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Why isn’t rooftop solar cheaper in America? In Australia in 2024, a standard rooftop system can cost as little as 90 cents per watt. In the U.S., a similar system might go for $4 per watt. If America could come even close to Australia’s rooftop solar prices, then we would be able to decarbonize the power system much faster than we are now.
Mary Powell has the answers. She is the chief executive officer of Sunrun, a $2.6 billion company that is the country’s largest rooftop solar and battery installer. Sunrun has set up or managed more than 900,000 rooftop systems across the U.S. Powell previously led Green Mountain Power, Vermont’s largest investor-owned power company.
On this week’s episode of Shift Key — a continuation, of sorts, to one of our most popular early episodes — Rob and Jesse talk about how the rooftop solar business works and what’s driving America’s higher costs. Shift Key is hosted by Robinson Meyer, the founding executive editor of Heatmap, and Jesse Jenkins, a professor of energy systems engineering at Princeton University.
Subscribe to “Shift Key” and find this episode on Apple Podcasts, Spotify, Amazon, or wherever you get your podcasts.
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Here is an excerpt from our conversation:
Jesse Jenkins: And so, just some stats to start off the conversation. The latest quarterly solar update from the Department of Energy notes that the average cost of a 2 to 10 kilowatt residential rooftop system in the U.S. is roughly $4 per watt, DC, installed. That’s the full installed system costs, not just the modules.
I just looked up solarchoice.net.au, the Australian site that tracks bids and costs in Australia, which has one of the most vibrant rooftop solar industries in the country. There, you can now install a rooftop solar system in Sydney for just under $1 U.S. per watt, which is quite remarkable — you know, dramatically cheaper than it was a few years ago, but also dramatically cheaper than the U.S residential solar market, by a factor of four.
And so obviously, if we could knock the cost of rooftop solar in the U.S. down by another 75%, it would be an incredible value proposition all over the country. So, how do we get there, Mary? What explains why solar in the U.S., rooftop solar, is much more expensive than it is in places like Australia — I should say, it’s not just Australia. It’s also, you know, the U.K. and Germany and Belgium and other places. Why is it so much more expensive here now than it is in these other countries? And how do we drive down the cost of residential solar installations in the U.S. so that we can unlock that potential here, too?
Mary Powell: Yeah, for sure. I mean, that is so exciting when you think about it, Jesse. What gets me so excited when you say that is I think, ‘Oh my gosh, we are selling all across America now with savings against what people are paying for utility power.’ So customers — even at our current costs. So back to your question on how I see the future, just think about how powerful that will be as we continue to innovate and figure out ways to drive down the cost.
Now, that said, the biggest driver of the cost difference is the way the American energy system is built. And not just that, but we have 40,000 AHJs in the United States that each have their own distinct solar process and rules. And in Australia they have fewer than 600.
Robinson Meyer: And those are like cities?
Powell: It’s housing jurisdictions. It’s like — let me give you an example. In DuPage County, Illinois, we have to have a full time employee pull permits all day. Only one permit at a time.
You know, the other big thing in the U.S. is our whole energy system, as we know, it is very much driven by state and regional rules. Like rules of the road, a lot of regulatory differences from one jurisdiction to another, a lot of massive differences from one utility to another. So, you know, interconnection for residential is still costly, time consuming, and is even prohibited in some areas. Interconnection fees for home solar systems from utilities range from $100 to $10,000. So, one of the bright spots is the work that Sunrun was involved in, a lot of players were involved in, and that Secretary Jennifer Granholm is really focused on, which is SolarAPP+. So, that is one way to drive down the cost, Jesse.
Back to the difference: So really, I would say, the biggest difference is bureaucracy. When you talk about Australia and you talk about the U.S., that’s the biggest difference.
This episode of Shift Key is sponsored by…
Watershed's climate data engine helps companies measure and reduce their emissions, turning the data they already have into an audit-ready carbon footprint backed by the latest climate science. Get the sustainability data you need in weeks, not months. Learn more at watershed.com.
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Music for Shift Key is by Adam Kromelow.
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Economist Philippe Aghion views carbon taxes as a tool to decarbonize, but not a solution in themselves.
Philippe Aghion — one of three Nobel laureates in economics announced Monday — is a theorist of innovation. Specifically, his work concerns “creative destruction,” the process by which technological innovation spreads throughout the economy as new businesses replace old ones, sparking economic growth.
If that reminds you of the energy transition, i.e. the process by which cleaner fuels and new, more efficient ways of generating energy replace fossil fuel combustion, well, you’re not alone.
“I think innovation is the best hope for climate change,” Aghion said in a 2023 interview with VoxTalks Economics. “Of course, we need to innovate in our day to day behavior, but we’ll fight climate change because we will find new sources of energy that are cleaner than coal or gas, and because we will also find ways to produce with energy-saving devices.”
Along with Brown University economist Peter Howitt, Aghion developed mathematical models to describe how creative destruction works, building on foundational work by the Austrian economist Joseph Schumpeter. Along the way, Aghion also worked with 2024 Nobel laureate Daron Acemoglu, who won his prize for describing the institutions that best foster economic growth.
Aghion and Acemoglu have tangled with fellow laureate William Nordhaus, whose models of how the harms of climate change slow down economic growth practically invented the field of climate economics. In Nordhaus’ framing, climate change is the ultimate externality — that is, an economic factor not reflected in the market. The most efficient way to solve climate change, then, is to price in the externality by putting a tax on carbon emissions. Once the price of highly emitting goods reflects the true cost of producing them, the market will naturally favor lower-emitting goods.
Aghion instead sees carbon prices as another way to spur climate-friendly innovation throughout the economy.
In a 2014 paper written with Cameron Hepburn, Alexander Teytelboym, and Dimitri Zenghelis, Aghion argued that “product and process innovation” will ultimately drive decarbonization. Previous approaches to climate economics, Aghion wrote, use inadequate models for the effects of innovation, and so “significantly bias the assessment of the cost of future low-carbon technologies” to be higher than they are in reality.
To be clear, Aghion isn’t against a carbon tax. “A carbon tax or carbon price is a tool to redirect natural charge but it’s not the only tool,” Aghion said during the 2023 interview. “You need other tools, as well,” including “subsidies to green innovation, and more generally green industrial policy.” The point is less to discourage emitters and more to encourage the producers of non-emitting technologies.
Aghion argues that climate policy needs to hit hard and hit quickly, precisely to induce the kind of competitive innovation that he thinks drives economic growth. “If you wait longer, firms will be even better at dirty technologies, and it will take longer before their skills on clean technologies catch up with their skills on dirty technologies, and so you need to act promptly,” he said in 2023.
In a 2012 paper on the auto industry written with Antoine Dechezleprêtre, David Hemous Ralf Martin, and John Van Reenen, Aghion tracks patents in the auto industry and finds that “higher fuel prices induce firms to redirect technical change towards clean innovation and away from dirty innovation.”
He also finds that the nature of the firms matters. Companies that have a background in green technology innovate more in green technology, while companies that specialize in carbon-emitting or “dirty” technologies are more likely to find better ways to emit carbon. You’d expect Porsche or Ferrari to come up with a better internal combustion engine than Tesla, for instance, but for Tesla to invest more in pushing the capabilities of electric drivetrains.
Tesla is in many ways the ideal example of this kind of policy mix working. The company has benefited both from federal and state taxes on gasoline (as well as California’s unique emissions rules), which suppress demand for fossil fuels, and from subsidies and other financial support, which helped it reach economies of scale and performance parity with internal combustion vehicles more quickly.
While theoretically every auto company had the same incentives in both California and the nation as a whole to develop electric vehicles, Tesla made up the bulk of the entire market for years as it never had to split its focus between a legacy internal combustion business and a battery electric business.
Aghion’s work supports this kind of “belt-and-suspenders” approach to climate policy, where fossil fuel emissions are made more expensive and subsidies are provided to advance green innovation.
This may sound pretty familiar. While America’s signature climate law, the Inflation Reduction Act, eschewed carbon taxes in favor of incentives and subsidies, the overall policy mix pursued by the Biden administration — including a fee on methane emissions, regulations on tailpipe and power plant emissions, and increased fuel economy standards — approximated this mix.
Aghion clearly recognized the IRA as a real life version of his ideas. When asked in 2023 about the kind of industrial policy he envisioned, he said, “The Americans are doing it now with the IRA.”
This kind of policy mix wasn’t just optimal policy economically, but also necessary politically.
Pointing to France’s experience with fuel taxes, which led to country-wide protests beginning in 2018, he cautioned that if policy makes dirty fuels more expensive without making clean technology technology cheaper, “then people riot.”
Of course, the IRA and other U.S. climate policies have not been as politically durable as their supporters hoped for. This is despite the fact that, alongside trying to boost green businesses, recent attempts at industrial policy explicitly tried to support “dirty” business, as well, whether by subsidizing older auto companies’ investments in electric vehicles or by supporting carbon capture and hydrogen investments by big oil companies.
But the power of dirty business remained immense — and opposed to climate policy.
The oil and gas industry were some of the biggest supporters of President Trump’s reelection campaign. Since he took office, one of their own — former fracking executive Chris Wright — has overseen the dismantling of much of the Energy Department’s investments in clean energy.
The basic calculus of Aghion’s approach may very well persist as rich countries struggle with growth and the harms attributed to climate change continue to add up.
“I think now we made progress on the idea that innovation is a big part of the solution and … that carbon price is not enough,” he said. “You need smart industrial policy aimed at green innovation. That’s the idea.”
On Corpus Christi’s drought, China’s Scottish factory, and no more ships to give
Current conditions: Texas declared a wildfire disaster in 179 counties as hot, dry, windy weather puts more than half the state at risk • Floods caused by torrential rain from Tropical Storm Raymond and the remnants of Hurricane Priscilla killed at least 41 people in Mexico over the weekend • A heat wave in Central Asia is spiking temperatures as high as 95 degrees Fahrenheit.
Utah Governor Spencer Cox.Kevin Dietsch/Getty Images
Republicans are growing frustrated with President Donald Trump’s rollbacks of policies to support solar energy, the cheapest and fastest-growing source of electricity at a moment when power prices are soaring nationwide. In Georgia, voters who backed the president say the repeal of programs that offered free panels to low-income Americans is making them second-guess their ballots. One of those voters, 39-year-old Jennifer McCoy told The New York Times, “I like a lot of Trump’s outlooks on things, but there are some things, like the solar panels, that I don’t like, now that I know.”
Utah Governor Spencer Cox, meanwhile, went on a tear on X over the Bureau of Land Management’s quashing of the nation’s largest solar project, the 6.2-gigawatt Esmeralda 7 in Nevada. In a post that linked to the scoop Heatmap’s Jael Holzman published last week on the cancellation, Cox said, “This is how we lose the AI/energy arms race with China.” While he noted that “intermittent sources have been overvalued in the past (and offshore wind is a disaster and should be discontinued), the incredible leaps in battery technology completely change the value proposition of solar in the right places.” He went on to re-post messages from three think tank researchers criticizing the move and warnings about the energy needs of data centers.
Corpus Christi is the main water provider for South Texas, a region that has drawn the likes of Tesla, Exxon Mobil, fuel refineries, plastic producers, and lithium processors with what The Wall Street Journal called “the promise of land, cheap energy and, perhaps most critically, abundant water.” But a crippling drought is depleting the region’s reservoirs, and the city may fail to meet the area’s water demand in as little as 18 months. “Cue the panic,” the newspaper wrote. Industrial plants are bracing for rate hikes. “The water situation in South Texas is about as dire as I’ve ever seen it,” said Mike Howard, chief executive of Howard Energy Partners, a private energy company that owns several facilities in Corpus Christi. “It has all the energy in the world, and it doesn’t have water.”
China last week ratcheted up restrictions on exports of rare earths, including for electric vehicle batteries and semiconductors, kicking off another round of the trade war with the United States. But in Scotland, one of China’s biggest wind turbine manufacturers is investing more than $2 billion in building a new factory. Guangdong-based Ming Yang announced plans for its new plant to churn out parts for offshore turbines on Friday, though the company said the move was “subject to final approvals from the U.K. government,” the Financial Times reported.
In the U.S., meanwhile, the Trump administration’s crackdown on offshore wind is so severe the oil industry is stepping in to complain, warning that it’s setting a dangerous precedent for other energy sectors, as I reported in this newsletter last week. But private actors are, at least, responding to the Trump administration’s push to re-shore critical industries to the U.S. On Monday morning, JPMorgan Chase announced plans to invest $10 billion into mineral production and infrastructure for artificial intelligence.
Equinor’s 810-megawatt Empire Wind project off the coast of New York’s Long Island has faced real challenges, with the Trump administration halting construction in April before allowing it to resume in May. The latest hurdle? The developers can’t get hold of the specially-made vessel for installing wind turbines it was counting on having by next year. As Canary Media’s Clare Fieseler wrote on Friday, two shipbuilding companies broke into a public skirmish, with one unexpectedly canceling a contract and the other threatening legal action over the construction of the specialized ship. The vessel, which is more than 98% complete, is anchored in Singapore, its fate now uncertain. “We have been informed by Maersk of an issue concerning its contract with Seatrium related to the wind turbine installation vessel originally contracted by Empire Offshore Wind LLC for use in 2026,” an Equinor spokesperson told Fieseler. “We are currently assessing the implications of this issue and evaluating available options.”
The episode shows how the Trump administration’s “total war on wind power,” as Jael once put it, makes companies more vulnerable to other setbacks. The White House tasked a half-dozen federal agencies, as I previously wrote, with trying to block construction of offshore turbines. But the general lack of ships capable of carrying giant turbines was a problem even before Trump returned to office.
California lawmakers last week passed Senate Bill 655, a first-in-the-nation framework to set maximum standards for safe indoor temperatures in residential housing. The bill requires state agencies to achieve the standard as heat deaths surge across the country. While the state has long required homes to maintain a minimum indoor air temperature of 68 degrees Fahrenheit, there was no equivalent standard for heat. “SB 655 responds to the public health emergency of California’s deadly heat waves,” Senator Henry Stern, the bill’s lead author, said in a statement. “This bill proactively requires the state to include safe residential indoor temperatures in its policies and programs so that Californians, especially renters and low-income households who are most at risk, have life-saving cooling.”
It’s part of a bigger wave of state legislation on climate and energy that California just passed, as Heatmap’s Emily Pontecorvo outlined recently. Among them: Families who lose everything in future wildfires will now be able to collect the bulk of their insurance payout without having to catalog every item burned in the blaze under new legislation Governor Gavin Newsom signed Friday. Starting in 2026, as The New York Times reported, insurers must pay at least 60% of a homeowner’s personal-property coverage — up to $350,000 — without requiring a detailed inventory of everything lost. That’s double the 30% of the dwelling’s value that insurers were required to pay out in advance, with a payout capped at $250,000.
As the Trump administration is gutting funding for America's polar research, the British are stepping in. The British Antarctic Survey’s RRS Sir David Attenborough, a state-of-the-art ship named after the famed naturalist, will bolster research on everything from “hunting underwater tsunamis” to tracking glacier melt and whale populations. “The saying goes 'what happens in Antarctica doesn't stay in Antarctica,’” BAS oceanographer Peter Davis told reporters during a tour of the vessel as it prepared to depart Harwich, eastern England, last week.
The administration seems to be pursuing a “some of the above” strategy with little to no internal logic.
The Department of Energy justified terminating hundreds of congressionally-mandated grants issued by the Biden administration for clean energy projects last week (including for a backup battery at a children’s hospital) by arguing that they were bad investments for the American people.
“Following a thorough, individualized financial review, DOE determined that these projects did not adequately advance the nation’s energy needs, were not economically viable, and would not provide a positive return on investment of taxpayer dollars,” the agency’s press release said.
It’s puzzling, then, that the Trump administration is pouring vast government resources into saving aging coal plants and expediting advanced nuclear projects — two sources of energy that are famously financial black holes.
The Energy Department announced it would invest $625 million to “reinvigorate and expand America’s coal industry” in late September. Earlier this year, the agency also made $900 million available to “unlock commercial deployment of American-made small modular reactors.”
It’s hard to imagine what economic yardsticks would warrant funding to keep coal plants open. The cost of operating a coal plant in the U.S. has increased by nearly 30% since 2021 — faster than inflation — according to research by Energy Innovation. Driving that increase is the cost of coal itself, as well as the fact that the nation’s coal plants are simply getting very old and more expensive to maintain. “You can put all the money you want into a clunker, but at the end of the day, it’s really old, and it’s just going to keep getting more expensive over time, even if you have a short term fix,” Michelle Solomon, a program manager at Energy Innovation who authored the research, told me.
Keeping these plants online — even if they only operate some of the time— inevitably raises electricity bills. That’s because in many of the country’s electricity markets, the cost of power on any given day is determined by the most expensive plant running. On a hot summer day when everyone’s air conditioners are working hard and the grid operator has to tell a coal plant to switch on to meet demand, every electron delivered in the region will suddenly cost the same as coal, even if it was generated essentially for free by the sun or wind.
The Trump administration has also based its support for coal plants on the idea that they are needed for reliability. In theory, coal generation should be available around the clock. But in reality, the plants aren’t necessarily up to the task — and not just because they’re old. Sandy Creek in Texas, which began operating in 2013 and is the newest coal plant in the country, experienced a major failure this past April and is now expected to stay offline until 2027, according to the region’s grid operator. In a report last year, the North American Electric Reliability Corporation warned that outage rates for coal plants are increasing. This is in part due to wear and tear from the way these plants cycle on and off to accommodate renewable energy sources, the report said, but it’s also due to reduced maintenance as plant operators plan to retire the facilities.
“You can do the deferred maintenance. It might keep the plant operating for a bit longer, but at the end of the day, it’s still not going to be the most efficient source of energy, or the cheapest source of energy,” Solomon said.
The contradictions snowball from there. On September 30, the DOE opened a $525 million funding opportunity for coal plants titled “Restoring Reliability: Coal Recommissioning and Modernization,” inviting coal-fired power plants that are scheduled for retirement before 2032 or in rural areas to apply for grants that will help keep them open. The grant paperwork states that grid capacity challenges “are especially acute in regions with constrained transmission and sustained load growth.” Two days later, however, as part of the agency’s mass termination of grants, it canceled more than $1.3 billion in awards from the Grid Deployment Office to upgrade and install new transmission lines to ease those constraints.
The new funding opportunity may ultimately just shuffle awards around from one coal plant to another, or put previously-awarded projects through the time-and-money-intensive process of reapplying for the same funding under a new name. Up to $350 million of the total will go to as many as five coal plants, with initial funding to restart closed plants or to modernize old ones, and later phases designated for carbon capture, utilization, and storage retrofits. The agency said it will use “unobligated” money from three programs that were part of the 2021 Infrastructure Investment and Jobs Act: the Carbon Capture Demonstration Projects Program, the Carbon Capture Large-Scale Pilot Projects, and the Energy Improvements in Rural or Remote Areas Program.
In a seeming act of cognitive dissonance, however, the agency has canceled awards for two coal-fired power plants that the Biden administration made under those same programs. One, a $6.5 million grant to Navajo Transitional Energy Company, a tribal-owned entity that owns a stake in New Mexico’s Four Corners Generating Station, would have funded a study to determine whether adding carbon capture and storage to the plant was economically viable. The other, a $50 million grant to TDA Research that would have helped the company validate its CCS technology at Dry Fork Station, a coal plant in Wyoming, was terminated in May.
Two more may be out the window. A new internal agency list of grants labeled “terminate” that circulated this week included an $8 million grant for the utility Duke Energy to evaluate the feasibility of capturing carbon from its Edwardsport plant in Indiana, and $350 million for Project Tundra, a carbon capture demonstration project at the Milton R. Young Station in North Dakota.
“It’s not internally consistent,” Jack Andreason Cavanaugh, a global fellow at the Columbia University’s Carbon Management Research Initiative, told me. “You’re canceling coal grants, but then you’re giving $630 million to keep them open. You’re also investing a ton of time and money into nuclear — which is great, to be clear — but these small modular reactors haven’t been deployed in the United States, and part of the reason is that they’re currently not economically viable.”
The closest any company has come thus far to deploying a small modular reactor in the U.S. is NuScale, a company that planned to build its first-of-a-kind reactors in Idaho and had secured agreements to sell the power to a group of public utilities in Utah. But between 2015, when it was first proposed, and late 2023, when it died, the project’s budget tripled from $3 billion to more than $9 billion, while its scale was reduced from 600 megawatts to 462 megawatts. Not all of that was inevitable — costs rose dramatically in the final few years due to inflation. The reason NuScale ultimately pulled out of the project is that the cost of electricity it generated was going to be too high for the market to bear.
It’s unclear how heavily the DOE will weigh project financials in the application process for the $900 million for nuclear reactors. In its funding announcement, it specified that the awards would be made “solely based on technical merit.” The agency’s official solicitation paperwork, however, names “financial viability” as one of the key review criteria. Regardless, the Trump administration appears to recognize the value in funding first-of-a-kind, risky technologies when it comes to nuclear, but is not applying the same standards to direct air capture or hydrogen plants.
I asked the Department of Energy to share the criteria it used in the project review process to determine economic viability. In response, spokesperson Ben Dietderich encouraged me to read Wright’s memorandum describing the review process from May. The memo outlines what types of documentation the agency will evaluate to reach a decision, but not the criteria for making that decision.
Solomon agreed that advanced nuclear might one day meet the grid’s growing power needs, but not anytime soon. “Hopefully in the long term, this technology does become a part of our electricity system. But certainly relying on it in the short term has real risks to electricity costs,” she said. “And also reliability, in the sense that the projects might not materialize.”