Imagine if California could generate enough energy to power the entire state three to five times over—not by building massive solar farms in the desert or constructing sprawling wind farms, but simply by harnessing the power of rooftops and other urban spaces.
The idea sounds almost too good to be true, but it’s backed by groundbreaking research that’s challenging everything we thought we knew about solar energy.
New research led by Dr. Rebecca R. Hernandez from the Carnegie Institution for Science shows that the solution to California’s energy needs might be right under our noses.
Instead of sacrificing vast tracts of land or pristine wilderness to large-scale solar projects, the study suggests that we can utilize urban and suburban spaces—specifically rooftops and underused public areas—to generate more than enough renewable energy to meet the state’s electricity demands, and then some.
“Solar facilities integrated into the urban environment cause the least land-cover change and have the lowest environmental impact,” says Hernandez.
The study has ignited a fresh conversation about how we approach solar energy and where we place it—because the future of clean energy might not look like anything we imagined.
The Real Answer to California’s Energy Needs? Urban Solar
When most people think of solar power, they likely picture massive fields of panels in remote deserts or vast offshore installations.
The idea is that we need large-scale solar farms to meet the energy demands of a state as big and energy-hungry as California.
But Hernandez’s research presents a game-changing perspective: California’s urban landscape itself could provide more than enough space to generate the clean, renewable energy the state needs.
To understand the scale of this idea, consider this: California uses about 4,000 terawatt-hours of electricity annually.
The study found that by covering 6.7 million acres of rooftops and 1.6 million acres of public parks with a mix of photovoltaic (PV) solar panels and concentrating solar power (CSP) systems, the state could generate a staggering 21,000 terawatt-hours of energy per year.
Here’s the breakdown:
- 15,000 terawatt-hours from photovoltaic panels installed on rooftops and small-scale installations.
- 6,000 terawatt-hours from concentrating solar power, which uses mirrors to concentrate sunlight into a small area, generating concentrated heat that can then be converted into electricity.
That’s up to five times the total energy California uses each year.
What’s even more incredible is that none of this power generation would require clearing new land or displacing natural habitats.
In fact, Hernandez’s study points out that the space is already available—we’ve already paved over it.
Challenging Conventional Wisdom: The Myth of ‘Space for Solar’
Let’s break away from the common narrative for a moment.
Most people believe that the key to generating large amounts of solar energy lies in building massive solar farms in remote areas—far away from cities and the natural environment.
This has led to years of debates over whether these farms disrupt wildlife habitats, require excessive water usage, or are simply too far from where energy is needed.
The idea of using urban spaces for solar power, especially rooftops and parks, is still an unfamiliar one.
But Hernandez’s research, published in Nature Climate Change, presents a contrarian viewpoint that challenges this assumption head-on.
Instead of imagining solar energy as a luxury for large, empty plots of land, Hernandez shows that we’ve already taken the land we need—we just need to repurpose it.
Cities, suburbs, and even degraded lands can offer an abundance of solar potential without the environmental trade-offs often associated with large-scale solar farms.
Think about it: rooftops across California could collectively host millions of solar panels.
Public parks, parking lots, and even vacant lots could host small-scale solar installations or concentrating solar power plants, harnessing the full potential of urban spaces to power homes and businesses without sacrificing natural land or ecosystems.
This approach isn’t just possible—it’s scalable, and it’s becoming more and more feasible as solar technology advances.
Solar Power Technology: The Perfect Match for Urban Spaces
Hernandez and her team looked at two types of solar technology that work particularly well in urban environments: photovoltaic (PV) panels and concentrating solar power (CSP).
- Photovoltaic panels, the familiar flat solar panels that capture sunlight and convert it into electricity, are ideally suited for rooftops, parking lots, and other available spaces. They can be installed without disturbing the surrounding environment, making them a perfect fit for cities.
- Concentrating solar power (CSP), on the other hand, uses giant mirrors to focus sunlight onto a small area, concentrating it to generate intense heat. This technology requires more space than PV panels but can still be incorporated into urban parks or unused public spaces where heat can be harnessed effectively.
What’s particularly exciting is that the study found a combination of both technologies would be the most effective.
By mixing these two systems, urban and suburban spaces could be transformed into self-sufficient energy hubs, providing enough electricity to power not just the homes and businesses within them, but far beyond.
How Much Space Are We Talking About?
Here’s where things get even more fascinating.
Hernandez’s study estimated that 6.7 million acres of rooftops could be used to install photovoltaic solar panels across California.
To put that into perspective, that’s about 10% of the land area of California—not counting the space that’s already built up for infrastructure like roads, highways, or buildings.
On top of that, there’s the potential to convert 1.6 million acres of public land (like parks, abandoned lots, or degraded lands) into concentrating solar power installations.
In total, we’re looking at about 8.3 million acres of urban and suburban land that could be utilized for solar power generation without touching ecologically sensitive lands or wilderness.
Imagine the impact of these small-scale, distributed installations: not only would California have more than enough energy to power itself, but it would also avoid some of the complications and costs associated with large-scale solar farms—such as land acquisition, transmission infrastructure, and water use.
No Need for Deserts or Oceans: The Urban Solar Revolution
It’s easy to assume that solar energy requires large, remote areas like deserts or offshore regions.
The belief is that these remote spaces are the only places vast enough to install the necessary infrastructure for solar energy to make a meaningful impact.
But Hernandez’s study makes a compelling case for the urban solar revolution—proving that we don’t need to look to the desert or the oceans to achieve our energy goals.
The concept is simple: by focusing on already-occupied land, such as rooftops, parking lots, and degraded land, we can avoid the environmental and logistical concerns of building large-scale solar projects in more remote areas.
This could also drastically reduce the costs and inefficiencies associated with building new power lines or transmission infrastructure.
By using land near roads and existing transmission lines, we make the entire energy system more efficient and easier to manage.
No need to disrupt sensitive ecosystems or invest heavily in transportation infrastructure.
Taking It Beyond California: A Global Solution
While the study focused on California—one of the sunniest and most solar-friendly regions of the US—the insights are easily applicable to any sunny, urban area around the world.
From parts of Spain to India, cities are rapidly expanding and energy demand is on the rise.
The same principles can be applied globally, allowing countries to harness the power of their own urban environments to meet energy demands sustainably.
In fact, urban solar power might become the key to solving the global energy crisis.
With an ever-growing population and increasing urbanization, it’s becoming clear that cities—not deserts—could hold the key to achieving a clean, sustainable energy future.
The Path Forward: Scaling Urban Solar
So, what needs to happen to make this vision a reality?
The path forward lies in policy changes, technological innovation, and collaboration across sectors.
Governments and private enterprises need to incentivize the installation of solar panels on rooftops and public spaces.
Utilities should prioritize making it easier for homeowners, businesses, and communities to install and maintain solar power systems.
Furthermore, new technologies in energy storage and smart grids will allow us to store excess energy and distribute it more efficiently, ensuring that even intermittent sources like solar can provide a steady and reliable power supply.
The research is clear: California doesn’t need to look to the desert or the oceans to solve its energy needs.
The solution is already right under our feet.
Conclusion: Solar Power Is Already Here
The future of solar power isn’t in remote, untouched deserts. It’s in our cities, on our rooftops, and in our public spaces.
As Hernandez’s groundbreaking research shows, urban solar power could power California five times over—without harming a single natural habitat.
If California—and the world—embraces this approach, we could see a future where sustainable energy isn’t just a goal; it’s a reality built right into the cities we’ve already created.
The time to rethink solar power is now.
