SD Zoo Solar-To-EV System Is The Real Deal

If you’re going to do a solar-to-electric-vehicle system, you might as well do it right. (This is a topic we explored in a story a few months ago.)

Looks like the San Diego Zoo did it right.

With 90 kilowatts of canopy PV and 100 kilowatt-hours of energy storage – plus that perpetual San Diego sunshine – and some extremely smart technology, this system should be able to meet the electricity needs of its five EV charging stations without much help from the grid, while also frequently funneling energy to the grid.

San Diego Zoo solar to EV charging

image via San Diego Gas & Electric

To give you a sense of the scale of this PV array, your average residential setup these days runs around 5 kW, so we’re talking the equivalent of 18 home systems. The PV canopies at the zoo are so extensive, in fact, that 50 cars can park under them.

Just as impressive, the system – outlined in all its complexity in very solid San Diego Daily Transcript story – is far more sophisticated than a typical grid-tied solar array, thanks to what’s called a demand response inverter.

This bit of technology from Princeton Power Systems allows the zoo PV array to directly power vehicles; charge the vehicles from energy stored in the big batteries; send power to the grid when its batteries overflow; take advantage of grid power at night or at other times when solar production (and battery storage) runs low yet  cars need to charge; and run utterly independent of the grid when it wants to or needs to – a huge advantage, as Hurricane Sandy just demonstrated.

San Diego Zoo solar to EV charging

image via San Diego Gas & Electric

The charging stations are part of the Blink Network, from Ecotality, which got a big federal grant to get the country started toward an EV infrastructure.

“The Solar-to-EV project is a cornerstone in the City of San Diego’s ongoing efforts to usher in sustainable solutions for Balboa Park in anticipation of the Park’s 2015 Centennial Celebration,” San Diego Mayor Jerry Sanders said in a statement. “This project will serve as a new energy infrastructure blueprint that can be replicated throughout the San Diego region and beyond.”

The project was done through Smart City San Diego, a collaboration between the power utility San Diego Gas & Electric, the city of San Diego, GE, UC San Diego and CleanTech San Diego. For more about the group and its activities, check out our story from this past January.

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.