As soon as Julie Bishop opens the gate of her red trailer, a herd of sheep bound out, eagerly inhaling a few blades of grass before scattering to explore their new stomping grounds. The herd of Katahdin sheep arrive every spring to graze on a series of concealed fields owned by Princeton on the other side of Lake Carnegie and by Forrestal campus, where we now stand. This field will host the herd until the end of July, its grasses staying low to the ground as the sheep graze with gusto.
Unlike most sheep, though, Bishop’s will have to be careful not to hit their heads: they share the field with thousands of solar panels, part of Princeton’s expansive solar farm system that generates up to 19% of the University’s power and plays a crucial role in its climate ambitions. These sheep play an important role, too; they keep the grass trimmed so that it doesn’t block light from hitting the panels.
At first glance, Princeton’s solar projects—the first in 2012, the second coming nine years later in 2021—describe an ongoing success story: part of the rise of solar energy as an alternative to fossil fuels. Indeed, even in the mere nine years between Princeton’s two solar expansions, the industry leaped forward in sophistication across manufacturing, installation, and maintenance. But even though solar costs have dropped due to massive economic incentives, the technology has not been fully embedded into society yet. People haven’t quite figured out how to integrate it into the architectural, economic, political and social design frameworks that support conventional energy generation. Companies may be throwing panels on the ground at an increasingly rapid pace, but because solar remains a newcomer and generates electricity in an unfamiliar way, this breakneck expansion may come with potentially damaging consequences for both local communities and the country’s broader climate goals. Over the following pages, I hope to share this story of solar’s successes and the road left ahead of us on the journey to climate safety.
Chapter 1: A First Start
One day early in 2010, Princeton Energy Plant Manager Ted Borer tells his boss, “Three things have changed. We should put our pedal to the floor.”
With these words, Borer kicks off Princeton’s largest foray into solar at the time. Monitoring the solar industry for the previous decade, he observed consistent decreases in the cost of solar power and accelerating (though patchwork) solar installation across the country. Up until this point, both power and installation remained prohibitively expensive: not only were photovoltaic modules costly, but the design of solar’s ‘balance of plant’ (the infrastructure that’s required to support these modules) was still in its infancy.
But the three factors which Borer cites push the University to take the leap. The first: a shocking drop in the price of solar photovoltaic modules, from $4 per watt in 2008 to $2 per watt in 2010, just two years later. Second came favorable incentives from New Jersey’s Solar Renewable Energy Credit (SREC) program, part of a carbon market scheme which had been created five years earlier to support the state’s goal of reaching 50% renewable energy generation by 2030. The final factor behind Borer’s recommendation was the 2009 American Recovery and Reinvestment Act (ARRA), a stimulus bill passed by Congress which sought to repair the country’s economy in the aftermath of the 2008 recession. The Obama administration hoped to jumpstart the solar industry, and so policymakers put roughly $40 billion on the table in investments and tax incentives for private solar companies. Along with hundreds of other institutions throughout the country, Princeton takes the money.
Policymakers designed the ARRA to dispense solar funding as a tax credit. Therefore, as a nonprofit institution that does not pay federal taxes, Princeton can’t claim the ARRA’s financial benefits for itself. To surmount this legal hurdle, the University brings on board the bank Key Government Finance (KGF) to hire a solar company, SunPower, which designs and installs the 5-megawatt (MW) solar array. KGF, a for-profit company, qualified for ARRA tax credits and could thus build the farm for a reduced price and lease it to Princeton for a lower cost. Princeton would lease it from them for the next eight years. “We paid them a lease rate, we took all the risk on whether it produced anything, we took care of the maintenance [and] the insurance,” Borer said.
Princeton agreed to KGF’s lease, and by October of 2012, after months of permitting and then construction, 16,528 brand-new panels began to generate energy. Their 27-acre farm covers land that Princeton had previously used as a waste site for sediment and organic material it had collected after dredging Lake Carnegie in the 1970s. The farm begins to generate around 5.5% of Princeton’s annual electricity demand, and continues to operate to this day.
Chapter 2: Growing Confidence
Solar power experiences its most dramatic advance in the 2010s, between Princeton’s two main solar projects. The economic benefits of solar mount, causing adoption of the technology to skyrocket in the eight years after the 2012 installation. Price, installation, and capacity records are smashed year after year. In 2012, the United States claimed roughly 7,300 MW(DC) of solar capacity (solar panels generate electricity in direct current, DC, but it takes further energy to convert that electricity into usable alternating current, AC). By 2020, that number shoots up thirteenfold, to over 100,000 MW(DC) of solar capacity installed nationwide (in comparison, natural gas boasted 480,000 MW of capacity in the US that year).
Manufacturers, especially in China, contribute to the slashed cost of photovoltaic modules through technological improvements module efficiency And advances in technological and labor efficiency sharply cut the installation price of solar panels, according to Brent Alderfer, an early renewable energy developer, former Commissioner on the Colorado Public Utilities Commission, and Andlinger Center E-ffiliate. The advancements tackle the ‘balance of plant’ costs of each solar facility by improving on all the elements that support the installation of photovoltaic modules. Innovations like standardized wire harnesses, improved panel mounting and racking, and single axis tracking (which allows the panels to follow the sun’s path) all bring down total capital costs per unit of electricity output. These achievements would not have been possible without the sheer number of new solar farms and the economies of scale they created. A decade ago, projects could cost anywhere from four to seven dollars per watt of solar. “Not long ago we were down to close to one dollar a watt,” Alderfer said. Some cost increase has occurred from supply constraints and rising labor costs
Princeton continues to monitor this swelling industry and announces its next slate of 8 solar projects in 2020. Taking advantage of the dramatic reductions in costs over the previous eight years, Princeton could install its newest farms under a Power Purchase Agreement (PPA) with a French solar installation company called EDF Renewables. Princeton gives permission to the company to build solar farms on its property. In return, as Borer explained, the University “guarantee[d] that for 15 years, we’ll buy whatever this stuff produces.”
Using a PPA, Princeton could install a large solar project without undergoing the process of raising upfront capital: capital costs for the arrays are folded into the price Princeton pays to purchase the arrays’ electricity. And the University gains a fixed price of electricity for the duration of its lease, reducing unpredictability. In return, EDF can lock in a steady revenue stream from Princeton, reducing the risk of their project in a volatile energy market driven by fossil fuel prices and accustomed to the way solar generates electricity. Thirteen years from now, Princeton will purchase whatever remains of EDF’s on-site solar equipment and gain full ownership of the farms.
The new expansions add roughly 12 MW of solar capacity to Princeton’s campus, across car parks, rooftops and University-owned fields in West Windsor, past Lake Carnegie. They bring Princeton’s total solar capacity to 16.5 MW—a total which meets approximately 19% of the University’s current electricity demand.
Chapter 3: Enter the Inflation Reduction Act
As 2022 rolls around, Borer looks out on a transformed solar environment. “The financials have changed yet again,” he tells me. It took eight years of continual change in the economic frameworks behind solar for Princeton to move from a lease-then-purchase agreement in 2012 to a PPA model in 2021. But within a year, that model upended once more, changing the pricing scheme behind Princeton’s planned 4-array solar expansion. “And that has a lot to do with the Inflation Reduction Act of 2022,” he said.
“Biden’s Inflation Reduction Act is just unbelievable. Just… blow you away, really amazing,” said Tom Leyden ’77, a solar specialist who started in the industry back in the 1980s. “It’s the first time in a long time that we’ve had industrial policy that makes super good sense for the country.” The Inflation Reduction Act (IRA), passed last October, is currently pouring billions of dollars into clean energy, intensifying the already-growing solar bonanza by catalyzing a new wave of projects. Dubbing the IRA “the most transformational clean energy policy in history,” the Solar Energy Industries Association estimates it will spur an additional 222,000 MW of solar power over the next decade compared with a no-IRA scenario (currently, the United States can claim about 1,140,000 MW of electricity generating capacity).
Importantly, unlike ARRA, the IRA allows nonprofits to receive money directly from the federal government. Princeton, therefore, can reap the full benefits of the IRA themselves when it installs the next batch of solar projects, rather than having to rely on other companies. And it will spend a large enough sum to make Borer pivot from operating Princeton’s next solar project through a PPA to buying, installing, and maintaining it directly through the University. “When I do the math, it sure looks to me like the best thing to do today,” he said.
“Now that we’ve owned and operated [solar] for a while, we have a fairly good idea what [the financial] risks look like,” Borer assured me. “So we’re more comfortable buying outright than having somebody else own and operate and maintain.”
This dramatic financial pivot took place in under two years.
The IRA, however, doesn’t solve everything—especially beyond the Orange Bubble. It aimed to spur the rapid growth of renewable energy by throwing money at companies and institutions that want to install solar, but it didn’t necessarily change a wide array of structural frameworks that continue to hinder solar’s advance.
Chapter 4: Where we’re going
The money needed to develop enough solar to decarbonize the country (more or less) exists. The design principles to support solar’s full integration into the country’s energy, landscape, and social systems don’t—yet. As a result, while Princeton may be able to surmount many of the challenges that solar still poses, due to its large endowment and wealth of experience, many attempts by other institutions elsewhere in the country to install solar will fail unless more is done, and done fast.
“They’re overwhelmed right now”
Let’s start with grid design. Because of the way it has established its physical infrastructure and energy markets, the US energy grid can’t accommodate the flood of renewable projects that developers have built in the past few years—much less the latest round of projects that have begun since the passage of the IRA.
The country’s physical infrastructure which connects energy generators to energy consumers has failed to keep up with renewable energy projects that have already been proposed and even already built. In Southern New Jersey alone, electricity transmission lines have taken on so many generators that they have nearly reached maximum capacity under traditional interconnection rules; if they were to take on much more electricity, they would likely fail. “The circuits arey’re all closed,” Leyden said.
Building a new sprawling network of transmission lines may take years, as utilities are most comfortable with building a few transmission lines only for large, centralized power plants—“an old school mentality,” according to Leyden. The recent wave of small- to medium-size renewable projects (Princeton’s is on the larger end of this scale) breaks from this existing design scheme. And utilities remain notoriously slow to change. In states with deregulated energy markets like New Jersey, utilities pay for transmission line upgrades through a surcharge to their customers. But to do so, they have to gain approval from grid regulators in addition to local permitting before they can perform these upgrades, a painstaking and alarmingly slow process which can cause many renewable project developers to throw in the towel. Furthermore, utilities are often reluctant to connect to other utilities’ jurisdictions for fear of losing control over their local markets.
Adding to America’s transmission woes is a related issue: grid interconnection. While transmission lines take electricity and distribute it across vast distances, interconnection is a (theoretically) more straightforward operation, as it only requires connecting electricity generators to the rest of the grid.
But right now, with companies developing thousands of new solar and wind projects and requesting connection to the grid, the interconnection process is essentially stalled. In fact, PJM, a Regional Transmission Operator that governs the flow of electricity across a wide region spanning from New Jersey to Ohio, paused its review of interconnection requests across its entire territory until 2026 to work on streamlining its review process. Ninety-five percent of these requests, which would add up to 250 GW of new capacity in total, are for renewable projects, with a large share of these being small-scale ‘distributed’ renewables like rooftop solar. “They’re overwhelmed right now: just thousands upon thousands of applications for distributed generation,” Leyden said. “They can’t keep up.” In the meantime, no additional solar farms can link up to the grid.
“Has anyone specified a blueprint for a system with large amounts of wind and solar?”
However, Alderfer, the solar developer and former Colorado Public Utilities Commissioner, believes that transmission and interconnection delays will get solved eventually—the question is at what speed. PJM has succeeded in installing transmission over the last two decades, allocating about $40 billion towards transmission investment. “We built a lot of transmission over the last decade to accommodate new natural gas generation, replacing coal faster than expected,” Alderfer said. “We can do that again to build out solar and wind faster than expected—if economic forces are aligned for solar and wind as they were for gas.”
Alderfer argues that natural gas’ accelerated buildout came from how it embedded itself into what he calls the “economic plan” of transmission owning utilities, like PSEG, the utility that manages Princeton’s area, and the regional transmission operators, like PJM. Building large transmission lines for natural gas plants became the default for developing the grid.
Although PJM transmission plans recognize that large amounts of wind, solar and storage are coming, the transmission-owning utilities, who are the principal investors in new transmission, have not embedded renewable energy grid infrastructure into their investment plans in quite the same way. “I think the mental blueprint for investing in transmission for wind and solar is not there.” Alderfer said. “It’s still a battle between natural gas and clean energy visions. As long as you have that, I don’t think you’re going to have transmission approved fast enough.”
This war also plays out in how the energy market of PJM is designed.
“The wholesale market itself, in PJM… is not well designed to bring on solar. It’s well designed to bring on gas,” Alderfer said. As a wholesale, “deregulated” market, PJM provides energy by making generators bid for the price at which they will supply, creating a competitive environment in which power generators compete with one another to produce electricity for the lowest possible cost.
Yet the way PJM sets the price for electricity favors fossil fuels. Given the predominance of natural gas generation in its system, PJM most often adjusts the price it will pay for electricity based on the marginal cost of producing an additional unit of electricity from natural gas (mostly determined by the price of fuel). Should this fuel price rise due to supply shortages or disruptions in the market, generators will raise their bid prices accordingly, and PJM will raise their price of electricity to reflect the increase. As a result, they provide natural gas plants with enough extra profit to offset the surplus costs of electricity generation. This marginal-price market design gives financial security to fossil fuel plants because they can be reasonably certain the electricity market will ensure their profitability.
Fossil fuel plants are what’s known as “price-setters,” as they set the market price of electricity based on the marginal cost of its generation. Solar, and other renewables, on the other hand, are price “takers.” The marginal cost of generating electricity via solar panels is close to zero (one does not have to pay the sun to gain access to its energy). Therefore, solar farms will accept (take) any price set in the market by fossil fuel generation in their pursuit of recovering and making a return on their initial investment capital. Whatever the price, the solar farm may as well take it.
Yet this structure comes with a cost, as solar farms’ revenue hinges on a price of electricity over which it has no control. They are “at the mercy of a market that was framed by fuel-based resources,” according to Alderfer. In Princeton’s case, once it moves forward with its next solar expansion, it may encounter a market in which natural gas fuel prices set the price of electricity below what the University needs to make a return on investment.
Moreover, because of natural gas price volatility, PJM’s energy prices can’t be predicted and prepared for after more than five years. This is a risky proposition when solar projects only move forward if they’re sure they can achieve returns on initial capital over 25 years—far past what can be predicted. As a result of these sources of volatility and uncertainty, justifying an investment like Princeton’s becomes even more tricky.
To make matters worse, as more and more renewables come online, electricity market prices could decrease by up to 25 percent in the PJM area according to Princeton researchers. Princeton as a University will likely remain relatively unscathed by this “price erosion,” because it consumes enough electricity to provide its own market for its solar output, and would receive a relatively stable price for electricity based on its expansion costs. However, for solar developers eyeing grid-connected solar projects that rely solely on wholesale energy markets, price erosion in these markets could render their projects unprofitable—or, at least, profitability may be too uncertain for them to move forward with some projects. “It’s pretty tough to invest a billion dollars in new resources if you don’t know how much revenue you will receive,” Alderfer said. And if solar companies can’t find enough investors, they can’t build their farms.
The physical and financial structures that were established for older forms of energy aren’t suited to variable renewable energy sources like solar. Unless policymakers and regulators can redesign these structures, they will hamstring the accelerated deployment of renewable energy for years to come.
“At the moment, we’re slapping these things on the ground”
“The design is to hide them. Not to make them nice,” Tatiana Choulika told me. “That’s where the investment is: put big berms, so nobody sees them.”
Choulika works as a Principal Landscape Architect for James Corner Field Operations, and worked on the landscape architecture of both of Princeton’s solar projects as part of the company.
Designing the landscape of Princeton’s solar projects along Route 1, Choulika and her team devoted the most effort towards concealing the solar panels. “The main concern was, ‘can I see the panels?’” she said. The team drew up countless drawings for the earthen embankments which now serve to disguise the solar farms South of Lake Carnegie.
Their work of concealment reveals an understandable anxiety amongst solar developers that people will oppose solar projects on wide open spaces: they look ugly and take up land that could be devoted to more traditional uses such as agriculture. However, this need not be. Choulika sees this perception of the ugliness of solar farms not as inherent to the technology, but is a design question. Currently, most solar farms are composed of hundreds of rows of panels that take up a rectangular plot of land, often formerly used for agriculture. “It used to be so expensive to [install] a solar panel that designing anything more than just [struts] to put them on was just too much money,” Choulika said. The current aesthetic of today’s solar farms came from a utilitarian view of economic necessity. But it has also meant that the development of sophisticated and attractive architectural design for solar farms has been stunted. “In order for public acceptance… we need to invest in design,” Choulika said. “At the moment, we’re not.”
Solar is much cheaper to build, so those design constraints no longer hold. While the IRA and other funding incentives allot money towards the design of solar panels and farms, very few economic resources have been devoted to the design of the rest of the site. “The panels are just a material, a piece of the puzzle that has to be put together,” Choulika said. To accommodate the aesthetic needs of a whole site will take effort and architectural imagination. “If people want solar panels to be beautiful, and to be set in the landscape in a manner that is attractive,” Choulika said, “then we’re just going to have to think about it differently, [and] spend the time to make them attractive.”
Choulika imagines this work will be necessary to gain public support for solar projects; if people see beautifully arranged solar farms elsewhere, they may be willing to accept a similar farm in their area. Well-designed solar farms could allow the technology to embed itself into the public consciousness – and thus hasten the net-zero energy transition. And it isn’t just about aesthetics; investing in landscape design offers an opportunity for solar farms to do more than simply generate electricity.
“We have an opportunity to really make sustainability irresistible.”
Ultimately, the transition to a decarbonized society requires renewable energy generation like solar to be designed into all aspects of the energy nexus, from land use, to generation, to market sale, to transmission, and finally to consumption. This work isn’t just for utilities, for large institutions like Princeton, or for policymakers (though they will play a large role). Individual residents across the US must also support the deployment of solar to meet our climate goals, both on the utility-scale and at a more local level. And laws like the IRA have constructed it to be this way
That’s because the IRA dispenses money for infrastructure like residential energy-efficiency and renewable installations as tax credits. These tax credits may rapidly advance renewable infrastructure adoption, especially because they are uncapped: lawmakers didn’t place any upper limit on the amount of money the IRA can dispense through them. Indeed, while the Office of Management and Budget estimated the investment of the IRA’s climate spending to be $390 billion, Goldman Sachs put the number much higher, at a staggering $1.2 trillion. Their study reached its new figure precisely because they predicted a wider use of renewable tax credits – and is possible because of their uncapped status. But the IRA risks underspending, too.
“[The Inflation Reduction Act] is only as powerful as it is adopted and used as intended,” said Christine Symington, Executive Director of Sustainable Princeton. “So it will be successful if there is a large uptake of people making use of those incentives on the consumer side, to implement energy efficiency, building and vehicle electrification, and renewable energy.”
Because it allocates so much money through tax credits, if no households or businesses take advantage of them, no money would be dispensed. As a result, Sustainable Princeton hopes to encourage people to take advantage of these incentives by educating residents in the municipality of Princeton about rooftop solar and electric heat pumps. But their work also helps create a narrative shift around solar that will play a critical part in its social normalization, which is a shift needed across all sectors of solar development.
“‘You should subscribe to community solar,’ is one way to look at it,” Sustainable Princeton Communications and Outreach Manager Elana Berk said. “‘I’m so excited to be part of this movement’ – at least to me, … that’s where I feel like we can kind of help push past that barrier and reframe [the transition] as a joyful, exciting thing. It’s irresistible. You just want to do it.”
“We are very wasteful; we don’t use the land properly.”
Back to the sheep. In our conversation, Choulika stressed the importance of layering uses above, below and between solar panels as a design paradigm necessary to integrate solar into our daily realities. Solar farms can take design one step further through a sustainable design principle that Choulika advocated for, called “layering uses.”
According to Choulika, devoting large swaths of land purely to solar is a waste of space because it blocks that land from any other use. She pointed to instances of people cutting down forests to build solar farms, and times when farms built on agricultural land drew heavy flak from farmers who opposed the diversion of cropland, as prime examples of the tension between solar generation and land-use efficiency. But this tension isn’t necessarily a given. Instead, solar panels can coexist with one or even multiple other uses when layered correctly.
Some of Princeton’s solar farms demonstrate this concept. In its newest solar expansion, the University installed panels above parking lots dotted across campus (West and North Garage, Lot 20, etc.). It managed to locate 27% of the new solar capacity on already-occupied land by layering uses in such a way.
In addition, Princeton employs a rudimentary layer-stacking technique on its solar fields across from Lake Carnegie with an unlikely second use: sheep grazing. It employs Julie Bishop, founder of Solar Sheep LLC, to send sheep to pasture in the West Windsor fields. In the spring and summer months, Bishop brings the sheep to graze on the “fenced in flat, green, beautiful” grass around, beneath and between each row of panels – with the mutual benefit of ensuring that this grass never grows high enough to block light from reaching the panels.
Sheep are a creative, and certainly unique, solution to the problem of how to effectively maintain solar fields. Bishop’s sheep emit far less carbon dioxide than mechanical mowers, can reach otherwise inaccessible areas below panels, and move through the farm with an ease that human mowers can’t replicate. “It’s a wonderful place for the sheep. They have all the grass they want, and all the shade they want,” Bishop said. “They’re low enough that they don’t have to worry about bumping their heads.”
Bishop is possibly the first person in the country to put her sheep to pasture on solar fields. Her Katahdin sheep are an American composite breed originally created by an amateur geneticist to keep the brush below large power lines in check without traditional mechanical or chemical tools. Indeed, at Princeton, Facilities only has to mow the solar fields once or twice a year, mostly to control the invasive plants that sheep don’t seem to have an appetite for. Bishop’s herd exemplifies a successful layering of uses on agricultural land. She can raise her lambs on the fields, selling them as pets and for meat, using the same space in which Princeton generates electricity for campus.
In fact, sheep are only the first step towards complex layered design, because of their compatibility with how solar farm infrastructure is currently designed. “Solar companies don’t have to do a lot of changing to their typical design” to accommodate the sheep, Bishop said. For instance, unlike other animals that could potentially do the job (such as goats), they don’t have any particular urge to jump onto the solar panels above them. “Sheep just happened to get lucky,” she added.
But the ambitions for layering uses with solar don’t end with sheep. Choulika envisions a more elaborate “stacked use” solar farm that involves elevated solar panels to accommodate the cultivation of crops below. While this intensive form of “agro-voltaics” wouldn’t be suitable for large-scale agriculture, it could ease public concerns about how much land solar will have to take up in the future. She also drew attention to new forms of layered use that are becoming possible due to advances in new technology: panels in between rail tracks or attached to exterior walls on buildings, geothermal wells underneath solar fields.
“The problem that we have with the environment nowadays is that we are very wasteful; we don’t use the land properly,” Choulika said. “Nature does a much better job on its own than we do.” With solar’s layering potential, we might begin to catch up.
Chapter 5: The Road Ahead
Solar’s advance extends far beyond Princeton’s borders. With it comes the challenge of fundamentally transforming the way we design and imagine electricity generation, as policymakers, energy companies, architects, shepherds, and as everyone who drives past the slender blue panels of newly-constructed solar farms. While economic incentives boost solar development forwards, more will be required to clear the path to a decarbonized nation and world. “It also needs a broader story,” Alderfer said, “and a clearer vision.”
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