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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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Europe’s heat wave has finally ended — and good riddance. The continent recorded at least 1,300 excess deaths over the past week, according to the World Health Organization. Mortuaries in Paris and other cities were overwhelmed.
North America will now get its turn with summertime heat: At the end of this week, New York, Philadelphia, and other cities down the East Coast — including several where World Cup knock-out games will be played — could see their hottest temperatures since 2012.
As I wrote last week, these bouts of extreme heat are caused by climate change. Severe and record-breaking heat waves are one of anthropogenic global warming’s clearest and most indisputable symptoms.
But as I also wrote last week, Europe and North America have very different ways of dealing with extreme heat. Most Americans have air conditioners, but they remain rare in Europe — and especially in northwestern Europe, including France, Germany, and the United Kingdom.
Since last week, I have read countless explanations about why Europeans don’t have air conditioning at the same rates as Americans — or even Canadians. Perhaps Americans and Europeans have a different relationship to suffering, goes one theory, or maybe the European left has managed to politicize air conditioning in a way that the American left has never tried to do. The cultural divide here is more real than I once would have thought: In Paris, the deputy mayor chided Americans for even asking about Europe’s AC use; she argued air conditioning “contributes and aggravates” to air pollution and climate change. In Florida, meanwhile, we name elementary schools after the inventor of mechanical refrigeration.
Throughout all of this, I’ve assumed that Europeans would purchase air conditioning as the warming climate demands it. Much like the Pacific Northwest, where AC adoption lagged the rest of the United States for decades, much of Western Europe used to enjoy a climate where AC was unnecessary. That changed in Oregon, Washington, and British Columbia after the 2021 heat dome. Now that summertime highs are rising in Europe, too, it seemed obvious that people would go out and buy window unit air conditioners — and where they can’t buy them because of local laws, they’ll push for reform.
It had not occurred to me, though, that a simpler obstacle might be blocking Europe’s adoption of AC. Jonas Nahm, a professor of industrial strategy at the Johns Hopkins School of Advanced International Studies, wrote in with a question: What if it’s the windows?
Do you know about Europe’s superior windows? Unlike the United States, where most of our windows hang on a sash and open vertically, the dominant form of window in Germany, Austria, France, Italy, and the rest of the Blue Banana are tilt-turn windows. This distinctive form of fenestration has a dual-action hinge, meaning it can tilt, opening at the top to let in light or air; and turn, swinging fully open on its hinges.
Tilt-turn windows are superior in most respects to our American sash windows or casements. Because they close more securely, they provide better protection against the elements; because you can swing them into a room and access both sides of a pane, they are easier to clean; and because you can tilt them from the bottom and crack them open at the top, they can ventilate a room without creating a draft. They are also ubiquitous in western Europe. Asked once what Germany meant to her, Germany’s former Chancellor Angela Merkel replied: “I think of well-sealed windows. No other country can make such well-sealed and nice windows.”
They are superior in all respects, I would say — except for one. When Americans in older buildings want to get an air conditioner, we go and buy a window unit, then we slide up the sash window and install it. But tilt-turn windows are not so accommodating. Those who have them must instead go and buy a portable AC unit that sits entirely inside a room, snake its hose out the top of the window, and then either purchase a fabric barrier or jerry-rig towels to seal off the crevices.
If you can’t buy a window unit, in other words, then your air conditioning options narrow. You either have to install an unsightly portable AC unit. Or you have to retrofit your entire home and install mini-splits — a far more expensive renovation that may not even be possible in historic or rental buildings.
Can windows alone explain Europe’s differing approach to air conditioning? It certainly explains a gap I’ve noticed in the discourse, where some Europeans seem to see air conditioning as an exorbitant luxury and Americans see it as, well, just another $250 purchase. It matters, too, that most Europeans heat their homes with radiators, meaning there is no forced-air ductwork system that a central air system can piggyback on. (Of course, my 100-year-old apartment building has radiators, too — but we have sash windows, and therefore window units.)
As it happens, I’ve lived in a home in the United States that had tilt-turn windows. An old German landlord of mine installed them in about half the house. We had window units too, but we stuck them in the few rooms that still had sash windows.
But of course, maybe what you don't have always seems more exotic to you. Not so long ago, I found myself in a smoky Berlin bar talking with a German about how much I liked and respected their windows. My companion was confused and asked me what windows were like in America, and I pantomimed opening a sash window and sticking my head out the bottom.
He was thrilled. Wait, he replied, just like in the movies?
I promise tomorrow's newsletter will not be about windows or air conditioning.
Monday’s Supreme Court decision will give Trump sweeping powers over the agency he already effectively controls.
The Supreme Court on Monday morning effectively OK-ed the firing of commissioners at independent agencies with no showing of cause, overturning a 90-plus-year-old precedent and granting the president seemingly vast powers to reshape the federal regulatory state. That likely includes agencies crucial to energy planning and governance, including the Federal Energy Regulatory Commission and the Nuclear Regulatory Commission (though not, notably, the Federal Reserve Board of Governors).
Harvard Law School professor Ari Peskoe argued in an amicus brief for the case alongside a bipartisan gaggle of 11 former FERC commissioners that deciding in the president’s favor on this case “would bulldoze the structural supports that Congress built into ratemaking commissions to protect its price-setting power from abuse,” protections that “foster regulatory stability for industries investing in essential infrastructure.”
So what’s left of that stability following the Supreme Court’s decision? “It’s been 3+ hours and the President has yet to fire a FERC Commissioner. So no immediate effect,” Peskoe told me in an email.
The case stemmed from Trump’s firing of Rebecca Slaughter, a member of the Federal Trade Commission, because her presence on the Commission would, he said, be “inconsistent with my Administration’s priorities.” Slaughter sued to be reinstated under a precedent established in the 1935 case Humphrey’s Executor v. the United States, in which the Supreme Court ruled that the Constitution did not give the president “illimitable power of removal” over government officials. On Monday, the court disagreed, deciding instead that the President should have wide discretion over the composition of agencies like the FTC, which “unquestionably exercises executive power and must therefore be controlled by the Chief Executive,” Chief Justice John Roberts wrote in his opinion for the majority.
In her dissent on the decision, which split 6-3 along the usual partisan lines, Justice Sonia Sotomayor listed FERC and the NRC as among the “dozens of independent commissions are now likely to become purely executive agencies, shifting tremendous power over broad swaths of American life into the President’s hands.”
Agencies like FERC tend not to be as explicitly politicized or partisan as, say, the Environmental Protection Agency, which is led by a single administrator who serves at the pleasure of the president, or the National Labor Relations Board or Federal Election Commission, which oversee areas of law and policy with stark partisan and ideological stakes. This is partly because FERC justifies decisions on electricity and natural gas policy with reference to “technical expertise,” Peskoe’s fellow Harvard Law School professor and former Obama White House official Jody Freeman told me. (If you have any doubt about this, go read through some 1,000-page-plus FERC orders.
FERC also tends to be more collegial than most other independent agencies. Meetings often include encomia to the agency’s chair for being consensus-oriented, and to its staff, who serve commissioners from both parties. Its recent “show cause” orders directing regional electricity markets to prove they’re taking steps to speed up grid interconnection for large new sources of demand garnered a 5-0 majority, with both Democrats on the Commission voting along with their Republican colleagues.
And FERC chairs do occasionally defy the presidents who have appointed them, most notably in Donald Trump’s first term, when then-Chair Neil Chatterjee dismissed Secretary of Energy Rick Perry’s request to support coal and nuclear power plants able to store fuel on site, thus propping up struggling electricity generators.
Interestingly, Chatterjee, who signed the amicus brief to the court, was relatively relaxed about Monday’s decision’s implications for his former agency about. He observed to me in an email, “given that the commission just voted 5-0 on the WH’s biggest priority before FERC I don’t see it being an issue in the near term.”
In other words, FERC and this White House, at least, already see eye to eye.
But that’s no coincidence. Since the beginning of this term, the White House has set out to rein in and control independent agencies, FERC among them. Though Trump initially tapped sitting Republican Commissioner Mark Christie to lead the commission, he ultimately declined to re-nominate Christie for a second five-year term, leading to Christie’s exit from the commission last August.
In his place, the president installed Laura Swett, who has allowed little daylight between the commission’s and the White House’s positions. Both have attempted to keep the focus on balancing the buildout of data centers to serve artificial intelligence while keeping a lid on consumer electricity prices.
While it’s not foreordained that FERC chairs will agree with the presidents that appointed them, even if they’re both members of the same party, Monday’s decision makes disagreement more dangerous for current and future FERC chairs to consider.
“There’s a bigger risk that they’ll have to ultimately yield to political pressure because they’ll have this very overt threat that they’ll be fired,” Freeman told me. “We’re going to see decisions that look more political, that look less expertly driven, and they probably will wax and wane with every new administration, which undermines stability.”
A longtime energy analyst argues that there are no solutions to the hyperscale problem, only tradeoffs.
Sam Altman, Dario Amodei, and Elon Musk need sign-off from fewer than a dozen board members to commit their companies to multibillion-dollar moves. The power plants that supply their data centers need sign-off from 13 states (plus D.C.), thousands of generators, millions of customers, and a federal regulator whose ratemaking standard predates the personal computer in order to build anything new.
Everyone in tech knows about the CEOs of the foundational artificial intelligence labs. Only energy nerds know the names of the people running our grid operators. That anonymity is a feature, not a bug. Grid operators generally think in decades, not years. But right now, they’re telling the U.S. that it has years, not decades, to figure out its own new path forward.
For decades, this process sufficed for energy generators (and regulators) grown accustomed to gradual, predictable load growth. But over the past several years, the scale and speed of increasing energy demand has overwhelmed the supply -side’s ability to respond. The resulting strain on the grid has reverberated through every rung of the supply chain, delaying development timelines, increasing costs, and elevating energy from political conversations to dinner table discussions.
The loudest creaks and groans are coming from PJM Interconnection, North America’s largest grid operator. Residential bills in the PJM service area are climbing at a dizzying pace. Recent capacity auctions have ended with record prices, which PJM’s own market monitor blames on the explosive growth in data center power demand. Pennsylvania Governor Josh Shapiro has attempted to pressure PJM to lower its capacity price cap. Even Secretary of Energy Chris Wright has called on the Federal Energy Regulatory Commission to develop new procedures to help get data centers online faster.
David Mills, PJM’s CEO, published a 70-page report in May acknowledging that current market rules cannot keep pace with AI-driven load growth. And yet he also refused to recommend a path forward, leaving the decision to “state regulators and legislatures, to FERC, to consumers.”
The most essential grid infrastructure, he explained, “is not a price curve or a performance obligation — it is legitimacy.” In other words, what’s broken isn’t a parameter inside the capacity market, but rather the capacity market itself, along with the political conditions under which it operates. PJM calls this the “credibility trap”: high prices accurately signal that new investment is needed, but when those prices become politically untenable, government intervenes and investment stalls.
The fix, Mills writes, “requires structural choices, not just parameter adjustments.”
Mills is speaking to a deeper issue with the grid than its ability to respond to shifting market dynamics, which is that hyperscalers and grid operators are built to solve two different kinds of problems. Hyperscalers solve engineering problems with specifiable objectives, known constraints, verifiable outcomes. Engineering problems reward concentrated authority and unilateral decision-making.
Grid operators, on the other hand, solve coordination problems. The information they rely on to do so is dispersed across millions of stakeholders, continuously revised and often contradictory, and operators’ preferences are not so much known as they are revealed through deliberation. FERC’s standard for wholesale rates is not whether those rates are objectively “correct,” but rather whether the market settled on those rates through fair competition. The process does not just determine the answer, it essentially is the answer.
This construction is the category error driving the current AI-grid collision. The electricity grid is not an engineering problem with coordination problems attached. It is a coordination problem with engineering problems embedded in it. Treat it as the former and you lose all the information that gets generated in the process of market-based price discovery. You also lose all the buy-in that occurs when real people are faced with real trade-offs and have to make hard, binding choices.
Mills did lay out three possible structural paths in his May letter:
These pathways are not equivalent — unlike with an engineering problem, there are no cut-and-dried solutions here. There are only trade-offs and questions about who bears their consequences. Path C is likely the better answer, while Path A is more expedient. The gap between them is the work PJM’s constituents have to manage over the coming years. PJM may choose the wrong path, or arrive at the right one too late.
The alternative is not hypothetical. If hyperscalers aren’t willing to wait for PJM customers to decide which path they want to take (and recent history suggests they are not) they will build behind-the-meter generation, sign bespoke deals with regulated utilities, and restart dormant nuclear plants. America would be left with two grids, one for compute, one for everything else. The first will be reliable and expensive. The second will be cheaper, fragile, and stranded with the costs of the system the first walked away from. The market would lose the dispatch signal, the error-correcting price mechanism, and the legitimacy of the system that has reliably powered the Mid-Atlantic for two decades.
Economist Friedrich Hayek described the limits of humans’ planning capabilities better than anyone in his 1974 Nobel Prize lecture, using the metaphor of the craftsman shaping his handiwork versus the gardener cultivating growth. The craftsman thinks they can make a perfect tool but repeatedly runs up against the boundaries of their own knowledge, whereas the gardener learns to manage new information as it arises, tending not to the product itself but rather to the conditions that produce it.
Hyperscalers are not bad actors. They have legitimate interests and the political capital to help shape the grid’s future. But we should resist the Newtonian urge to meet unexpected, swiftly moving demand with equally swift supply. Markets and physical systems both tend toward equilibrium, but the former finds it through deliberation, not collision. Instead of trying to unilaterally craft a better grid, hyperscalers might find a better path if they work with the practitioners who already know how to garden.