being the more traditional headline number after an extreme weather-related tragedy. But Kristina Dahl, the vice president for science at Climate Central, told me that her group’s research is part of an emerging branch of attribution science called impact attribution.
“We’re trying to go beyond attributing the physical climate variables like high temperature and see how climate influence percolates into the whole chain of events,” Dahl said. “There’s a lot of literature that shows that heat-related illness increases when temperature increases, and there are a lot of studies that translate high temperatures into deaths and heat-related mortality. But we haven’t seen anything that looks at the lower-level health impacts related to heat exposure.”
Lower-level health impacts are crucial to understand, though. For one thing, more ER visits strain health systems in potentially lethal ways as wait times, premature discharges, and occupancy climb, resources dwindle, and care is rationed, earlier research has found.
Take the 2021 Pacific Northwest heat dome, the most extreme three days in the entire Climate Central record, with an observed rate of 6,763 heat-related ER visits per 100,000. About 1,834 of those visits, or 27%, are attributable to climate change, the researchers found. The Pacific Northwest “probably still would have seen a big spike in ER visits for heat-related illness during that event, even without climate change, because it was so extreme,” Dahl told me. But even a handful more heat patients than usual can gum up an ER, since treating conditions such as heat exhaustion and heat stroke requires lowering a person’s core body temperature slowly back to its normal range. Separate research has found that hospitals are more likely to discharge patients early to free up beds during heat waves, also raising mortality rates.
A visit to the ER isn’t just scary and disruptive; it can also be extremely expensive for whoever’s in the bed. “Our healthcare system is a really challenging system to navigate. It’s strained in a lot of ways, and people’s wallets are also strained because of it,” Dahl pointed out. Understanding how ER visits strain the health care system at large can also help administrators better stage ambulances and personnel ahead of extreme heat events — and invest in workforce expansion and infrastructure upgrades to prepare for the eventuality. Ideally, interventions can prevent people from end up in the hospital at all. Workplace heat protection policies, community cooling centers, and nature- and infrastructure-based cooling solutions are all vital.
There is a critical caveat to the Climate Central analysis, however: The data it uses to calculate heat-related ER visits comes from a Centers for Disease Control and Prevention initiative called the National Syndromic Surveillance Program. More than 85% of U.S. emergency departments report to the NSSP within 24 hours of a patient coming through the doors, conveying the chief complaint that a patient arrives with. “That could be someone saying, ‘I think I have heat exhaustion,’ or ‘I’m super dehydrated,’” Dahl said.
But because of that human element — and because a person having a heart attack isn’t likely to come in saying, “Hey guys, I think I’m having a cardiac event exacerbated by extreme heat” — Climate Central’s analysis faces the same limitations as other excess mortality reports that rely on reporting systems not designed to measure heat impacts. (This is also why NPR recently calculated that the number of people who die from extreme heat in the U.S. each year is likely five times greater than the official CDC numbers.)
When I pressed Dahl on the question, she agreed that Climate Central’s research offers “a conservative look” that could lead to an undercount. “We also know that in parts of the country where physicians don’t typically see heat illness, they tend to be a little less likely to code a visit as heat-related,” she added.
This isn’t a knock on Climate Central’s analysis — rather, it’s frightening to think that the real rates of heat-related hospital visits, much less all visits directly attributable to climate change, are probably much higher. Researchers, of course, need to be careful not to sensationalize, especially since sloppy data and poor science communication can lead to misconceptions and underestimations about the dangers of heat among the population. But it pays to understand what is happening; a surge in ER visits is another piece of the public health puzzle. Hopefully someone is paying attention, because the planet’s hottest summer — if prevailing trends bear out — is now only 41 weeks away.
Here are the major dates on the climate and energy calendar.
This is an edition of Heatmap Daily, an evening review of the day’s news written by our executive editor. Sign up for it here.
The Labor Day weekend is over, so today marks the unofficial start of fall in the United States — and my return to writing Heatmap Daily. Many thanks to Emily Pontecorvo for holding down the fort while I was on vacation.
As the seasons change (at least in a non-meteorological, non-astronomical capacity), I’ve been thinking about what the rest of the year might look like. Only 114 days separate us from the end of 2026, and between now and then, we're going to get answers about some of the country’s — and world’s — biggest ongoing climate and energy questions. By December 31, for instance, we’ll almost certainly know whether Congress has reached a deal on bipartisan permitting reform, and we’ll be watching a likely record-breaking El Niño kick into high gear around the world. The U.S. political system will also be gearing up for the next presidential election.
I’ll have more on some of the biggest questions I’m thinking about later this week, but first I wanted to lay out the map. Here’s a guide to the biggest remaining dates on the climate and energy calendar in 2026.
September 22 to September 28
Every year, world leaders descend on New York City for the UN General Assembly’s week of high-level meetings … at the same time that climate and energy wonks try to scrounge hotel rooms for New York Climate Week, the closest thing that the climate and decarbonization industrial-advocacy complex has to an annual confab.
This year, another event will be added to the mix. President Xi Jinping of China is supposedly skipping the UN meeting this year, but he will be staying just a few hundred miles away on the same exact days for what seems to be a Trump-hosted state visit in Washington, D.C. This will be the Chinese leader’s first state visit to America in more than a decade, and it will come, presumably, as U.S. relations with its neighbors and allies reach a recent nadir. Given the host country here, I wouldn’t expect to hear too much about climate change, but AI, trade, and Taiwan will all likely be on the schedule.
You can expect to hear a lot about climate change (and national energy policy, and the data center boom, and much more besides) at Heatmap House, our all-day gathering at New York Climate Week on September 23. Subscribers can register now, and speakers include former Vice President Al Gore, Secretary of Energy Chris Wright, and more.
October 4, 2026
Voters in Brazil will elect the country’s president, vice president, and members of its National Congress for the first time since former President Jair Bolsonaro attempted a military coup in 2022. Bolsonaro is under house arrest for his role in the attempted autogolpe, so he can’t run; instead, his son Flávio Bolsonaro is standing. The incumbent President Lula da Silva leads in the polls. Under Lula, Brazil has pledged to cut its greenhouse gas emissions by roughly two-thirds below their all-time high by 2035.
November 3, 2026
On the first Tuesday in November, Americans will vote for the full membership of the House of Representatives as well as one-third of the Senate. Democrats are expected to retake the House — it would, at this point, be a shock if they didn’t — but the president’s polling has become so dire that they’re hoping to beat the odds and take the upper chamber, too. If Democrats succeed in winning Congress outright, expect the second half of President Trump’s term to look quite different, with liberal lawmakers running aggressive oversight campaigns in the run-up to the 2028 presidential election. Interior Secretary Doug Burgum’s plan to overhaul the National Parks Service, for instance, seems like just the kind of effort that could falter in a more scrutinized environment; the Trump administration’s extrajudicial war on wind will also likely face more oversight than it has so far. Trump would also presumably have a much harder time making judicial and Executive Branch appointments.
Even though Election Day isn’t until November, early voting starts in less than a month in some states. Expect to hear a lot more about data centers and electricity bills between now and then. Some state-level races — particularly those in Michigan, Georgia, and Pennsylvania — could also shape the field for the upcoming 2028 presidential election. (Whether Senator Jon Ossoff of Georgia runs for president, for instance, will depend heavily on who wins that state’s governor’s race — and could appoint his successor.)
November 9 to November 20, 2026
The UN’s annual climate conference will be in Antalya, Turkey, this year and begin just a few days after the U.S. midterms. This is going to be a weird summit: Turkey is hosting the physical meeting, but Australia is nominally the “political” host. The conference is supposed to focus on clean energy, zeroing waste, and methane reduction. This will be the 31st meeting of the Conference of the Parties to the UN Framework Convention on Climate Change, and it may offer a look at what a post-Trump, post-1.5 degree Celsius UN meeting could look like.
The industry has gotten excited before, to no avail. Will it stick this time?
Over a decade ago, when the global price of silicon-based photovoltaic modules was roughly five times what it is today, the solar industry and media were already hyping up the next big thing: perovskites, a class of materials defined by their specific cube-like crystal structure. The technology promised to boost photovoltaic efficiency while driving down costs, and the industry was atwitter.
“All the cool solar-cell scientists are working on perovskites photovoltaics,” IEEE Spectrum proclaimed in a 2014 article. In the same piece, Oxford Photovoltaics predicted that it would have commercially available cells within four years. The Wall Street Journal profiled the tech that same year, and in 2015, The Guardian declared that perovskites could be “game changing.” The excitement centered around the potential for higher output at lower costs: Perovskite cells were seeing rapid efficiency gains, could be made from cheap materials, and were remarkably thin and lightweight. When the question of durability came up, it was often as an afterthought. But that has turned out to be the technology’s biggest obstacle.
“What the industry came to understand very quickly is that, yes, you could see higher efficiency, but that material is going to degrade pretty quickly,” Laureen Sanderson, chief communication officer at the perovskite startup Cubic PV, told me. “A lot of the efficiency records that you were seeing were records that were achieved on very small scale devices in a laboratory environment, potentially measured in the dark.” Not ideal for a technology designed to soak up the sun on a large scale.
It’s true that perovskite cells tend to break down rapidly on contact with moisture, heat, and light, a problem scientists have been slowly chipping away at in the lab. That fragility largely arises because perovskites are made of electrically charged ions held together mostly by the attraction between positive and negative charges, much like magnets snapping together. That’s an intrinsically looser structure than the covalent bonds in silicon, which fuse the atoms together via shared electrons. As a result, the ions in perovskites migrate when exposed to the elements, accumulating in places where they react with surrounding materials to form unwanted byproducts that gradually break down the cell’s structure.
But while durability has been its fatal flaw, efficiency is perovskite’s superpower. Silicon’s efficiency tops out at 29.4%, a fundamental physics limitation that no amount of engineering can overcome. But because perovskites can be tuned to absorb different wavelengths of light beyond what silicon can capture, stacking a thin perovskite cell atop a conventional silicon cell lets the combined device make use of more sunlight than either material could alone. In July, one of these silicon-perovskite tandem cells — the industry’s dominant architecture — set a new 35.5% efficiency record.
So while this new tech still doesn’t match the stability of conventional panels, it’s getting much better. Tandem cells hold up increasingly well when exposed to heat, light, and moisture in the lab, and early outdoor trials are starting to produce promising real-world performance data. With headlines about perovskites starting to roll in once more, scientists say there’s good reason to believe that, this time around, the hype might actually be justified.
“Over the better part of a decade, there’s been lots of, for want of a better word, device engineering to engineer the material to just be much more stable,” Sam Stranks, an energy materials professor at the University of Cambridge and co-founder of perovskite startup Swift Solar, told me. That includes swapping out an unstable chemical building block in perovskites called methylammonium with a more stable one called formamidinium, improving the connection point that binds the perovskite layer to the electrode layer, and improving the packaging of perovskite cells to seal them off from air and moisture.
“There’s still work to be done to really get it to the point where you could put it up on a rooftop for 25 years and you know it will last. But the trajectory is very promising,” Stranks said.
Scientists have managed to extend perovskite durability from mere hours to the point where cells and modules are now passing industry-standard tests that suggest they could survive outdoors for five to 10 years. That’s still a ways away from the standard 25-year warranties for silicon solar panels, which typically guarantee that a module will retain 85% to 90% of its original output by year 25. And because these latest perovskites simply haven’t been around that long, scientists have yet to test these more ambitious durability claims in the real world.
Industry experts say there’s no reason continued incremental improvements can’t get perovskites to that 25-year standard relatively soon, however. “If you look at silicon, it’s been 70 years of trial and error,” Scott Wharton, CEO of perovskite startup Tandem PV, told me. “Seventy years of constant tweaking and improvement, whereas perovskites have only had about 12.”
Wharton said that Tandem’s testing indicates its panels will degrade at a rate of less than 1% per year. Furthermore, he predicts perovskites will become the dominant solar technology by 2033, a more ambitious timeline than others in the industry typically project. But as he sees it, seven years is roughly enough time to build and deploy two generations of perovskite factories — the kind of iterative ramp-up he says new technologies typically need to achieve market dominance.
The economics just make sense, he told me. Because perovskites are more efficient, they will produce more power per unit — which means less land, hardware, wiring, and labor needed to achieve the same total energy output, driving down costs at every step of the process. Why wouldn’t everyone jump onboard immediately? “All of our customers have said that once we’ve proven it out, they’re going to move,” Wharton told me. “They’re going to move 100% to tandems because of the power of the efficiency gains.”
Others are somewhat more measured regarding how long this may take. Stranks predicted it would be about five years before perovskites with multi-decade warranties even begin hitting the market, while Sanderson estimated they’ll gain real commercial traction by 2029, with perovskites making up a “significant portion of the market” throughout the 2030s.
While the date of that tipping point remains up for debate, the industry appears to have largely settled the question of materials. At least for now, the preferred configuration is to pair a lead-based perovskite cell with silicon rather than build an all-perovskite cell, which would likely face even greater durability challenges. That’s because such a cell would also need a tin-based perovskite layer to capture lower-energy light like silicon does, but tin degrades even faster than lead. In other words, it’s easier to keep silicon — a proven, durable material — in the mix by building so-called “tandem cells” for the foreseeable future.
But there’s still plenty that remains unknown. Every startup’s exact chemistry is proprietary, and there’s no clearly dominant formula yet. There’s also no industry consensus on the architecture best poised to address perovskite’s stability challenge, either, with leading players typically taking one of two different approaches.
Stranks’ Swift Solar team is pursuing what’s known as a “two-terminal” tandem architecture, in which a manufacturer builds the perovskite layer directly on top of the silicon layer, with the two cells functioning as a single unit. That’s opposed to a “four-terminal” design, where companies build two independent perovskite and silicon cells and then mechanically stack them on top of each other rather than fusing them together.
Two-terminal is the more widely studied approach, pursued by other industry leaders such as Oxford PV — the same company that once predicted commercialization by 2018 — along with Chinese solar giants LONGi and JinkoSolar. Proponents argue that using fewer material layers means less light lost, which translates into greater efficiency and lower costs. In a blog post last year, Swift Solar’s team also argued that the four-terminal designs rely on laser cutting, which it says can create more entry points for degradation.
Two-terminal isn’t just the leading theoretical contender, it’s the first architecture to officially make it to market. Oxford PV’s finally executed its long-delayed commercial launch in 2024, shipping its modules to an undisclosed U.S. customer for use in a utility-scale solar project. It was the world’s first commercial sale of perovskite panels, which Oxford claimed could produce up to 20% more energy than standard silicon modules.
But newer market entrants such as Cubic PV and Tandem PV are bullish on the four-terminal approach. For one, while two-terminal designs use fewer materials, they are more difficult to manufacture. Building a perovskite layer directly onto silicon’s rough surface is more technically difficult than coating it onto smooth glass, as Cubic and Tandem do. And because four-terminal companies manufacture the perovskite and silicon cells separately, they can swap in whatever silicon cell is cheapest or most efficient at any given moment, rather than being locked into a single supplier’s tech.
That flexibility could prove important as the market moves beyond early adopters. For now, Stranks said, customers buying tandem modules are probably doing so for strategic testing purposes — placing small, one-off orders to trial the tech themselves. An installer today can’t simply go buy perovskites on the open market by consulting a public pricing list or product catalogue the way they can with silicon panels. “But it’s not too far away before that would be the case,” he explained.
For its part, Swift is moving … swiftly, acquiring the manufacturing assets and IP of the bankrupt Swiss silicon cell maker Meyer Burger this spring. The company plans to use those assets first to build a U.S.-based gigawatt-scale silicon cell and module factory to meet demand for domestically manufactured solar cells, eventually adding silicon-perovskite tandem module production to that same facility.
Tandem PV is also pushing ahead with plans to begin selling to customers by the end of this year “in a volume that would be big enough to hit bankability goals,” Wharton told me. It also plans to bring a gigawatt-scale factory online by 2028. The company is targeting the independent power producers who build, own, and operate most utility-scale solar projects today. And like Oxford, Swift, and Cubic, Tandem is focused primarily on the utility-scale solar market — by far the biggest opportunity for perovskite technology.
Cubic scrapped plans in 2024 to build a facility producing silicon wafers — the raw material used to make solar cells — amid collapsing wafer prices globally and surging construction costs domestically. While Sanderson says the company remains interested in building its own factory, it has no timeline for doing so. But in the meantime, it’s also interested in licensing its IP to other perovskite companies.
The outlook for domestic wafer production has improved in recent years, though, after the Biden administration provided stronger financial incentives for producing wafers in the U.S. The Trump administration has kept these in place, though it’s made domestic content requirements stricter and more complex overall.
There’s also another new policy variable in the mix: Section 232 tariffs on cheap silicon wafers from China. Going into effect this December, the tariffs could benefit producers like Swift and Cubic, which plan to manufacture silicon cells domestically, while potentially raising costs for companies like Tandem that hope to simply source the cheapest, most efficient silicon available on the market.
At any rate, perovskites give the U.S. a chance to secure a domestic supply chain for the next wave of solar tech. Because while Chinese perovskite producers are setting efficiency records, Wharton told me that they tend to be quieter on the question of durability. That could easily give a Western producer with a credible, multi-decade warranty the opportunity to jump to the front of the pack.
And that may happen sooner than you’d expect. “This always follows the same pattern,” Wharton said of technology breakthroughs generally. “You have a bunch of early entrepreneurs who overhype things, and then everybody goes, Yeah, that was a bunch of BS. And then it actually gets real, and then people go, It’s real, but it’s going to take forever. But then it doesn’t take forever because economics always wins.”