NREL Explores Benefits of Solar-Powered Charging For Plug-in HEVs

Jan 24, 2008 2:51 PM
by David Morrison, Editor-in-Chief, Power Electronics Technology

A solar-powered recharge station for electric and plug-in hybrid electric vehicles (PHEV) built by the Department of Energy’s (DOE's) National Renewable Energy Laboratory (NREL) will allow researchers to explore the potential benefits of renewable energy and PHEVs to consumers and electric utilities. Developed as part of a project run by NREL senior engineer, Tony Markel, the recharge station consists of a 3.5-kW solar array that provides shade and power for two PHEVs.

The solar array was supplied by Envision Solar, which created its Solar Tree design specifically for NREL’s renewable recharge station. This station is located at NREL’s South Table Mountain site in Golden, Colorado. The structure features 20 photovoltaic panels atop a single-post, grid-tied parking canopy. The PV canopy, tilted at a 30-degree angle, was designed to produce an estimated 10-kWh while providing two shaded parking spaces. But Markel notes that the installation actually produced 14 kWhr during its first day of operation.

The Solar Tree design incorporates one 120-V outlet per parking space and supports 20 photovoltaic KC200GT Kyocera Solar modules. An additional outlet supplying 240 Vac is also included to accomodate higher-energy vehicles that may be available in the future. The first parking space is reserved for NREL's Toyota Prius PHEV and the second parking space will accommodate other visiting vehicles for experimental purposes.

“Envision’s Solar Tree design provides NREL with key equipment to explore the linkage between renewable energy resources and transportation energy demands,” says Markel. “Collecting energy from the sun and using it as a fuel for EVs and PHEVs helps us address our dependence on imported petroleum.”

Beyond using renewable energy to reduce petroleum consumption, the solar-powered recharge station will be able to supply excess energy back to the grid. What’s more, when a PHEV is present, its battery can be used by the utility as a “dispatchable” generator,” provided a communications link is present from utility to vehicle.

Being able to take advantage of the vehicle’s battery overcomes one of the limitations of solar power—the variation in a solar panel’s power output over the course of the day and the time of year. Markel notes that a vehicle is typically on the road about 5% of the time, so the potential is there for doing more with the very expensive battery installed in the hybrid.

Want to use this article? Click here for options!
© 2007 Penton Media, Inc.