Author:
Ally Winning, European Editor, PSD
Date
03/25/2026
PDF
Why are solar and EVs not being used to complement each other more frequently?
EVs and renewable energy seem like a perfect partnership. In many countries, electricity is charged at different rates throughout the day, depending on demand. EV’s can act as a battery, storing the energy generated by solar panels during off peak times, and releasing it back onto the grid at peak times. Even without a source of renewables, EVs can be charged at low cost times, and supply power to the home, or feed it into the grid when electricity is more expensive. It isn’t hard to see how this benefits the grid by reducing demand at peak times. Although the concept seems to make a lot of sense, it hasn’t seen widespread adoption so far. A study by North Carolina State University and University of Colorado Denver has looked into the subject to investigate what is holding the process up and suggest possible paths forward to adoption. It is estimated that there are currently around 4 million EVs on the road in the US, and they are making up an increasing proportion of new vehicle sales. If they were used as batteries, those EVs could go a long way to help make the grid more resilient in times of rising demand.
“EVs are parked 95% of the time, and when EVs are parked they’re essentially a battery on wheels. That battery storage can be used to feed energy back into the power grid – and EV owners can get paid if their vehicle is supplying energy to the grid,” Serena Kim, corresponding author of the study and an assistant professor in North Carolina State University’s School of Public & International Affairs says, “this can be useful to the grid because the vehicle may be parked – and providing energy – during periods of high energy demand, which is normally during the late afternoon or early evening. Feeding energy into the grid can also be useful if the vehicle is parked overnight, when some renewable energy sources – such as solar panels – are not producing electricity.”
Kim continues, “we know that a lack of clear compensation mechanisms is a variable. We know that limited infrastructure plays a role. But we wanted to get a deeper understanding of all the factors in play, as well as which factors may be most important, in order to support the promotion of V2G efforts in the future.”
For the study, researchers conducted interviews with 42 stakeholders representing various relevant interests, including power utilities, EV manufacturers, local and state governments, school districts, and EV owners who participated in V2G pilot projects. The interviews were designed to collect information about the barriers to V2G adoption. What are the stakeholder perceptions of V2G? What have their experiences with V2G been? What do they view as the biggest obstacles? And what do they see as the best path forward for V2G?
“A key finding was that V2G adoption is a coordination problem rather than a technology problem,” says Kim. “On the one hand, utilities want to see more V2G-capable vehicles before they invest in V2G infrastructure and programs to compensate EV owners. On the other hand, EV owners are unlikely to participate in V2G programs if they don’t know how they will be compensated. And potential EV buyers can’t plan on defraying the cost of buying an EV if there is no infrastructure in place to support V2G programs. It’s a complex problem. Essentially, utilities are likely to play a central role in coordinating these problems if V2G programs are going to move forward. But there is currently little incentive for those companies to make the investment, beyond the potential to improve grid resilience.”
The study also found that this challenge is compounded by a patchwork of regulations and policies that vary across jurisdictions, with relevant rules differing from state to state and even at the local government level. This makes it harder for automakers, companies that build and operate EV charging networks, utilities, and other stakeholders to plan and invest at scale. Harmonizing technical standards and interconnection requirements is an essential step toward scaling V2G programs.
The paper describing the study, “Electric Vehicles as Grid Resources: Barriers to Vehicle-to-Grid (V2G) in the United States,” was published in Utilities Policy.
This work was done with support from the National Science Foundation
