Research led by scientists at Switzerland’s University of Geneva analyzed the impact of EVs on solar-powered energy communities. The study examined how 0%, 50%, and 100% EV penetration affects solar sizing, investment incentives, and low-voltage distribution grids.
“The research presents a multi-disciplinary approach for comprehensively assessing solar energy community investment drivers and the individual and mutual impact of PV generation and electric vehicles on the distribution grid,” researcher Selina Kerscher told pv magazine. “No other study evaluates the impact of electric vehicles on the investment decision of a solar energy community, and the individual and mutual impact of distributed solar PV and electric vehicles on a real low-voltage grid over an entire year.”
The simulated energy community was in northern Spain and included 360 households. PV panels had a nominal power of 405.49 W. All homes had smart meters, and the model used a European three-phase unbalanced distribution system with 184 buses. Because only detached houses had private EV parking, full EV penetration meant 55 households with EVs; 50% penetration meant 28.
Charging behavior
In both scenarios, 55% of households had full-time workers (five to 11 hours outside the home daily), 30% were part-time (three to six hours), and 15% were unemployed. One-third of EV owners drove a Fiat 500e, one-third a Kia Niro, and one-third a Tesla Model 3. Half charged at home, and half used external chargers such as at workplaces. Two charging scenarios were tested: uncontrolled/direct charging at maximum power from the connection point, and even charging at uniform power during idle time.
The study included three energy-community settings: one with no feed-in remuneration; one in which only detached houses could install PV with feed-in remuneration; and one where all households could install PV with feed-in remuneration. Investment optimization was conducted for eight representative days and for a full year. The assumed integrated PV investment cost was €1,400 ($1,625)/kW. Contracted power cost €0.11/kW per day, and taxes and surcharges were €0.139/kWh.
“The study highlights the effects of the load shape and feed-in regulation on the viability of additional PV panel investments,” said Kerscher. “Feed-in remuneration makes more surplus generation cost-effective and offsets the cost-optimal PV capacity from the point of minimal load-generation mismatch. The more loads can be shifted to PV generation hours, the more additional investments in PV capacity become viable, further augmented by feed-in remuneration.”
Grid impacts
Results showed that uniform EV charging increased PV investment viability compared to uncontrolled charging and helped reduce excessive voltage drops. The study also found that optimizing for just eight days overestimated benefits by 32% in the 0% EV scenario.
“The occurrence of over-voltage from distributed solar generation more than doubles from 4.9% to 10.6% when increasing the PV penetration in the energy community by only 9% with an unfavorable panel distribution,” the scientists added. “Increasing the PV penetration by 59% with a more optimal panel allocation yields a comparatively lower occurrence of overvoltage of 10.0% highlighting the need for informed community planning.”
The scientists presented their results in “Electric vehicles in solar energy communities—Impact on asset dimensioning and the low-voltage grid,” published in Energy Conversion and Management: X. Scientists from Switzerland’s University of Geneva, Germany’s Technical University Braunschweig and Norway’s Norwegian University of Science and Technology participated in the study.
“Follow-up research aims at identifying the potential of energy communities investing in solar and storage technologies in urban environments by correlating easily accessible urban characteristics with the outcomes of optimization and simulation models,” concluded Kerscher.
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