London, UK – While cities continue to expand outward and upwards, some of the most promising opportunities for a greener future are already built into our infrastructure. Innovation, in fact, often begins with rethinking the spaces we already take up.
Space that has arguably remained out of sight and out of mind – until recently. A new study published in Nature Energy suggests the rooftops of Europe’s buildings could generate as much as 40% of the European Union’s electricity demand by 2050.
The analysis examines the solar potential of buildings across the EU at the level of individual structures, looking separately at residential and commercial properties: what it reveals is a scale of opportunity that has largely gone untapped.
Across 271 million buildings, researchers estimate rooftops could host about 2.3 terawatts of solar photovoltaic capacity. If the region used today’s technology, that infrastructure could amount to about 2,750 terawatt-hours of electricity each year, a big share of the energy required to create a fully renewable European power system.
Those numbers look promising, but the reality is that deployment has been slow, with only one in ten rooftops across Europe actually having solar installed; leaving the vast majority of that potential untouched.
Where the opportunity stalls
According to Eurostat, just 26% of building energy use comes from electricity, meaning everything from heating systems to industrial processes still heavily rely on fossil fuels. Expanding rooftop solar could play a major role in shifting that balance.
Scholars point to commercial and industrial buildings in particular, which offer some of the fastest opportunities for scale. In fact, they estimate that more than half of the EU’s 700-gigawatt solar capacity target for 2030 could theoretically be met by using non-residential rooftops alone.
For many working in the sector, the slow rollout isn’t a question of whether solar works: the bigger challenge is simply figuring out where to build first.
Daniel Domingues, founder of energy-software company Planno, an AI-powered prospecting software that helps solar companies identify and pre-qualify commercial and industrial rooftop opportunities, says much of Europe’s building stock has simply never been systematically evaluated for solar potential.
“The potential has always been there, but only a fraction of Europe’s commercial and industrial buildings have actually been analyzed in a meaningful way,” Domingues told EU Reports.
Traditional surveying methods remain fragmented and time-consuming, he explained. Developers often rely on manual site visits, scattered building data or outdated registries to identify viable projects.
“Across the sector, surveys are still slow and fragmented,” Domingues stressed. “And when you add the complexity of different regulatory frameworks, grid constraints, and incentive schemes across EU countries, it becomes even harder for investors to prioritize where to start.”
The missing software layer
Domingues believes the industry’s bottleneck is not solar technology itself but the lack of a scalable system for identifying opportunities.
“What’s missing is a software layer capable of quickly identifying and prioritizing buildings where solar projects are most feasible and profitable,” he said.
Planno leverages recent advances in geospatial data and artificial intelligence in a way that makes rooftop prospecting scalable. The formula combines satellite imagery, building footprints, weather patterns, and energy demand datasets to screen thousands of viable buildings so as to determine if they are technically fit for solar installation.
Such digital mapping will likely become essential in the EU as governments attempt to accelerate deployment across dense urban environments.
A trend spreading across Europe
Portugal has emerged as one of the clearest examples of how this shift is already playing out, with Planno’s technology being utilized through partnership with renewable energy firm Spark Wave Energy.
According to Tiago Andrade e Sousa, CEO of Spark Wave Energy, the country has rapidly expanded renewable energy generation over the past several years: “Portugal is becoming a global example of fast, smart renewable-energy adoption.”
In January 2026 alone, 80% of Portugal’s electricity came from renewable sources, largely driven by hydroelectric and wind power.
However, solar is a cheap renewable source that the country is actively developing. Between January and September 2025, Portugal generated 10,759 gigawatt-hours of solar PV energy, up significantly from 8,544 GWh during the same period in 2024.
Developers are privy to this, increasingly working with platforms like Planno to quickly and efficiently identify where the opportunities lie above us.
For Domingues, this is precisely where the energy transition is heading.
“Once you can map opportunities at scale, you move from guessing where solar could work to knowing where it should be built first,” he noted.
Governments and utilities across cities in Germany, the Netherlands, and France have already begun deploying digital maps that estimate rooftop solar potential for every building in a city or region.
These publicly-available solar maps allow anyone to evaluate rooftop viability instantly using satellite data and building characteristics, painting a future in which Europe’s solar future depends not on massive solar farms but from already existing infrastructure – the core of Europe’s cities and industrial parks.
For Domingues, the technology to facilitate such a transition already exists:
“Reports like this are important because they quantify something the industry has known for years. The opportunity is there; now it’s about using the right data and tools to move from potential to real installations.”
Featured image: Nuno Marques via Unsplash+
Disclosure: This article mentions clients of an Espacio portfolio company.
