Market Insights

Rooftop PV + EVs = Solar Power Synergy

October 11, 2023 by Jake Hertz

Researchers believe solar rooftops can power a city while charging electric vehicles, thereby reducing carbon dioxide emissions. They propose trying out their idea in Paris, France.

As cities grapple with the urgent need for decarbonization, the SolarEV City Concept emerges as a potential game-changer. This innovative approach synergistically combines rooftop solar panels with electric vehicles, aiming to reduce both CO2 emissions and energy costs.


The SolarEV City concept relies on rooftop PVs and EVs working together.

The SolarEV City concept relies on rooftop PVs and EVs working together. Image used courtesy of the Texas Solar Energy Society


Paris, the birthplace of the 2015 Paris Climate Agreement, stands as a symbol of global efforts to combat climate change, and now it’s serving as a testing ground. While the SolarEV concept faces challenges, a recent study from Tohoku University believes that Paris and its surrounding region, Ile-de-France, may be the ideal spot for the job.


The SolarEV City Concept

The SolarEV City Concept is an innovative approach to urban sustainability that synergistically combines rooftop photovoltaic systems (PVs) with electric vehicles (EVs). The core idea is to use solar panels installed on rooftops to generate electricity, which not only powers the buildings but also charges the electric vehicles. 

A major tenet of this concept is that the EVs serve a dual purpose: they not only replace gasoline and diesel vehicles, thereby reducing CO2 emissions, but act as mobile energy storage units. When the sun isn't shining, the stored electricity in the EVs can be fed back into the home or the grid, effectively turning them into a decentralized energy storage system that enables a transition to renewable energy.

This concept is particularly significant given the urgent need for decarbonization in urban settings. Cities are the epicenters of energy consumption and are responsible for 71–76% of global CO2 emissions, according to the researchers. The SolarEV City Concept presents a possible solution. For instance, studies have shown that in cities like Kyoto, implementing this concept could lead to a 60-74% reduction in CO2 emissions and a 22-37% decrease in energy costs by the year 2030.


Roadblocks Challenge SolarEV City

Realizing the full potential of the SolarEV City Concept faces several challenges that stem from urban infrastructure, climate conditions, and economic factors. 

One of the most significant hurdles is the variable effectiveness of the technology across different urban landscapes. Densely populated cities with limited rooftop space, such as Tokyo and Kawasaki, offer fewer opportunities for installing solar panels, thereby reducing the potential for CO2 emission cuts and energy cost savings. This spatial limitation is even more pronounced in high-rise urban areas where the rooftop-to-population ratio is low.

Another challenge is the lack of research and implementation strategies for high-latitude cities. In these regions, solar insolation and electricity demands are seasonally inversely correlated, mainly due to increased heating requirements in winter. This seasonal variability complicates the effective utilization of solar energy and requires more sophisticated energy storage and management solutions.


The Makings of an Ideal SolarEV City

In their study, the research team found that Paris, France, could be the ideal city/region to implement a SolarEV concept.

From a practical standpoint, Paris and its surrounding region, Ile-de-France, offer unique opportunities for the deployment of SolarEV technology. While the city itself may have limitations in terms of rooftop space — able to supply only about 30% of its electricity needs through rooftop PVs — the surrounding region compensates for this. 


Paris and its surrounding region may be the ideal place for a SolarEV City.

Paris and its surrounding region may be the ideal place for a SolarEV City. Image used courtesy of TechXplore.


The Ile-de-France region, characterized by many low-rise buildings, has the potential to meet 78% of its annual electricity demand if 71% of rooftops were covered with solar panels. Incorporating EVs as storage batteries could lead to a 23% reduction in energy costs by 2030.

Moreover, Paris's dense population and extensive public transportation network could facilitate the rapid adoption of electric vehicles, making the SolarEV concept more effective.