Purdue students mark 25 years of building, racing solar-powered cars

WEST LAFAYETTE, Ind. — Purdue University's tradition of building solar cars for competition reached the quarter-century mark this year with another addition to the long line of vehicles.

Beginning in 1991, with a vehicle built from a van and solar panels, students have continued to refine and improve the projects turned out every two years. This year, Renatus (Latin for "rebirth") is Purdue Solar Racing's 10th vehicle.

The project is ongoing since 2015 with a changing group of students. Twenty-five members make up the solar racing team, ranging from graduate students to freshmen.

Bogdan Vlahov, president of the solar racing club, said Renatus is expected to become the fastest in the club’s line of competing solar cars by surpassing the previous top speed mark set in 2005.

"With Renatus, we can go up to 65 mph," he said. "We can't go that fast for very long, but the amount of solar cells we have on there will provide us with a good amount of power. Not enough to keep it from completely draining, but enough to keep us going for quite a while."

The main improvement of this car is the size. It is 17 feet long and 6 feet wide, just two inches off the maximum allowed size for the solar cars. The solar cells covering the slightly aerodynamically curved top of the car turn as much as 22 percent of the light that hits them into electricity.

"A lot of the other cars from Purdue Solar Racing are a lot smaller than this one," Vlahov said. "We wanted to try to fit as many solar panels as we could on this."

Renatus is being built for competition next summer in the Formula Sun Grand Prix. The winner of the three-day track race is determined by which car records the most laps.

Video of Purdue Solar Racing’s work is available at https://www.youtube.com/embed/DfwlJb7nRvs.

"We're one of the largest cars in the race, so we hope that will translate into having a longer running time on the track," Vlahov said.

Purdue Solar Racing has recorded several milestones in recent years. Teams competing in the Shell Eco-Marathon won their division for six straight years, 2008-2013.

Pulsar, the club's seventh car, achieved a record-breaking 5,000 mpg in 2009. Celeritas won the 2011 and 2012 Solar Urban Concept division in the Shell Eco-Marathon with a peak efficiency of 2,300 mpge (miles per gallon equivalent). Navitas won the Urban Concept Battery Electric division of the 2013 Shell Eco-Marathon with an efficiency of about 2,600 mpge.

Although the cars are designed and built for different races, each team learns from its predecessor. Pulsar, built in 2008, still sits in the solar racing's workshop in the Grounds Service Building along South Russell Street.

"This car was designed for a difference race, an efficiency race," Vlahov said. "What we learned from this one was about the solar cells, the layout on the car as well as what we used to laminate them and how that can affect how much power the solar cells get."

The team uses light carbon fiber for the body of the Renatus vehicle. Most of the chassis is made of carbon fiber composite and with a stainless steel roll cage. The group is split into several areas ranging from the initial car design to the current areas of work. Some members are soldering and laminating solar cells and writing code for the lighting and steering system while others are making carbon fiber for the body and working on the suspension and machining other parts.

Vlahov said the Purdue Solar Racing team is a true interdisciplinary project.

"We have a biology student on the team and some of the freshmen who are looking into joining are in pharmacy and communications," said Vlahov, a major in computer sciences and mechanical engineering.

"We do have a lot of engineers, but we can accommodate anybody. Everybody is welcome to come and learn and have fun trying to build a solar car." 

Writer: Brian L. Huchel, 765-494-2084, bhuchel@purdue.edu 

Source: Bogdan Vlahov, 765-714-6205, president@purduesolar.org

Note to Journalists: Video is available at https://www.youtube.com/embed/DfwlJb7nRvs