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University Evaluates Mobile Solar Car Port for EV Charging with APPA Funding

North Carolina State University has evaluated the feasibility of a prototype portable solar carport with an integrated electric vehicle charger with the help of funding from American Public Power Association’s Demonstration of Energy & Efficiency Developments program.

The goal of the project was to assess if the solar carport has the potential to address low solar adoption rates for low to middle income households, as well as for commercial customers.

To assess the technology, the FREEDM Systems Center, the power systems and electronics research center within North Carolina State University’s Department of Electrical and Computer Engineering, set out to gather opinions of potential customers, and suggest design changes from user feedback.

The device being tested, a Mobile Electric Generating Appliance, was developed by Gismo Power and consists of an aluminum frame supporting nine bifacial photovoltaic solar panels and a SolarEdge inverter. The unit is portable and is equipped with casters to make it moveable.

In 2022, the MEGA unit cost about $10,000. Since then, prices on all components have increased, therefore, the researchers said, the 2023 cost of a MEGA is unknown.

The MEGA requires a 240-volt alternating current, 40 ampere grid-connected power source. Maximum power output is 4.1 kilowatts from the solar panels. The inverter’s peak rating is 9 kW.

The initial plan of the FREEDM researchers was to demonstrate the unit at multiple locations and gather user feedback. Due to liability concerns and other restrictions, however, the researchers instead focused on a long-term demonstration at the FREEDM parking deck on the North Carolina State University campus.  

Restrictions on using multiple locations meant that the researchers were not able to collect detailed customer feedback as planned. Nevertheless, the researchers said the overall reception and day-to-day usage by multiple staff at FREEDM was very positive.

“The unit performed extremely well for a full year with no serious issues,” Ken Dulaney, project manager at North Carolina State University, said via email.

The researchers found that the solar output from the MEGA unit, which was in a location with no shading and a highly reflective surface. was higher than the inventor estimated. Over the course of the project, the MEGA produced 6.17 megawatt hours from the solar panels and provided 3.57 MWh for electric vehicle charging.

The project team noticed an unexplained trend in the data for cloudless days with many output dips around noon that can result in 25 percent power reduction during peak generation hours. To date, there is no clear trend or explanation for that anomaly, the researchers said.

“The inventors still have work to do before mass adoption, but the concept is strong,” Dulaney said. “We would not be surprised to see MEGAs or similar products available on the market in three years.”

“Our perception,” Dulaney added, “is that the early adopters will be customers that drive EVs and already have net metered, residential solar systems. The price point of $10,000 seems too high for low income customers but affordable for middle and high income.

As part of the project, the North Carolina State University researchers also wanted to understand the impact of hundreds or thousands of MEGAs would have on a utility distribution grid.

APPA did not have a role in that part of the project, but FREEDM provided the results of the grid impact study as part of its DEED cost share requirements. The grid impact study was funded by the National Renewable Energy Laboratory as part of the American Made Solar Prize.

For the impact study, a team of North Carolina State University graduate students combined real world output from the MEGA at FREEDM with available data sets from the Pecan Street Project in Austin, Texas, to estimate grid impacts.

“The main take away from the grid impact study is that it reinforced the results of previous studies: managed EV charging paired with residential solar can provide benefits to the distribution system operator,” Dulaney said.

The total project budget was $39,900, of which APPA provided $10,000 in DEED funding, The National Renewable Energy Laboratory provided $24,900 of funding for the grid impact study. FREEDM provided the remainder of funds.

The key takeaways from the project are that “this is a good idea and a product that performed very well,” Dulaney said. “Second,” he said, “is that utilities should be prepared for innovative solar technologies to be adopted by their residential and commercial customers.”

North Carolina State University is the largest institution in the University of North Carolina System with 38,000 students and 8,500 employees. The university manages an energy grid with five utility plants and a network of steam and chilled water pipelines. The system’s total electric load across three main campuses is around 45 megawatts.

Click here for additional details on the DEED program.